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Three-Dimensional Structures of MoS2@Ni Core/Shell Nanosheets Array toward Synergetic Electrocatalytic Water Splitting Zhicai Xing, Xiurong Yang, Abdullah M. Asiri, and Xuping Sun ACS Appl. Mater. Interfaces, Just Accepted Manuscript • Publication Date (Web): 23 May 2016 Downloaded from http://pubs.acs.org on May 23, 2016

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ACS Applied Materials & Interfaces

Three-Dimensional

Structures

of

MoS2@Ni

Core/Shell Nanosheets Array toward Synergetic Electrocatalytic Water Splitting Zhicai Xing,†,* Xiurong Yang,† Abdullah M. Asiri,‡ and Xuping Sun†,║, § †

State Key Lab of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry,

Chinese Academy of Sciences, Changchun 130022, Jilin, China ‡

Chemistry Department & Center of Excellence for Advanced Materials Research, King

Abdulaziz University, Jeddah 21589, Saudi Arabia ║

College of Chemistry and §Analytical & Testing Center, Sichuan University, Chengdu 610064,

Sichuan, China KEYWORDS: MoS2, Nickel, Core/shell nanosheets array, Synergistic effect, Hydrogen evolution reaction ABSTRACT: Hydrogen evolution reaction (HER) in alkaline media using non-noble metal catalysts with great efficiency represents a critical challenge in current water-alkaline and chloralkali electrolyzers. Herein, we demonstrate the MoS2@Ni core/shell nanosheets array vertically aligned on carbon cloth (MoS2@Ni/CC) is a highly active electrocatalyst for HER. In alkaline solutions, MoS2@Ni/CC needs overpotentials of 91, 118, and 196 mV to approach current densities of 10, 20, and 100 mA cm-2, respectively, exceeding behavior of commercial Pt/C catalyst at high current densities. Additionally, this catalyst also exhibits excellent

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electrocatalytic activity towards HER in neutral electrolytes. Such high hydrogen evolution activities are due to synergistic electrocatalytic effects between MoS2 core and Ni shell. INTRODUCTION Hydrogen, one of clean and renewable energy resources, has been claimed to be an alternative for replacing traditional fossil fuel.1,2 An efficient and easy way for generating high-purity hydrogen is electrochemical water splitting, however, demanding researchers to find a way to implement more energy-efficient processes by developing hydrogen evolution reaction (HER) electrocatalysts.3 Pt and its alloys are widely investigated as the most efficient HER catalysts, but the operation of large-scale electrolysis systems is prohibited owing to their high cost and scarcity.3,4 Therefore, searching alternative earth-abundant materials toward simultaneously lowering the cost and improving their catalytic activities remain a crucial task.5 MoS2 has recently demonstrated its promise as an attractive non-noble metal HER catalyst with high catalytic efficiency based on both theoretical6 and experimental7 studies. Much efforts have been taken to synthesize MoS2-based HER catalysts, including various crystalline MoS2 nanostructures,7-11 amorphous MoS2,12 MoS2-based hybrid materials13-15 and molecular mimics,16 which demonstrate outstanding catalytic performance under acidic solutions but perform relatively poor activity in alkaline medias. The most commonly used catalysts for application in industrial alkaline electrolyzers are Raney Ni and its alloys17 and recent studies further suggest that Ni doped MoS2 microspheres exhibit superior HER activity over undoped MoS2 in acidic solutions.18 Recently, MoS2 nanosheets array on 3D graphene/Ni networks (MoS2/graphene/Ni) was reported to be active for HER under alkaline conditions.19 Despite such great success, it is still a big challenge to develop MoS2-based HER catalysts with remarkable catalytic activity and stability in alkaline medias.


