Boron-Doped Graphene Directly Grown on Boron-Doped Diamond for

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Boron-Doped Graphene Directly Grown on Boron-Doped Diamond for High-Voltage Aqueous Supercapacitors Dongdong Cui, Hongji Li, Mingji Li, Cuiping Li, Lirong Qian, Baozeng Zhou, and Baohe Yang ACS Appl. Energy Mater., Just Accepted Manuscript • DOI: 10.1021/acsaem.8b02120 • Publication Date (Web): 24 Jan 2019 Downloaded from http://pubs.acs.org on January 27, 2019

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ACS Applied Energy Materials

Boron-Doped Graphene Directly Grown on Boron-Doped Diamond for HighVoltage Aqueous Supercapacitors

Dongdong Cui,† Hongji Li,*,‡ Mingji Li,*,† Cuiping Li,† Lirong Qian,† Baozeng Zhou,† and Baohe Yang†

†Tianjin

Key Laboratory of Film Electronic and Communication Devices, School of Electrical

and Electronic Engineering, Tianjin University of Technology, Tianjin 300384, P. R. China ‡Tianjin

Key Laboratory of Organic Solar Cells and Photochemical Conversion, School of

Chemistry and Chemical Engineering, Tianjin University of Technology, Tianjin 300384, P. R. China KEYWORDS: high energy density, boron-doped diamond, boron-doped graphene, sodium ion, supercapacitors

ABSTRACT: Boron-doped graphene/boron-doped diamond (BG/BDD) is synthesized by an electron-assisted hot-filament chemical vapor deposition (EA-HFCVD) method. Boron atoms are effectively doped into the graphene and diamond, and BG sheets are grown vertically on the BDD. The boron content of the BG affects the BG/BDD-electrode performance, and the electrode has a high specific capacitance when the BG is grown at a B-source-gas flow rate of 50 sccm. The electrochemical behavior of the BG/BDD electrode is analyzed in both positive and negative potential windows in three-electrode configurations using saturated aqueous NaCl as the

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electrolyte; a symmetric supercapacitor (SSC) is subsequently fabricated to evaluate the practical application of the BG/BDD electrode. The BG/BDD-based device operates at a high voltage of 3.2 V. The SSC delivers a high energy density of 79.5 Wh kg-1 at a power density of 221 W kg-1, and a high power density of 18.1 kW kg-1 at an energy density of 30.7 Wh kg-1; it also retains 99.6% of its specific capacitance in the 0–2.5 V (3.2 A g-1, 9000 cycles) voltage range, and 96.1% in the 0–3 V (12.8 A g-1, 10000 cycles) range; consequently, the device has a long-term stability advantage at high operating voltages.

INTRODUCTION Exploiting the gap between the energy density of a supercapacitor (SC) and a rechargeable battery can potentially lead to the development of commercial electrochemical SCs with both high power and energy densities, which is a goal in this field.1-5 The energy density of an SC is proportional to its specific capacitance and the square of the operating voltage (E = CV2/2). Researchers have proposed the use of asymmetric supercapacitors (ASCs) as a strategy for achieving increased working voltages, and the use of pseudocapacitive active materials for achieving increased specific capacitances,6-10 while organic,11 ionic-liquid,12 lithium-ion,13-15 sodium-ion,16, 17 and other electrolyte systems18 have been examined with the aim of increasing the energy densities of SCs. Positive materials have flourished to date, while the development of negative materials has lagged.19-21 From the perspective of constructing SCs, the use of a current collector with strong mechanical properties and high conductivity as the support for the active material, and the construction of additive-free electrodes, have also been strategies for increasing the specific capacitances of SCs.22 This, of course, leads to the following question: What active materials and current collectors can be used, and what combination can be used to construct the


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most practical electrodes for SCs that ensure both wide potential windows and high specific capacitances? Doped graphenes, such as boron-doped graphene (BG),23 nitrogen-doped graphene (NG),24, 25 sulfur-doped graphene (SG),26 and phosphorus-doped graphene (PG),27 have been favored by researchers because of their large specific capacitances, high conductivities, and high electrochemically active areas that are obtained by creating bandgaps. Doped graphenes have many applications in electrochemical energy storage, including lithium-ion batteries, SCs, hydrogen production and storage, fuel cells, and solar cells.28-30 For instance, the NG can increase the capacitance of the electrodes by creating stronger interactions between Li+ and NC.31 Cheng and co-workers synthesized BG by heat treatment of graphene and used them as anode electrodes in a lithium-ion battery. The BG anode exhibited high capacity of 235 mAh g-1 at a current density of 25 A g-1.29 However, graphene derivatives are also nanomaterials, and their tendencies to readily agglomerate are similar to those of other nanomaterials; consequently, their dispersion states directly affect their electrochemical performance.32, 33 For example, while the theoretical specific capacitance of single-layer graphene is 550 F g-1, the specific capacitances of graphene-based materials derived from graphene oxide (GO) are less than half of the theoretical specific capacitance due strong van der Waals interactions between the graphene sheets that result in their restacking.34 Porous graphene materials have larger surface areas, higher electrical conductivities, and lower oxygen and hydrogen contents than their non-porous counterparts, resulting in high gravimetric capacitances and energy densities.35,

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In addition, SC devices

composed of curved graphene,37 activated graphene,38 and solvated graphene30 exhibit superior energy-density performance.


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In previous work, graphene grown vertically on a substrate was shown to exhibit high electrocatalytic activity because the three-dimensional (3D) structure formed had a high active surface area.39 Such graphene electrodes are devoid of both polymer binders and conductive additives, which clearly improves the use of the active material and the electron-transfer ability of the electrode.40,

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Graphene sheets grown directly on boron-doped diamond (BDD) film are

advantageous for the following reasons. Firstly, BDD has a large potential window, is chemically inert, is highly electrocatalytic and electrically conductive, and is very mechanically hard, which is beneficial for further increasing the power densities of BDD-electrode-based SC devices.42-44 Secondly, the graphene layer has a multi-stage porous network structure, which is directly integrated with the BDD layer through phase transitions; hence the graphene/BDD electrode is structurally strong and stable, and is not easily collapsed. Thirdly, efficient charge transport between the graphene and the BDD is achieved through the combination of sp2 and sp3 C-C bonds, and electronic devices with high current-carrying capacities have been constructed using films with graphene–diamond structures.45 In this context, herein, we report the successful construction of a BG/BDD electrode in which the BG sheets are, for the first time, grown vertically on the BDD surface. Redox-enhanced electrochemical capacitors are a class of augmented SCs that use reversible redox reactions of soluble redox couples in an electrolyte.46 The capacitance of an electric double layer and the Faraday capacitance are related to the conductivity and electrochemical activity of the electrolyte.47 We constructed a symmetrical supercapacitor (SSC) using BG/BDD electrodes and an aqueous sodium chloride (NaCl) electrolyte. The SSC device based on the abovementioned BG/BDD electrode exhibited superior performance, including high energy and power densities.


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The excellent cycling lifespan is a notable achievement of the assembled device, which highlights the potential applications of this electrode in highly efficient energy-storage systems.