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Microbial electrolysis cell requires HER catalysts to generate hydrogen during wastewater treatment process by microbes under neutral conditions.20-22 As such, developing efficient and inexpensive HER catalysts which function well in both alkaline and neutral electrolytes are extremely desirable but challenging. Herein, we report that electrodeposition of Ni on MoS2 nanosheets array, which are hydrothermally grown on carbon cloth (MoS2/CC), leads to MoS2@Ni core/shell nanosheets array (MoS2@Ni/CC). The unique MoS2@Ni/CC was directly used as binder-free electrode for HER in alkaline media showing a low onset overpotential of 30 mV with current densities of 10, 20, and 100 mA cm-2 at overpotentials of 91, 118, and 196 mV, respectively, with excellent stability over 50 h. It is also excellent in catalytic activity and durability under neutral conditions. The synergistic electrocatalytic effects of MoS2 core and Ni shell are likely to be responsible for the high HER activities.

EXPERIMENTAL SECTION Materials. CC was purchased from Hongshan District, Wuhan Instrument Surgical Instruments Business, China. Na2MoO4·2H2O, thiourea, NiSO4·7H2O, NaH2PO4, KOH, and Na2HPO4 were purchased from Beijing Chemical Corp., China. Pt/C (Pt on Vulcan XC-72R, 20 wt%) and Nafion (5 wt%) were bought from Sigma-Aldrich. Preparation of MoS2@Ni/CC. In a typical synthesis, MoS2/CC (MoS2 loading: 4.0 mg cm-2.) was synthesized according to previous reports.23,24 The electrodeposition of Ni on MoS2/CC was carried out in a three-electrode cell (MoS2/CC: working electrode, a graphite plate: counter electrode, and Ag/AgCl: reference electrode). The electrodeposition was performed by cyclic voltammetry over the potential window of -0.2 to -1.4 V (cycles: 20, scan rate: 50 mV s-1) in 0.1 M NiSO4·7H2O aqueous solution. All these procedures were carried out at 25 °C under nitrogen protection. After deposition, MoS2@Ni/CC was removed, rinsed, and dried by nitrogen flow


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(MoS2@Ni loading: 7.8 mg cm-2). The reference sample, Ni/CC was prepared through the similar method to MoS2@Ni/CC using the CC as the working electrode. Characterizations. Powder X-ray diffraction (XRD) patterns were used to analyze the crystal structure and phase composition of samples (RigakuD/MAX 2550 diffractometer with Cu Kα radiation, λ=1.5418 Å) with the detected diffraction angle ranging from 10 to 70° with 3 degree min-1. The morphology of these samples was characterized by scanning electron microscopy (SEM, XL30 ESEM FEG, 20 kV) and transmission electron microscopy (TEM, HITACHI H8100, 200 kV). The chemical binding energy of samples was examined using X-ray photoelectron spectroscopy (XPS, Thermal ESCALAB 250, UK). Electrochemical Measurements. All electrochemical measurements were performed according to our previous methods using a CHI660E potentiostat (CH Instruments, China).25,26 Freshly made MoS2@Ni/CC was directly used as the working electrode. The prepared Pt/C ink was dropped onto CC (Pt/C loading: 7.8 mg cm-2) for getting Pt/C loaded electrode. RESULTS AND DISCUSSION The XRD pattern given in Figure S1a exhibits four diffraction peaks of the hexagonal MoS2 at 14.2, 32.8, 36.0, and 58.3° which indexed to the (002), (100), (102), and (110) planes of MoS2, respectively (JCPDS No. 37-1492).9,13,15 Two strong peaks at 26.2 and 43.2º correspond to the (002) and (101) reflections of hexagonal graphite, respectively.13,14 SEM images show that the entire surface of CC was uniformly covered by MoS2 nanosheets (Figure S1b) with the thickness ranging from 15 to 24 nm (Figure S1c). MoS2 nanosheets interconnect with each other forms a network-like array with obvious ripples and corrugations (Figure S1c). The stoichiometric ratio (S:Mo) estimated from integrated peak area of XPS spectra is close to 2.04 (Figure S2), suggesting the structure is MoS2.13 Figure S3 presents the XRD pattern of MoS2/CC after Ni


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electrodeposition with 20 cycles of cyclic voltammetry, showing an additional diffraction peak at 44.5º corresponding to the (111) facet of metallic Ni.27 The Mo 3d, S 2p, Ni 2p, and O 1s regions for MoS2@Ni/CC are detected in XPS spectra, as shown in Figure S4. Two characteristic peaks located at binding energies of 228.9 and 231.9 eV are attributed to Mo 3d5/2 and Mo 3d3/2, respectively, confirming the Mo element is mainly present as Mo (IV) in MoS2@Ni/CC.11,28 While a single doublet with 2p3/2 peak at 161.8 eV (Figure S4b) was observed in S 2p region, corresponding to −2 oxidation state for sulfur in MoS2/Ni.17 The broad peak at 168.2 eV is assigned to S6+, implying an inevitable surface oxidation of S species.29 The lower binding energies of 852.7 and 855.5 eV for Ni 2p3/2 peaks in Ni 2p region are assigned to characteristic features of metallic Ni and Ni (II), respectively, and the Ni 2p1/2 peak at 873.2 eV is also corresponded to Ni (II) (Figure S4c).30 The other two values of 860.9 and 879.7 eV at higher binding energies are shakeup type peaks of Ni.31 The occurrence of Ni oxidation was found in O 1s spectrum (Figure S4d).30 The SEM images indicate that the full coverage of CC with MoS2@Ni nanosheets for MoS2@Ni/CC and the thickness boosts to 50-60 nm after Ni deposition on MoS2/CC, as shown in Figure 1a and 1b. Figure 1c presents the low-magnification TEM image for one single MoS2@Ni nanosheet. The typical interfringe distance of 0.20 nm is identified (Figure 1d), which is corresponded to the lattice spacing of the (111) plane of Ni phase.27. Figure 1e shows two distinguished phases: layered MoS2 and crystallized Ni. The interlayer spacing of 0.65 nm between the stripes of MoS2 can be observed (Figure 1e), this spacing is slightly larger than that for bulk MoS2 (0.61 nm).8 The HRTEM images of Figure 1e and Figure S5 confirm that the surface of MoS2 was covered with Ni nanosheets. Moreover, the scanning TEM (STEM) image and corresponding EDX mapping analysis further indicate the homogeneous distribution of Mo, S, and Ni in MoS2@Ni nanosheets. All these observations


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support the formation of the unique structure of MoS2@Ni core/shell nanosheets array on CC. Note that we obtained Ni nanosheets film on CC without the use of MoS2 as support (Figure S6).

Figure 1. (a, b) SEM images of MoS2@Ni/CC. (c) TEM image of MoS2@Ni. HRTEM images of areas marked with (d) black and (e) white rectangle in c. (f) STEM image and EDX elemental mapping images of an individual MoS2@Ni nanosheet, indicating the homogeneous distribution of Mo, S, and Ni.


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The electrocatalytic HER performances of MoS2@Ni/CC, MoS2/CC, and Ni/CC were performed in N2-saturated 1.0 M KOH solution. The commercial Pt/C and bare CC were also examined for comparison. All initial data were iR corrected for reflecting the intrinsic behaviors of catalysts.32 The linear sweep voltammetry (LSV) curve of Pt/C on CC indicates that an overpotential of 42 mV was required to afford the current density of 10 mA cm−2. And, the bare CC can be negligible in catalyzing the HER. The MoS2@Ni/CC (MoS2@Ni loading: 7.8 mg cm2

) exhibits a very small onset potential of 30 mV and produces current densities of 10, 20, and

100 mA cm-2 for HER at overpotentials of 91, 118, and 196 mV, respectively. In sharp contrast, polarization curves of MoS2/CC (MoS2 loading: 4.0 mg cm-2) and Ni/CC (Ni loading: 3.8 mg cm-2) suggest poor HER performances with high onset overpotentials (183 and 167 mV), and overpotentials of 252 and 236 mV are needed to approach the current density of 20 mA cm–2, respectivley. These overpotentials for MoS2@Ni/CC catalyst are superior to the behavior of most reported non-Pt HER catalysts in alkaline media (Table S1). It is worth mentioning that the overpotential needed to drive a certain density of 200 mA cm-2 for MoS2@Ni/CC (253 mV) is much smaller than that of Pt/C (395 mV), indicative of the superior catalytic performance of MoS2@Ni/CC. Tafel plots of these four catalysts were further investigated (Figure 2c). The Tafel slopes of Pt/C loaded on CC and MoS2@Ni/CC are 38 and 89 mV dec-1, respectively. Whereas MoS2/CC and Ni/CC possess much higher Tafel slopes of 112 and 115 mV dec–1, suggesting markedly favourable HER kinetics for MoS2@Ni/CC.33 According to literatures,34,35 the mechanism for alkaline HER is generally considered as the Volmer–Heyrovsky process or Volmer–Tafel pathways (Volmer: H2O + e → Hads + OH–; Heyroxsky: Hads + H2O + e ↔ H2 + OH–; Tafel: Hads + Hads → H2). The value of Tafel slope obtained from experiment is 89 mV dec1