RESULTS AND DISCUSSION Characterizing the BG/BDD Films. The procedure for the vertical growth of BG/BDD on a tantalum sheet is displayed schematically in Figure 1a. The BDD and BG are formed in the electron-assisted hot-filament plasma (EA-HF) CVD system through the following chemical reactions. Methane (CH4), as the main carbon source, decomposes to form hydrocarbon- and carbon-radicals (CH4 → (C, C•, CH•, CH2•, CH3•, H•) + H2).48 Ethanol (CH3CH2OH) also plays a role in the formation of BG (CH3CH2OH → 2C + H2O + 2H2). Trimethylborate (B(OCH3)3) decomposes at high temperature and reacts with the carbon atoms to form B-C bonding structures (2B(OCH3)3 →B2O3 + 6C + 6H2 + 3H2O; xB2O3 + (2+3x)C → 2BxC + 3xCO).49 An AC power supply and a DC-bias power supply are the two methods of heating used in the EA-HFCVD system. A large number of hydrocarbon radicals (CHx•) are formed around the hot filament, and these radicals form a plasma stream that bombard the substrate surface and become nucleated under the action of the low-current DC electric field. Experimentally, we successfully transformed the diamond phase into the graphene phase. The most significant differences in the growth conditions for BDD and BG are the CH4/H2 flow ratio (1/50 for BDD and 1/4–1/1 for BG), the total pressure (5067 Pa for BDD and 400 Pa for BG), bias current and voltage (10 A/200 V for BDD and 4 A/26 V for BG), and the distance between the filament and the sample stage (3 cm for BDD and 1 cm for BG). These conditional parameters are the decisive factors that reconstitute the sp3 C-C bonds on the BDD surface as sp2 C-C bonds. Theoretical studies have also confirmed that this phase-transition process is affected by the reaction conditions.50 Our detailed density


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functional theory calculations revealed that boron dopants facilitate the conversion of sp3 C-C bonds into sp2 C-C bonds. The incorporated elemental boron also accelerates the sp3 to sp2 phase conversion; graphene is grown directly on the surface of the BDD because the formation of graphene on diamond is a spontaneous process that has no energy barrier.50, 51

Figure 1. (a) Illustrating the BG/BDD-growth procedure on Ta. (b) Structural diagram of the symmetrical supercapacitor (SSC). (c) Photographic images of the electrodes, separator, CMC/NaCl electrolyte, and the BG/BDD-based SSC. The Ta and BDD layers of the BG/BDD/Ta electrode are current-collectors, with the BDD layer displaying low background current. However, the BG/BDD combination produces a BG/BDD/Ta electrode with a high current-carrying capacity, since the BG directly grown on the BDD results in an sp2-C to sp3-C phase transition.45 Consequently, we constructed an SSC device composed of


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two BG/BDD/Ta electrodes separated by a sodium chloride/ carboxymethylcellulose sodium (NaCl/CMC) gel electrolyte (Figures 1b and 1c). We examined the surfaces and cross-sections of the BDD and BG/BDD samples by scanning electron microscopy (SEM) (Figures 2 and S1), which revealed that the polycrystalline BDD is composed of high-quality crystals that are less than 5 μm in size (Figure S2). The BG sheets cover the entire surface of each crystal plane of each BDD grain. We confirmed that the BG sheets grew perpendicular to the crystal planes of the diamond by examining the BG/BDD sample with a BG growth time of 30 s, since the BG growth time mainly affects the height of the BG layer. The BG layer was 20 μm thick at a growth time of 10 min; consequently, the grain boundaries of the BDD crystals were not clearly visible in the SEM image of the surface. The phase structures of the BDD and BG/BDD were characterized using powder X-ray diffraction (XRD) analysis (Figure S3). Except for the indexed Ta (JCPDS card no.89-5158), TaC (JCPDS card no.65-0282), and Ta2C peaks (JCPDS card no.18-1296), the diffraction peaks at 44.32, 75.58, 91.7° can be assigned to the (111), (220), (311) planes of diamond (JCPDS card no.65-0537), and the other single diffraction peak at 26.26° can be assigned to the (002) planes of graphene (JCPDS card no.23-0064). Figure S4 displays the TEM image of the BG nanosheets and the corresponding selected area electron diffraction (SAED) pattern. The SAED pattern of BG nanosheets shows the diffraction rings corresponding to the (002), (100), and (110) crystal planes of graphene from inside to outside, which is caused by the irregular distribution of multilayer graphene sheets. In addition, the BG sample grown for 30 s exhibited the largest volumetric capacitance (1047.8 F cm-3) of all of the prepared samples; however, the areal specific capacitance was only 21 mF cm2.

The BG sample grown for 10 min exhibited a high areal specific capacitance of 236 mF cm-2


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despite a volumetric capacitance of only 152.8 F cm-3; the weight of the BG layer was accurately determined at this growth time. The capacitance changed only slightly for growth times longer than 10 min; consequently, the BG layer was grown for 10 min in subsequent experiments, unless otherwise stated (Figure S5).

Figure 2. SEM images of: (a and b) BDD; (c and d) BG/BDD with a BG growth time of 30 s; and (e and f) BG/BDD with a BG growth time of 10 min. Figure 3a shows a dark-field transmission electron microscopy (TEM) image and the corresponding energy-dispersive X-ray spectroscopy (EDX) elemental maps of a BG sheet grown for 10 min at a B-source-gas flow rate of 50 sccm. The C, B, and O elemental distributions suggest that boron is uniformly distributed throughout the BG sheet. The composition and valence states of the BG-layer surface species were examined by X-ray photoelectron spectroscopy (XPS) (Figure 3b). The survey XPS spectrum exhibits signals corresponding to elemental C, B, and O, in atomic percentages of 95.37, 1.81, and 2.82%, respectively. The deconvoluted C 1s spectrum of BG displays four peaks; the two main peaks at 284.8 and 285.6 eV correspond to the binding energies of sp2 C-C and C-OH bonds, respectively, while the smaller peak at 290 eV confirms the


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presence of COOH groups, and the weak peak at 283.1 eV corresponds to C atoms with one neighboring boron, indicating that highly reduced B-doped graphene was produced by CVD.52, 53 The peak at 187.1 eV in the B 1s core spectrum of BG is assigned to B that is substitutionally incorporated into the graphene and is bonded to three C atoms in the lattice, while the peak at 189.3 eV corresponds to B-C environments in the BG lattice.53 The peaks at 531.6 and 533.2 eV in the O 1s spectrum are assigned to C-O bonds and C-O-C/C-OH- derived from some Ocontaining groups on the BG surface due to CO2 and H2O in the air.27 In addition, we used C 1s and B 1s XPS to analyze the boron content in the BG produced at different B-source-gas flow rates during the growth of BG, as well as the influence of flow rate on the carbon components of the BG samples (Figure 3c). Elemental boron was detected at contents between 1.04 and 2.45 at% at B-source-gas flow rates in the 20–100 sccm range. The C 1s peak was observed to broaden and become more asymmetrical with increasing boron content, which indicates that the carbon component is abundant. At the same time, the weak B-C related peak (283.1 eV) was observed to grow.