for MoS2@Ni/CC, suggesting the Volmer-Heyrovsky mechanism36 for MoS2@Ni/CC-


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catalyzed HER. By applying the extrapolation method to Tafel plots, exchange current density values (j0) of MoS2@Ni/CC (0.807 mA cm-2), MoS2/CC (0.122 mA cm-2), and Ni/CC (0.122 mA cm-2) are obtained (Figure S7), indicating that MoS2@Ni/CC exhibits the best catalytic performance among these three samples.

Figure 2. (a) Polarization curves of MoS2@Ni/CC, MoS2/CC, Ni/CC, Pt/C, and bare CC in 1.0 M KOH solution with a scan rate of 5 mV s-1, (b) the enlarged polarization curves (a), and (c) the Tafel plots of MoS2@Ni/CC, MoS2/CC, Ni/CC, and Pt/C. The long-term cycling test was conducted in alkaline environment to probe the electrochemical durability of MoS2@Ni/CC electrode. Negligible difference between the curves in shape can be observed from comparing the measured I-V curves (Figure 3a). After cycling test, the SEM images of MoS2@Ni/CC (Figure S8) show that the morphology of nanosheets was well maintained. The surface composition of the electrode after cycling was further analyzed by XPS


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(Figure S9). As shown in Figure S9a and S9b, the characteristic peaks of Mo 3d and S 2s for MoS2@Ni/CC are well preserved. In Ni 2p region, there are still four peaks appeared around 854.8, 872.7, 860.8, and 879.1 eV related to Ni 2p3/2, Ni 2p1/2, and their satellites, respectively (Figure S9c). However, the characteristic peak at 852.7 eV for MoS2@Ni/CC disappeared after 3000 cycles of catalytic reaction, indicating the surface oxides thicken in strongly alkaline condition. Continuous HER tests at constant overpotentials of 130 and 260 mV for MoS2@Ni/CC and MoS2/CC were further demonstrated, respectively (Figure 3b and S10). The corresponding current density of 20.6 mA cm-2 was observed on MoS2@Ni/CC electrode with negligible degradation even after a long period of 50 h (Figure 3b). In contrast, the cathodic current appears 40 % (15.2 mA cm-2) degradation for MoS2/CC after 14 h electrolysis (Figure S10), implying the superior stability of MoS2@Ni/CC over MoS2/CC under HER conditions.

Figure 3. (a) Durability tests of MoS2@Ni/CC electrode: initial curve was compared with the curve collected after 3000 cycles performed at a scan rate of 100 mV s-1 between +0.05 and -0.25 V vs. RHE and (b) potentiostatic electrolysis of MoS2@Ni/CC for 50 h. The applied overpotnetial is 130 mV vs. RHE after iR correction. It is reported that both MoS217 and Ni18 are efficient HER catalysts in alkaline medias. We believe that the superior catalytic activity of MoS2@Ni is attributed to its unique core/shell