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Figure 3. (a) TEM image and corresponding EDX elemental C, B, and O maps of BG prepared at a B-source-gas flow rate of 50 sccm. (b) XPS survey spectrum and C 1s, B 1s, and O 1s spectra of BG grown at a B-source-gas flow rate of 50 sccm. (c) C 1s and B 1s XPS spectra of BG layers grown at various B-source-gas flow rates, and the dependence of the B content in the BG layer on the B-source-gas flow rate during the growth of the BG layer. (d) Raman spectra of BG layers prepared at various B-source-gas flow rates, and an enlarged spectrum of the BG prepared at 100 sccm. The BG samples were grown for 10 min. We also investigated the dependence of the Raman spectrum of BG on boron content (Figure 3d). Three characteristic peaks are usually analyzed in the Raman spectra of vertically grown graphene derivatives, namely the D peak at 1348.9 cm-1, the G peak at 1589 cm-1, and the 2D peak at 2698.3 cm-1.32, 39, 54 The G peak originates from in-plane sp2-carbon vibrations. 55 The presence of a highly intense sharp D peak in the spectrum of the BG sample is consistent with the existence of large numbers of exposed sides and faces that are ascribable to the vertical growth of BG sheets, and the existence of multiple defects, such as B-doping, in the hexagonal carbon lattice. The increase in the intensity of the 2D peak following the formation of BG is consistent with fewer carbon layers following growth. The G peak exhibited a blue shift, from 1584 to 1589 cm-1, the 2D peak gradually decreased in intensity, and the region between the D peak and the G peak became more intense as the B-source-gas flow rate was increased from 0 to 100 sccm. Taking the BG sample prepared at a B-source-gas flow rate of 100 sccm as an example, an additional peak was observed at 1533 cm-1 following deconvolution of the region between the D and G peaks, which is formed by the splitting of the G peak due to differences in C-C vibrational energies.56 These phenomena indicate that the graphene structure is affected by the boron content.54


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Electrochemical Performance of BG/BDD Films as Positive and Negative Electrodes. The electrochemical behavior of the BG/BDD electrode was examined using a three-electrode system with saturated aqueous NaCl as the electrolyte. Nyquist plots of BDD, BG/Ta, and BG/BDD/Ta are shown in Figure 4a, with the equivalent circuit and a schematic diagram of the BG/BDD electrode also shown. The equivalent series resistance (Rs) includes the electrolyte resistance and the internal resistance of the electrode, the charge-transfer resistance (Rct) refers to the resistance at the electrode/electrolyte interface, and the interfacial resistance (R1) is related to the electrontransfer process at the BG/BDD interface. The slope of the straight line in the low-frequency region of the Nyquist plot provides the Warburg resistance (Zw), which is largely due to the diffusive resistance of the electrolyte ions into the interiors of the active materials. The rapidity of the charge-transfer process of the device at the electrolyte/electrode interface and the low diffusion resistance can clearly be determined by the small semicircle in the high-frequency region, and the straight-line segment in the low frequency region.


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Figure 4. (a) Nyquist plots for the BDD, BG, and BG/BDD electrodes in saturated aqueous NaCl. The corresponding equivalent circuit and a schematic of the structure of the BG/BDD electrode are also provided. (b) CV curves of BG prepared at various B-source-gas flow rates in different potential windows at a scan rate of 100 mV s-1. (c–e) Correlations between gravimetric and volumetric capacitances when different B-source-gas flow rates were used to grow the BG. The Nyquist plots of the BDD, BG, and BG/BDD electrodes reveal that the BG/BDD electrode is associated with the lowest Rs and Rct values (1.5 and 2.4 Ω), which indicate the BG/BDD/Ta electrode is very electrically conductive and has a high ion-current/electron-current conversion efficiency. In addition, the low-frequency region of the Nyquist plot of the BG/BDD/Ta electrode is almost linear, which reveals low Warburg resistance for fast ion diffusion. The SSC device, which consists of two electrodes, has a device capacitance that is equivalent to the sum of the two separate capacitor electrodes in series. Clearly, the BG/BDD/Ta film is an exceptional electrode that exhibits excellent electrochemical performance for SC applications. The influence of boron content on the specific capacitance of the BG was investigated using a series of BG samples prepared at various B-source-gas flow rates in the 10 to 100 sccm range. The morphology of the BG layer did not change significantly when prepared in the 10–50 sccm Bsource-gas flow-rate range; both the size of BG sheets and the volume capacities of the BG layers are small when prepared in the 60–100 sccm B-source-gas flow-rate range, as evidenced by the SEM images (Figure S6). The cyclic voltammetry (CV) curves (Figures 4b and S7) reveal that the boron content has little influence on the negative potential window; however it increases the positive potential window, which we ascribe to the redox reactions of Na+ ions on the BG layer (C + xNa+ + x e- ⇆ NaxC). In the positive potential range, the oxidation peak was observed to shift toward positive potentials, while the reduction peak shifted toward negative potentials as the B-


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source flow rate was increased from 0 to 50 sccm. This pseudo-capacitance behavior resulted in an increase in the potential window of the BG/BDD electrode. Controlling the overpotentials of hydrogen/oxygen evolution using specific electrode materials is an efficient strategy for improving the working voltage of aqueous SCs. 13 The BDD has high oxygen evolution overpotential in an aqueous solution, and a large number of hydroxyl radicals are generated on the surface of the BDD.57 The concentration of H+ and OH- ions in the neutral saturated NaCl solution is low. In addition, a faradaic reaction exists between Na+ and the BG layer. These factors change the surface charge balance of the BG/BDD electrode, thus inhibiting the oxygen evolution reaction and expanding the potential window in the aqueous solution. As the B-source flow rate is further increased from 50 to 100 sccm, the potential window becomes small, but the pseudo-capacitance behavior is maintained. However, the BG prepared at 50 sccm exhibited the maximum positivepotential specific capacitance of 174 F g-1 (198 F cm-3), and a negative-potential specific capacitance of 16 F g-1 (18 F cm-3) at a potential scan rate of 100 mV s-1. Clearly, the BG/BDD electrode fabricated with BG prepared at a B-source-gas flow rate of 50 sccm is an excellent positive active material that can also be used as a negative active material (Figure 4 c–e).


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Figure 5. Electrochemical properties of the BG/BDD electrode prepared with a B-source-gas flow rate of 50 sccm. (a) CV curves in various potential windows at 100 mV s-1. (b) Gravimetric and volumetric capacitances as functions of potential window. (c) CV curves at various scan rates. (d) The relationships between capacitance and scan rate in various potential windows. (e) Gravimetric and volumetric capacitances as functions of current density. (f) Depicting the retention of electric charge in various potential windows at a current density of 200 A g-1, as determined from the GCD curves. (g) Capacitance retention in the 0–1 V potential window at a current density of 0.1 A g-1, as determined from the GCD curves. The CV curves (Figures 5a and S8a) and galvanostatic charge-discharge (GCD) curves (Figure S8b) of the BG/BDD electrode were acquired in a variety of potential windows. The specific capacitance of the BG/BDD electrode was found to be directly related to the potential window; a


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large 0–2 V positive-potential range was achieved as a consequence of the faradaic behavior of BG in NaCl, while a negative-potential range of -1–0 V was also achieved, which highlights the electric double-layer capacitance behavior of carbon materials.58 In addition, the specific capacitance was 491.5 F g-1 (511.2 F cm-3) at a high current density of 200 A g-1 in the large -1.0– 1.9 V potential window (Figures 5b). Such high current-carrying capacity is due to the sp2-C to sp3-C phase change associated with the directly grown graphene layer on diamond.45 Figure 5c displays CV curves of the BG/BDD electrode within the 0–2 V potential ranges at scan rates in the 10–100 mV s-1 range. The CV curves exhibit pairs of redox peaks that reflect quasi-reversible redox reactions; the calculated specific capacitances are displayed in the Figure 5d, while Figure S8(c and d) shows CV curves in the -1–0 V and -1–2 V potential windows at different scan rates. The electrochemical behavior of the BG/BDD electrode is further corroborated by the GCD curves in the 0.32–160 A g-1 current-density range in different potential windows (Figures 8Se and S9); these GCD curves display distinct plateaus that are consistent with the redox peaks observed in the CV curves. Figure 5e displays the specific capacitance of the BG/BDD electrode as a function of current density. The statistical specific-capacitance values reveal that the large potential window clearly contributes to the high specific capacitance; the rate performance and specific capacitance of the electrode are higher in the positive-potential window than in the negative window. Significantly, the specific capacitance of the BG/BDD electrode was observed to be 200.6 F g-1 (203.9 F cm-3) at 0.64 A g-1 (0.65 A cm-3) in the 0–2 V potential window. The electrode still delivered a high-specific capacitance of 214.1 F g-1 (217.6 F cm-3) as the current density was increased to 16 A g-1 (16.3 A cm-3), which is about 93.7% of its initial value and is suggestive of a high rate capability.


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To investigate the current-carrying capacity of the BG/BDD electrode, we continuously acquired GCD curves for each of 300 cycles at a high current density of 200 A g-1 in different potential windows. The quantity of electric charge (Q) of the electrode was observed to sharply increase in the 2.8 V potential window; however, Q gradually declined in the 2.9 V potential window and the BG sheets also began to separate from the BDD surface (Figure 5f). We also investigated the stability of the electric-double-layer capacitance of the BG/BDD electrode in the 0–1 V potential window because no redox reactions were observed in this range (Figure 5g). The BG/BDD electrode exhibited a high reversible capacity of 2.79 mA h g-1 after 9000 cycles at 100 mA g-1. The specific capacitance and the coulombic efficiency of the BG/BDD electrode were retained at levels of approximately 104.5% and 102%, respectively, indicative of high ion-diffusion efficiency over long-term cycling. BG/BDD//BG/BDD Symmetrical Supercapacitor (SSC) Devices. In order to demonstrate that the BG/BDD electrode can feasibly be applied in practical electrochemical energy-storage-device applications, several SSC devices were fabricated using two BG/BDD electrodes and NaCl/CMC as a gel electrolyte, as shown schematically in Figure 1b. The CV and GCD curves of the SSC device were first acquired in different voltage windows (Figures 6a, 6b, S10, and S11). The shape of the CV curve was observed to change from rectangular to triangular with increasing operating voltage, which verifies that the electric double-layer capacitance and pseudo-capacitance are synergistically related. Clearly, the insertion/extraction reactions involving Na+ ions occur repeatedly in the SSC device at operating voltages in excess of 2.5 V, and a high SSC-device working voltage of 2.7 V was found to be stable. Polarization is clearly observed at working voltages that exceed 3.2 V, which is ascribable to the O-evolution reaction. The specific


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capacitance was determined to be 34.3 F g-1 at 100 m V s-1 by CV (Figure 6a,c), and 55.5 F g-1 at 12.8 A g-1 by GCD at an operating voltage of 3.2 V (Figures S10 and 6c). Figure 6d displays CV curves of the SSC device at scan rates that range from 100 to 1000 mV s-1 in the 0–3.2 V voltage window. Each CV curve exhibits a pair of redox peaks that are attributable to redox reactions associated with the insertion and extraction of Na+ ions. On the other hand, CV curves at different scan rates have similar shapes, which reveals that the device has excellent rate properties for ionic- and electronic transmission. To further verify the electrochemical performance of the SSC device, GCD curves were recorded over a variety of current densities and operating-voltage ranges (Figures 6e and S11). The GCD curves at working voltage above 2.7 V and current densities in the 1.6–16 A g-1 range are displayed in Figure. 6e. Nearly symmetric GCD curves were recorded for the SSC device at operating voltages of 2.7, 3.0, and 3.2 V, which correspond to current-density ranges of 1.6–16, 0.16–16 A g-1, and 9.6–16 A g-1, respectively. The specific capacitances of the SSC device, as determined from the GCD curves, are shown in Figure 6f. The specific capacitance of the SSC device was observed to increase with increasing operating voltage and decreasing current density. The device delivers a specific capacitance of 60.4 F g-1 at a current density of 9.6 A g-1, based on the total mass of the active materials at the high working voltage of 3.2 V, but declines to 43.1 F g-1 at a current density of 16 A g-1, suggestive of prominent rate capability.


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Figure 6. Electrochemical energy-storage performance of the BG/BDD-based SSC device with a NaCl/CMC solid electrolyte. (a) CV and (b) GCD curves in various voltage windows. (c) Specific capacitances as functions of voltage window. (d) CV curves at various scan rates. (e) GCD curves at various current densities. (f) Specific capacitances as functions of current density. Figure 7a displays Ragone plots that relate the energy density to the power density of the BG/BDD-based SSC device; indicators for other SCs reported in recent years are also displayed. Impressively, a maximum energy density of 79.5 W h kg-1 at a power density of 221 W kg-1 and working voltage of 3.2 V was delivered by the SSC device; it is worth mentioning that this energy density is very high and exceeds those of many reported SSCs and ASCs.16, 19, 20, 22, 24, 30, 41, 59 Compared with some previously reported SCs, our SSC devices also have the advantage of high power density, good stability, and high operating voltage in aqueous SCs (Table S1). In addition, a single BG/BDD-based SSC device (effective area of 1 cm2) was charged to 2.5 V for 3 s, after which it powered 37 LEDs (starting voltage of 1.8–2.2 V, 20 mA) for about 9 s, while two SSC


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devices (effective area of a single device: 20 cm2) in series, when charged to 6 V, drove a fan, a scrolling LED display, and charged a mobile phone (Figure 7b).

Figure 7. (a) Ragone plots for the BG/BDD-based SSC device and other reported graphene-based SCs. (b) CV curves of a single BG/BDD-based SSC device (20 cm2) (red) and two SSCs (blue) in series overlaid on photographic images that show four applications of the BG/BDD-based SSC devices: An SSC device (effective area of 1 cm2) can light up 37 parallel-connected LEDs (starting voltage of 1.8–2.2 V, 20 mA); two 20 cm2 SSCs in series can drive a 1.24 W electric fan (2V, 620 mA), a 0.1 W scroll display (3.8 V, 26 mA), and can also charge a cell phone (5 V, 275 mA). We investigated the long-term stability of the BG/BDD-based SSC under a variety of conditions (Figure 8). The CV traces displayed in Figure 8a were recorded at a high scan rate of 1000 mV s1;

the SSC retained 106.1% of its initial specific capacitance after 1000 testing cycles. The lowest

retention of capacitance (93.7%) was observed after 2520 cycles when operated at 2.5 V and a current density of 3.2 A g-1; however, this rose to 99.6% after 9000 cycles (Figure 8b). At an operating voltage of 3 V and a current density of 12.8 A g-1, the capacitance retention dropped to 84.7% at the 5900th cycle, but then increased to 96.1% after 10000 cycles (Figure 8c).