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structure which facilitates the synergistical catalysis for HER. To understand this, we further analyze the XPS data for MoS2@Ni. The Ni 2p binding energies of 852.7, 855.5, and 873.2 eV for MoS2@Ni/CC are positively shifted from those for Ni metal (852.5, 854.8, and 872.5 eV) while the S 2p binding energies of 161.8 and 162.8 eV are negatively shifted from element S (162.0 and 163.1 eV) for MoS2/CC, suggesting electron transfer from Ni to S37 and a strong interaction between MoS2 and Ni. Similarly, the binding energies of Mo 3d (228.9 and 231. 9 eV) in MoS2@Ni/CC are also lower than those (229.1 and 232.2 eV) of MoS2/CC, giving another evidence to support the strong interaction between MoS2 and Ni. These results reveal that Ni chemically interacts with MoS2 and promotes the HER activity of MoS2.38 Moreover, the coating of Ni greatly enhances the electronic conductivity and the electrocatalytic HER activity of MoS2/CC (Figure S11). On the other hand, the nanosheets array of MoS2 offers a 3D scaffold to support Ni catalysts for exposing more active sites for HER.37 Estimations of the electrochemically active surface areas (EASA) of MoS2@Ni/CC and Ni/CC were determined from calculating their double-layer capacitances through collected cyclic voltammograms (CVs) (Figure S12a and S12b).37 Indeed, MoS2@Ni/CC exhibits much larger capacitance (267.5 mF cm-2) than the counterpart (9.1 mF cm-2) of Ni/CC (Figure S12c), resulting in the higher surface roughness. To emphasize that deposition of Ni with decreased or increased cycles leads to electrodes that exhibit inferior HER activity (Figure S13). Overpotentials of 280, 273, and 288 mV are required to afford the current density of 100 mA cm-2 for these electrodes obtained with 10, 30, and 40 cycles, respectively. The use of 10 cycles leads to lower Ni loading on MoS2 (MoS2@Ni loading: 5.8 mg cm-2) with higher resistance (Figure S14) and thus decreased catalytic activity than that of using 20 cycles. Although using 30 or 40 cycles can further increase the loading mass of Ni (9.5 and 11.1 mg cm-2 for MoS2@Ni loading, respectively) and


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lower the resistance (Figure S14), the resulting thicker and more compacted Ni deposit will completely bury MoS2 (Figure S15) and make it inaccessible to electrolyte, leading to decreased HER activity. All these observations suggest the synergistic effects of MoS2 and Ni in MoS2@Ni are responsible for its excellent HER activity.

Figure 4. (a) Polarization curves and (b) corresponding Tafel plots of MoS2@Ni/CC in 1.0 M PBS. It should be pointed out that our MoS2@Ni/CC electrode is also highly active for HER in phosphate buffered saline (PBS) solution at pH 7, only requiring overpotential of 140 mV to achieve the current density of 10 mA cm-2 (Figure 4a). In contrast, MoS2/CC and Ni/CC need 337 and 319 mV overpotentials to drive the same current density, indicating their inferior HER activities (Figure S16). The value for MoS2@Ni/CC is much lower than most reported values for non-Pt HER catalysts in neutral electrolyzes, as shown in Table S2. The derived Tafel slope of 154 mV dec-1 (Figure 4b) for MoS2@Ni/CC suggests hydrogen production via the Volmer– Heyrovsky mechanism.36 The MoS2@Ni/CC electrode also exhibits excellent stability under neutral solutions and maintains its catalytic performance for 14 h (Figure 4a and S17).

CONCLUSIONS


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In summary, we described a new class of MoS2@Ni core/shell nanosheets array on CC (MoS2@Ni/CC). The investigation of HER electrocatalytic performances suggests that the unique MoS2@Ni/CC core/shell nanosheets provide significant improvements in activity and durability toward HER over MoS2/CC and Ni/CC under alkaline and neutral condition. The enhanced properties are presumably due to the synergistic effects between MoS2 and Ni.38,39 Therefore, this study will offer exciting new avenues for designing self-supported electrode materials made of transition metal sulfide@transition metal core/shell architectures for water splitting and other applications. ASSOCIATED CONTENT Supporting Information XRD pattern; SEM images; XPS spectra; HRTEM image; Table S1; Nyquist plots; CVs; polarization curves; Table S2. This material is available free of charge via the Internet at http://pubs.acs.org. AUTHOR INFORMATION Corresponding Author [email protected] Notes The authors declare no competing financial interest. ACKNOWLEDGMENT


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This work was supported by the National Natural Science Foundation of China (No. 21435005, No. 21575137). REFERENCES (1)

Nocera, D. G. The Artificial Leaf. Acc. Chem. Res. 2012, 45, 767–776.