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Figure 8. Cycling stability of the BG/BDD-based SSC device in terms of capacitance retention, obtained from a) CV curves (inset) at scan rate of 1000 mV s-1, b) GCD curves (inset) in the 0–2.5 V voltage window at a current density of 3.2 A g-1, c) GCD curves (lower inset) in the 0–3 V voltage window at a current density of 12.8 A g-1. The right inset displays Nyquist plots before and after 15000 cycles of the SSC device. Generally, the long-term cycling stability of an SC exhibits either a constant or decreasing specific-capacitance trend during continuous charging and discharging. However, the BG/BDDbased SSC exhibited both increasing and decreasing specific-capacitance trends. Ramadoss et al.41 rationalized a similar phenomenon in the following way: part of the 3D-graphene material is electrically activated, resulting in the detachment of a thin graphene sheet that, in turn, increases the surface area of the active material. Furthermore, the Nyquist plots of the SSC device before


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and after 15000 charge/discharge cycles are shown in the inset of Figure 8c; the plot after 15000 cycles exhibits a slight increase in Rct compared to the Nyquist plot prior to testing, which indicates a loss of conductivity and the deterioration of the active material due to the insertion/extraction of Na+ ions. However, after a long term cycling test, the BG layer was still intact on BDD without peeling away from the BDD, and the BG nanosheets maintained their original morphology, as shown in the SEM images (Figure S12). The SSC device still retains its large capacitance, and such structural stability indicates that this device can be developed into practical energy-storage devices. The advantage of the BG/BDD-based SSC device is clearly related to the combination of its large operating voltage, high energy density, high power density, and cycling stability. The capacitive behavior of the SSC device is rationalized as follows. The doping of graphene with boron creates a bandgap that exhibits tunable conductivity, while enriching the electrochemically active sites.60 The BDD layer in the BG/BDD electrode increases both the potential window and the mechanical/chemical stability of the electrode. BG sheets are directly deposited on the highly conductive BDD by CVD, which ensures their intimate contact and substantially reduces internal resistance, since the BG/BDD electrode is devoid of dead volume (polymer binders and conducting agents are not used). In the aqueous NaCl electrolyte, Na+ ions are repeatedly intercalated/deintercalated into/from the BG layer during the charge/discharge cycling of the SSC device through the following redox reaction: C + xNa+ + x e- ⇆ NaxC. Since this redox reaction occurs on the active surfaces of the electrodes rather than being limited by solid-state diffusion, the high power density of the SC is maintained, which is an advantage of the aqueous NaCl electrolyte.46 The BG sheets are vertically anchored on the BDD layer, which retains the open space between adjacent BG sheets, while the BG sheets can entangle to form an active-material network with a high


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specific area that expedites the migration of available ions towards contact with the active material, which maximizes the use of the active material. Furthermore, vertical BG sheets on the BDD layer effectively avoid any swelling and shrinkage of the BG-layer volume resulting from electrolyte ion-intercalation/de-intercalation during repeated charging/discharging processes. Consequently, synergism between the high-current/peak-voltage of the redox reactions involving the Na+ ions on the BG layer, and the large potential window of the BDD, increases the energy and power densities of the BG/BDD-based SSC device. CONCLUSION A previous unreported technology for the direct vertical deposition of boron-doped graphene (BG) on a BDD surface has been developed, and was used to produce high-performance BG/BDD electrodes for supercapacitors. Synergy between the BG and BDD layers results in a BG/BDD/Ta electrode that exhibits high specific capacitance, high voltage, and high rate performance. More importantly, a supercapacitor fabricated with BG/BDD negative and positive electrodes, and NaCl/CMC as a gel electrolyte, exhibited remarkable electrochemical performance in terms of high energy density (79.5 W h kg-1 at 221 W kg-1), high power density (18 kW kg-1 at an energy density of 30.7 W h kg-1), and long-term cycling stability. This study offers a useful and easily implemented strategy for the design of high-performance BDD-based composite electrodes for supercapacitors, and confirms that BG/BDD-based devices have significant potential for energystorage applications, due to their high energy densities and high power densities. At the same time, this study provides a new method for the construction of highly stable aqueous sodium-ion supercapacitors. EXPERIMENTAL SECTION


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Preparation of BG/BDD Grown on Ta. An electron-assisted hot-filament chemical vapor deposition (EA-HFCVD) system was used to deposit the BDD film on the Ta substrate, and BG was continuously deposited on the BDD surface to produce the BG/BDD electrodes. B(OCH3)3 was used as the boron (B) source, and a 3:1 (v/v) mixture of B(OCH3)3/CH3CH2OH, was carried by H2 (referred to as the “B-source gas”) and introduced into the CVD chamber. Flow rates of 6, 300, and 6 sccm were used for CH4, H2, and the B-source gas, respectively, during the deposition of the BDD film. The alternating voltage and current applied between the ends of the filaments were 9.5 V and 115 A. In addition, a DC bias voltage and current of 200 V and 10 A were applied between the hot filament and the Ta substrate. The distance from the Ta to the hot filament was approximately 3 cm. The chamber pressure, growth temperature, and growth time were 5 kPa, 950 °C, and 6 h, respectively. After the BDD layer had been prepared, the bias power supply was turned off, all gas supplies were terminated, and the system was subjected to a vacuum of 10 Pa or less. The CH4, H2, and B-source gases were re-introduced into the CVD chamber at flow rates of 10, 40, and 50 sccm, respectively, resulting in a chamber pressure of 400 Pa. The sample was subsequently raised such that it was 1 cm from the hot filament. A constant hot-filament voltage and current were used. The bias voltage, bias current, growth temperature, and growth time were 26 V, 4 A, 950 °C, and 10 min, respectively; these settings were used to prepare the BG/BDD electrode referred to herein. It should be emphasized that a B-source-gas flow rate of 50 sccm, and a growth time of 10 min was used to prepare the optimum material. The average mass loading of the BG layer of the BG/BDD electrode (with a BG growth time of 10 min) was 1.25 mg cm-2. A series of BG/BDD electrodes was prepared in a similar manner, with B-source-gas flow rates of 0–100 sccm and growth times of 0.5–20 min.


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Characterization. The morphologies, compositions, and structures of the samples were characterized. The morphologies and microstructures of the samples were examined by SEM (MERLIN Compact, Carl Zeiss, Germany) and TEM (Talos F200X, FEI, USA). The compositions and structures of the various samples were investigated by XPS (Thermo Scientific Escalab 250Xi, Thermo Fisher Scientific, USA), XRD (D/max-2500/PC, Rigaku, Japan), and Raman spectroscopy (LabRAM HR Evolution, HORIBA Scientific, Japan; YAG-laser wavelength = 532 nm). Electrochemical experiments involving individual working electrodes were performed in threeelectrode cells with Pt-foil counter electrodes and Ag/AgCl reference electrodes. Saturated aqueous NaCl was used as the electrolyte. The symmetric supercapacitor (SSC) device was constructed using two BG/BDD electrodes separated by an MPF30AC-100 membrane (areal density of 30 g m-2 and thickness of 100 m), with CMC/NaCl as the gel electrolyte. CV, GCD experiments, and electrochemical impedance spectroscopy (EIS) were carried out using a CHI 760E electrochemical workstation (Chenhua, Shanghai, China). The specific capacitance was calculated from the GCD results using the equation

C m ( or

Vol )



C m ( or

Vol )



it and m(or Vol )(V2  V1  iR )

 idV

2vm(or Vol )(V2  V1 )

from

the

. The energy ( E m ( or

SSC device were calculated using: Em ( or

Vol )



CV

Vol )

results

using

) and powder ( Pm ( or

1 C m ( or 2  3.6

Vol )

Vol )

the

equation

) densities of the

(V2  V1 ) 2 and Pm ( or

Vol )



E m ( or t

Vol )

.

In these formulas, i, △t, ν, V, iR, m, and Vol represent the discharge current (A), time (s), scan rate (V s-1), voltage (V), the voltage drop, the mass of the active material (g), and the volume of the active material (cm3), respectively. ASSOCIATED CONTENT


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Supporting Information This material is available free of charge via the Internet at http://pubs.acs.org. SEM images, Raman spectra, and, electrochemical data. AUTHOR INFORMATION Corresponding Authors *E-mail: [email protected] (H. L.) *E-mail: [email protected] (M. L.) ACKNOWLEDGEMENTS This work was supported by the National key R&D program of China (No. 2016YFB0402700), the Natural Science Foundation of Tianjin City (Nos. 17JCZDJC32600 and 16JCYBJC16300), and the Youth Top-Notch Talents Program of Tianjin City (No. TJTZJH-QNBJRC-1-13).

REFERENCES (1)

Beguin, F.; Presser, V.; Balducci, A.; Frackowiak, E., Carbons and Electrolytes for

Advanced Supercapacitors. Adv. Mater. 2014, 26 (14), 2219-2251. (2)

Zuo, W. H.; Li, R. Z.; Zhou, C.; Li, Y. Y.; Xia, J. L.; Liu, J. P., Battery-Supercapacitor

Hybrid Devices: Recent Progress and Future Prospects. Adv. Sci. 2017, 4 (7), 1600539. (3)

Brezesinski, T.; Wang, J.; Tolbert, S. H.; Dunn, B., Ordered Mesoporous alpha-MoO3

with Iso-Oriented Nanocrystalline Walls for Thin-Film Pseudocapacitors. Nat. Mater. 2010, 9 (2), 146-151. (4)

Sevilla, M.; Mokaya, R., Energy Storage Applications of Activated Carbons:

Supercapacitors and Hydrogen Storage. Energy Environ. Sci. 2014, 7 (4), 1250-1280.


25


(5)

Page 26 of 34

Yan, Y.; Luo, Y.; Ma, J.; Li, B.; Xue, H.; Pang, H., Facile Synthesis of Vanadium

Metal-Organic Frameworks for High-Performance Supercapacitors. Small 2018, 14 (33), 1801815. (6)

Zhao, J.; Li, Z. J.; Yuan, X. C.; Yang, Z.; Zhang, M.; Meng, A.; Li, Q. D., A High-

Energy Density Asymmetric Supercapacitor Based on Fe2O3 Nanoneedle Arrays and NiCo2O4/Ni(OH)2 Hybrid Nanosheet Arrays Grown on SiC Nanowire Networks as FreeStanding Advanced Electrodes. Adv. Energy Mater. 2018, 8 (12), 1702787. (7)

Jabeen, N.; Hussain, A.; Xia, Q.; Sun, S.; Zhu, J.; Xia, H., High-Performance 2.6 V

Aqueous Asymmetric Supercapacitors based on In Situ Formed Na0.5MnO2 Nanosheet Assembled Nanowall Arrays. Adv. Mater. 2017, 29 (32), 1700804. (8)

Owusu, K. A.; Qu, L.; Li, J.; Wang, Z.; Zhao, K.; Yang, C.; Hercule, K. M.; Lin, C.;

Shi, C.; Wei, Q.; Zhou, L.; Mai, L., Low-Crystalline Iron Oxide Hydroxide Nanoparticle Anode for High-Performance Supercapacitors. Nat. Commun. 2017, 8, 14264. (9)

Yan, Y.; Gu, P.; Zheng, S.; Zheng, M.; Pang, H.; Xue, H., Facile Synthesis of An

Accordion-Like Ni-MOF Superstructure for High-Performance Flexible Supercapacitors. J. Mater. Chem. A 2016, 4 (48), 19078-19085. (10)

Li, Y.; Xu, Y.; Yang, W.; Shen, W.; Xue, H.; Pang, H., MOF-Derived Metal Oxide

Composites for Advanced Electrochemical Energy Storage. Small 2018, 14 (25), 1704435. (11)

Ajuria, J.; Redondo, E.; Arnaiz, M.; Mysyk, R.; Rojo, T.; Goikolea, E., Lithium and

Sodium Ion Capacitors with High Energy and Power Densities Based on Carbons From Recycled Olive Pits. J. Power Sources 2017, 359, 17-26. (12)

Mousavi, M. P. S.; Wilson, B. E.; Kashefolgheta, S.; Anderson, E. L.; He, S.;

Bühlmann, P.; Stein, A., Ionic Liquids as Electrolytes for Electrochemical Double-Layer


26

Page 27 of 34 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Capacitors: Structures that Optimize Specific Energy. ACS Appl. Mater. Interfaces 2016, 8 (5), 3396-3406. (13)

Zuo, W.; Xie, C.; Xu, P.; Li, Y.; Liu, J., A Novel Phase-Transformation Activation

Process toward Ni-Mn-O Nanoprism Arrays for 2.4 V Ultrahigh-Voltage Aqueous Supercapacitors. Adv. Mater. 2017, 29 (36), 1703463. (14)

Yu, M. H.; Lin, D.; Feng, H. B.; Zeng, Y. X.; Tong, Y. X.; Lu, X. H., Boosting the

Energy Density of Carbon-Based Aqueous Supercapacitors by Optimizing the Surface Charge. Angew. Chem.-Int. Ed. 2017, 56 (20), 5454-5459. (15)

Zhao, L.; Li, H.; Li, M.; Xu, S.; Li, C.; Qu, C.; Zhang, L.; Yang, B., Lithium-Ion

Storage Capacitors Achieved by CVD Graphene/TaC/Ta-Wires and Carbon Hollow Spheres. Appl. Energy 2016, 162, 197-206. (16)

Le, Z. Y.; Liu, F.; Nie, P.; Li, X. R.; Liu, X. Y.; Bian, Z. F.; Chen, G.; Wu, H. B.; Lu,

Y. F., Pseudocapacitive Sodium Storage in Mesoporous Single-Crystal-like TiO2-Graphene Nanocomposite Enables High-Performance Sodium-Ion Capacitors. Acs Nano 2017, 11 (3), 2952-2960. (17)

Kurra, N.; Alhabeb, M.; Maleski, K.; Wang, C.-H.; Alshareef, H. N.; Gogotsi, Y.,

Bistacked Titanium Carbide (MXene) Anodes for Hybrid Sodium-Ion Capacitors. ACS Energy Lett. 2018, 3, 2094-2100. (18)

Jayaramulu, K.; Dubal, D. P.; Nagar, B.; Ranc, V.; Tomanec, O.; Petr, M.; Datta, K.