(2)

Du, H.; Gu, S.; Liu, R.; Li, C. Tungsten Diphosphide Nanorods as an Efficient Catalyst for Electrochemical Hydrogen Evolution. J. Power Sources 2015, 278, 540–545.

(3)

Walter, M. G.; Warren, E. L.; Mckone, J. R.; Boettcher, S. W.; Mi, Q.; Santori, E. A.; Lewis, N. S. Solar Water Splitting Cells. Chem. Rev. 2010, 110, 6446–6473.

(4)

Gu, S.; Du, H.; Asiri, A. M.; Sun, X.; Li, C. Three-Dimensional Interconnected Network of Nanoporous CoP Nanowires as an Efficient Hydrogen Evolution Cathode. Phys. Chem. Chem. Phys. 2014, 16, 16909–16913.

(5)

Faber, M. S.; Jin, S. Earth-Abundant Inorganic Electrocatalysts and Their Nanostructures for Energy Conversion Applications. Energy Environ. Sci. 2014, 7, 3519–3542.

(6)

Hinnemann, B.; Moses, P. G.; Bonde, J.; Jorgensen, K. P.; Nielsen, J. H.; Horch, S.; Chorkendorff, I.; Norskov, J. K. Biomimetic Hydrogen Evolution: MoS2 Nanoparticles as Catalyst for Hydrogen Evolution. J. Am. Chem. Soc. 2005, 127, 5308–5309.

(7)

Jaramillo, T. F.; Jorgensen, K. P.; Bonde, J.; Nielsen, J. H.; Horch, S.; Chorkendorff, I. Identification of Active Edge Sites for Electrochemical H2 Evolution from MoS2 Nanocatalysts. Science 2007, 317, 100–102.

(8)

Xie, J.; Zhang, H.; Li, S.; Wang, R.; Sun, X.; Zhou, M.; Zhou, J.; Lou, X.; Xie, Y. Detect-Rich MoS2 Ultrathin Nanosheets with Additional Active Edge Sites for Enhanced Electrocatalytic Hydrogen Evolution. Adv. Mater. 2013, 25, 5807–5813.


13


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

(9)

Page 14 of 19

Zhang, L.; Wu, H.; Yan, Y.; Wang, X.; Lou, X. Hierarchical MoS2 Microboxes Constructed by Nanosheets with Enhanced Electrochemical Properties for Lithium Storage and Water Splitting. Energy Environ. Sci. 2014, 7, 3302–3306.

(10)

Huang, J.; Hou, D.; Zhou, Y.; Zhou, W.; Li, G.; Tang, Z.; Li, L.; Chen, S. MoS2 Nanosheets-coated CoS2 Nanowire Arrays on Carbon Cloth as Three-Dimensional Electrodes for Efficient Electrocatalytic Hydrogen Evolution. J. Mater. Chem. A 2015, 3, 22886–22891.

(11)

Chang, Y.; Lin, C.; Chen, T.; Hsu, C.; Lee, Y.; Zhang, W.; Wei, K.; Li, L. Highly Efficient Electrocatalytic Hydrogen Production by MoSx Grown on Graphene-Protected 3D Ni Foams. Adv. Mater. 2013, 25, 756–760.

(12)

Morales-Guio, C. G.; Hu, X. Amorphous Molybdenum Sulfides as Hydrogen Evolution Catalysts. Acc. Chem. Res. 2014, 47, 2671–2681.

(13)

Yu, X.; Hu, H.; Wang, Y.; Chen, H.; Lou, X. Ultrathin MoS2 Nanosheets Supported on N-doped Carbon Nanoboxes with Enhanced Lithium Storage and Electrocatalytic Properties. Angew. Chem. Int. Ed. 2015, 54, 7395–7398.