K. R.; Zboril, R.; Gomez-Romero, P.; Fischer, R. A., Ultrathin Hierarchical Porous Carbon Nanosheets for High-Performance Supercapacitors and Redox Electrolyte Energy Storage. Adv. Mater. 2018, 30 (15), 1705789.


27


(19)

Page 28 of 34

Lim, E.; Jo, C.; Kim, M. S.; Kim, M. H.; Chun, J.; Kim, H.; Park, J.; Roh, K. C.;

Kang, K.; Yoon, S.; Lee, J., High-Performance Sodium-Ion Hybrid Supercapacitor Based on Nb2O5@Carbon Core-Shell Nanoparticles and Reduced Graphene Oxide Nanocomposites. Adv. Funct. Mater. 2016, 26 (21), 3711-3719. (20)

Guan, B. Y.; Yu, Y.; Wang, X.; Song, S. Y.; Lou, X. W., Formation of Onion-Like

NiCo2S4 Particles via Sequential Ion-Exchange for Hybrid Supercapacitors. Adv. Mater. 2017, 29 (6), 1605051. (21)

Yan, Y.; Li, B.; Guo, W.; Pang, H.; Xue, H., Vanadium Based Materials as Electrode

Materials for High Performance Supercapacitors. J. Power Sources 2016, 329, 148-169. (22)

Patil, S. J.; Kim, J. H.; Lee, D. W., Graphene-Nanosheet Wrapped Cobalt Sulphide as a

Binder Free Hybrid Electrode for Asymmetric Solid-State Supercapacitor. J. Power Sources 2017, 342, 652-665. (23)

Han, J.; Zhang, L. L.; Lee, S.; Oh, J.; Lee, K. S.; Potts, J. R.; Ji, J. Y.; Zhao, X.;

Ruoff, R. S.; Park, S., Generation of B-Doped Graphene Nanoplatelets Using a Solution Process and Their Supercapacitor Applications. Acs Nano 2013, 7 (1), 19-26. (24)

Wu, Z.-S.; Winter, A.; Chen, L.; Sun, Y.; Turchanin, A.; Feng, X.; Müllen, K., Three-

Dimensional Nitrogen and Boron Co-doped Graphene for High-Performance All-Solid-State Supercapacitors. Adv. Mater. 2012, 24 (37), 5130-5135. (25)

Pendashteh, A.; Palma, J.; Anderson, M.; Marcilla, R., NiCoMnO4 Nanoparticles on N-

Doped Graphene: Highly Efficient Bifunctional Electrocatalyst for Oxygen Reduction/Evolution Reactions. Appl. Catal. B 2017, 201, 241-252.


28

Page 29 of 34 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(26)

Paraknowitsch, J. P.; Thomas, A., Doping Carbons Beyond Nitrogen: An Overview of

Advanced Heteroatom Doped Carbons with Boron, Sulphur and Phosphorus for Energy Applications. Energy Environ. Sci. 2013, 6 (10), 2839-2855. (27)

Wen, Y.; Wang, B.; Huang, C.; Wang, L.; Hulicova-Jurcakova, D., Synthesis of

Phosphorus-Doped Graphene and its Wide Potential Window in Aqueous Supercapacitors. Chem. - Eur. J. 2015, 21 (1), 80-85. (28)

Pullamsetty, A.; Subbiah, M.; Sundara, R., Platinum on Boron Doped Graphene as

Cathode Electrocatalyst for Proton Exchange Membrane Fuel Cells. Int. J. Hydrogen Energy 2015, 40 (32), 10251-10261. (29)

Wu, Z. S.; Ren, W. C.; Xu, L.; Li, F.; Cheng, H. M., Doped Graphene Sheets As Anode

Materials with Superhigh Rate and Large Capacity for Lithium Ion Batteries. Acs Nano 2011, 5 (7), 5463-5471. (30)

Pan, Z.; Zhi, H.; Qiu, Y.; Yang, J.; Xing, L.; Zhang, Q.; Ding, X.; Wang, X.; Xu, G.;

Yuan, H.; Chen, M.; Li, W.; Yao, Y.; Motta, N.; Liu, M.; Zhang, Y., Achieving CommercialLevel Mass Loading in Ternary-Doped Holey Graphene Hydrogel Electrodes for Ultrahigh Energy Density Supercapacitors. Nano Energy 2018, 46, 266-276. (31)

Li, X.; Zheng, S.; Jin, L.; Li, Y.; Geng, P.; Xue, H.; Pang, H.; Xu, Q., Metal-Organic

Framework-Derived Carbons for Battery Applications. Adv. Energy Mater. 2018, 8 (23), 1800716. (32)

Sasikala, S. P.; Poulin, P.; Aymonier, C., Advances in Subcritical Hydro-/Solvothermal

Processing of Graphene Materials. Adv. Mater. 2017, 29 (22), 1605473. (33)

Stoller, M. D.; Park, S. J.; Zhu, Y. W.; An, J. H.; Ruoff, R. S., Graphene-Based

Ultracapacitors. Nano Lett. 2008, 8 (10), 3498-3502.


29


(34)

Page 30 of 34

El-Kady, M. F.; Strong, V.; Dubin, S.; Kaner, R. B., Laser Scribing of High-

Performance and Flexible Graphene-Based Electrochemical Capacitors. Science 2012, 335 (6074), 1326-1330. (35)

Strauss, V.; Marsh, K.; Kowal, M. D.; El-Kady, M.; Kaner, R. B., A Simple Route to

Porous Graphene from Carbon Nanodots for Supercapacitor Applications. Adv. Mater. 2018, 30 (8), 1704449. (36)

Wang, Q.; Yan, J.; Fan, Z. J., Carbon Materials for High Volumetric Performance

Supercapacitors: Design, Progress, Challenges and Opportunities. Energy Environ. Sci. 2016, 9 (3), 729-762. (37)

Liu, C. G.; Yu, Z. N.; Neff, D.; Zhamu, A.; Jang, B. Z., Graphene-Based

Supercapacitor with an Ultrahigh Energy Density. Nano Lett. 2010, 10 (12), 4863-4868. (38)

Zhu, Y. W.; Murali, S.; Stoller, M. D.; Ganesh, K. J.; Cai, W. W.; Ferreira, P. J.;

Pirkle, A.; Wallace, R. M.; Cychosz, K. A.; Thommes, M.; Su, D.; Stach, E. A.; Ruoff, R. S., Carbon-Based Supercapacitors Produced by Activation of Graphene. Science 2011, 332 (6037), 1537-1541. (39)

Ge, C.; Li, H.; Li, M.; Li, C.; Wu, X.; Yang, B., Synthesis of A ZnO Nanorod/CVD

Graphene Composite for Simultaneous Sensing of Dihydroxybenzene Isomers. Carbon 2015, 95, 1-9. (40)

Sekhar, S. C.; Nagaraju, G.; Yu, J. S., Conductive Silver Nanowires-Fenced Carbon

Cloth Fibers-Supported Layered Double Hydroxide Nanosheets as a Flexible and Binder-Free Electrode for High-Performance Asymmetric Supercapacitors. Nano Energy 2017, 36, 58-67.


30

Page 31 of 34 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(41)

Ramadoss, A.; Yoon, K.-Y.; Kwak, M.-J.; Kim, S.-I.; Ryu, S.-T.; Jang, J.-H., Fully

Flexible, Lightweight, High Performance All-Solid-State Supercapacitor Based on 3Dimensional-Graphene/Graphite-Paper. J. Power Sources 2017, 337, 159-165. (42)

Gao, F.; Nebel, C. E., Diamond-Based Supercapacitors: Realization and Properties. ACS

Appl. Mater. Interfaces 2016, 8 (42), 28244-28254. (43)

Hébert, C.; Mazellier, J. P.; Scorsone, E.; Mermoux, M.; Bergonzo, P., Boosting the

Electrochemical Properties of Diamond Electrodes Using Carbon Nanotube Scaffolds. Carbon 2014, 71, 27-33. (44)

Hébert, C.; Scorsone, E.; Mermoux, M.; Bergonzo, P., Porous Diamond with High

Electrochemical Performance. Carbon 2015, 90, 102-109. (45)

Yu, J.; Liu, G.; Sumant, A. V.; Goyal, V.; Balandin, A. A., Graphene-on-Diamond

Devices with Increased Current-Carrying Capacity: Carbon sp2-on-sp3 Technology. Nano Lett. 2012, 12 (3), 1603-1608. (46)

Evanko, B.; Boettcher, S. W.; Yoo, S. J.; Stucky, G. D., Redox-Enhanced

Electrochemical Capacitors: Status, Opportunity, and Best Practices for Performance Evaluation. ACS Energy Lett. 2017, 2 (11), 2581-2590. (47)

Gonzalez, A.; Goikolea, E.; Barrena, J. A.; Mysyk, R., Review on Supercapacitors:

Technologies and Materials. Renewable Sustainable Energy Rev. 2016, 58, 1189-1206. (48)

Brenner, D. W., Empirical Potential for Hydrocarbons for Use in Simulating the

Chemical Vapor Deposition of Diamond Films. Phys. Rev. B 1990, 42 (15), 9458-9471. (49)

Sheng, Z.-H.; Gao, H.-L.; Bao, W.-J.; Wang, F.-B.; Xia, X.-H., Synthesis of Boron

Doped Graphene for Oxygen Reduction Reaction in Fuel Cells. J. Mater. Chem. 2012, 22 (2), 390-395.


31


(50)

Page 32 of 34

Gu, C.; Li, W.; Xu, J.; Xu, S.; Lu, C.; Xu, L.; Li, J.; Zhang, S., Graphene Grown out

of Diamond. Appl. Phys. Lett. 2016, 109 (16), 162105. (51)

Lu, C.; Yang, H.; Xu, J.; Xu, L.; Chshiev, M.; Zhang, S.; Gu, C., Spontaneous

Formation of Graphene on Diamond (111) Driven by B-Doping Induced Surface Reconstruction. Carbon 2017, 115, 388-393. (52)

Choi, S. H.; Ko, Y. N.; Lee, J.-K.; Kang, Y. C., 3D MoS2–Graphene Microspheres

Consisting of Multiple Nanospheres with Superior Sodium Ion Storage Properties. Adv. Funct. Mater. 2015, 25 (12), 1780-1788. (53)

Vineesh, T. V.; Kumar, M. P.; Takahashi, C.; Kalita, G.; Alwarappan, S.; Pattanayak,

D. K.; Narayanan, T. N., Bifunctional Electrocatalytic Activity of Boron-Doped Graphene Derived from Boron Carbide. Adv. Energy Mater. 2015, 5 (17), 1500658. (54)

Tennyson, W. D.; Tian, M.; Papandrew, A. B.; Rouleau, C. M.; Puretzky, A. A.;

Sneed, B. T.; More, K. L.; Veith, G. M.; Duscher, G.; Zawodzinski, T. A.; Geohegan, D. B., Bottom up Synthesis of Boron-Doped Graphene for Stable Intermediate Temperature Fuel Cell Electrodes. Carbon 2017, 123, 605-615. (55)

Share, K.; Cohn, A. P.; Carter, R.; Rogers, B.; Pint, C. L., Role of Nitrogen-Doped

Graphene for Improved High-Capacity Potassium Ion Battery Anodes. Acs Nano 2016, 10 (10), 9738-9744. (56)

Salvatierra, R. V.; Zakhidov, D.; Sha, J.; Kim, N. D.; Lee, S.-K.; Raji, A.-R. O.;

Zhao, N.; Tour, J. M., Graphene Carbon Nanotube Carpets Grown Using Binary Catalysts for High-Performance Lithium-Ion Capacitors. Acs Nano 2017, 11 (3), 2724-2733. (57)

Thostenson, J. O.; Ngaboyamahina, E.; Sellgren, K. L.; Hawkins, B. T.; Piascik, J. R.;

Klem, E. J. D.; Parker, C. B.; Deshusses, M. A.; Stoner, B. R.; Glass, J. T., Enhanced H2O2


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Production at Reductive Potentials from Oxidized Boron-Doped Ultrananocrystalline Diamond Electrodes. ACS Appl. Mater. Interfaces 2017, 9 (19), 16610-16619. (58)

Rantho, M. N.; Madito, M. J.; Manyala, N., Symmetric Supercapacitor with

Supercapattery Behavior Based on Carbonized Iron Cations Adsorbed onto Polyaniline. Electrochim. Acta 2018, 262, 82-96. (59)

Pendashteh, A.; Moosavifard, S. E.; Rahmanifar, M. S.; Wang, Y.; El-Kady, M. F.;

Kaner, R. B.; Mousavi, M. F., Highly Ordered Mesoporous CuCo2O4 Nanowires, a Promising Solution for High-Performance Supercapacitors. Chem. Mater. 2015, 27 (11), 3919-3926. (60)

Cattelan, M.; Agnoli, S.; Favaro, M.; Garoli, D.; Romanato, F.; Meneghetti, M.;

Barinov, A.; Dudin, P.; Granozzi, G., Microscopic View on a Chemical Vapor Deposition Route to Boron-Doped Graphene Nanostructures. Chem. Mater. 2013, 25 (9), 1490-1495.


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A chemical vapor deposition technique for preparing vertical boron-doped-graphene/boron-doped-diamond (BG/BDD) electrodes is reported. A symmetric supercapacitor composed of BG/BDD electrodes and an aqueous NaCl electrolyte operates at a high voltage of 3.2 V, a high energy of 79.5 Wh kg-1, and with a capacity retention of 96.1% over 10000 cycles, which are ascribable to the advantages provided by the BG/BDD electrodes that include high electrical conductivities and large active areas. 83x76mm (96 x 96 DPI)


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Boron-Doped Graphene Directly Grown on Boron-Doped Diamond for

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