(14)

Yang, L.; Zhou, W.; Lu, J.; Hou, D.; Ke, Y.; Li, G.; Tang, Z.; Kang, X.; Chen, S. Hierarchical Spheres Constructed by Defect-rich MoS2/Carbon Nanosheets for Efficient Electrocatalytic Hydrogen Evolution. Nano Energy 2016, 22, 490–498.

(15)

Zhou, W.; Zhou, K.; Hou, D.; Liu, X.; Li, G.; Sang, Y.; Liu, H.; Li, L.; Chen, S. ThreeDimensional Hierarchical Frameworks Based on MoS2 Nanosheets Self-Assembled on Graphene Oxide for Efficient Electrocatalytic Hydrogen Evolution. ACS Appl. Mater. Interfaces 2014, 6, 21534–21540.


14

Page 15 of 19

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

(16)


Karunadasa, H. I.; Montalvo, E.; Sun, Y.; Majda, M.; Long, J. R.; Chang, C. J. A Molecular MoS2 Edge Site Mimic for Catalytic Hydrogen Generation. Science 2012, 335, 698–702.

(17)

Cai, J.; Xu, J.; Wang, J.; Zhang, L.; Zhou, H.; Zhong, Y.; Chen, D.; Fan, H.; Shao, H.; Zhang, J.; Cao, C. Fabrication of Three-Dimensional Nanoporous Nickel Film with Tunable Nanoporosity and Their Excellent Electrocatalytic Activities for Hydrogen Evolution Reaction. Int. J. Hydrogen Energy 2013, 38, 934–941.

(18)

Xie, Y.; Li, Y. Preparation of Ni-Doped MoS2 Microphere and Its Superior Electrocatlytic Hydrogen Evolution Ability. Adv. Mater. Res. 2014, 871, 206–210.

(19)

Geng, X.; Wu, W.; Li, N.; Sun, W. W.; Armstrong, J.; Al–hilo, A.; Brozak, M.; Cui, J.; Chen, T. Three-Dimensional Structures of MoS2 Nanosheets with Ultrahigh Hydrogen Evolutin Reacion in Water Reduction. Adv. Funct. Mater. 2014, 24, 6123–6129.

(20)

Kundu, A.; Sahu, J. N.; Redzwan, G.; Hashim, M. A. An Overview of Cathode Material and Catalysts Suitable for Generating Hydrogen in Microbial Electrolysis Cell. Int. J. Hydrogen Energy 2013, 38, 1745–1757.

(21)

Liang, F.; Deng, H.; Zhao, F. Sulfur Pollutants Treatment Using Microbial Fuel Cells from Perspectives of Electrochemistry and Microbiology. Chinese J. Anal. Chem. 2013, 41, 1133–1139.

(22)

Zhang, Y.; Jiang, Z.; Liu, Y. Application of Electrochemically Active Bacteria as Anodic Biocatalyst in Microbial Fuel Cells. Chinese J. Anal. Chem. 2015, 43, 155–163.

(23)

Li, H.; Wang, X.; Ding, B.; Pang, G.; Nie, P.; Shen, L.; Zhang, X. Enhance LithiumStorage Performance from Three-Dimensional MoS2 Nanosheets/Carbon Nanotube Paper. ChemElectroChem 2014, 15, 1118–1125.


15


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

(24)

Page 16 of 19

Pu, Z.; Liu, Q.; Asiri, A. M.; Luo, Y.; Sun, X.; He, Y. 3D Macroporous MoS2 Thin Film: In Situ Hydrothermal Preparation and Application as A Highly Active Hydrogen Evolution Electrocatalyst at All pH Values. Electrochim. Acta 2015, 168, 133–138.

(25)

Xing, Z.; Li, Q.; Wang, D.; Yang, X.; Sun, X. Self-Supported Nickel Nitride as An Efficient High-Performance Three-Dimensional Cathode for the Alkaline Hydrogen Evolution Reaction. Electrochim. Acta 2016, 191, 841–845.

(26)

Xing, Z.; Liu, Q.; Xing, W.; Asiri, A. M.; Sun, X. Interconnected Co-Entrapped, NDoped Carbon Nanotube Film as Active Hydrogen Evolution Cathode over the Whole pH Range. ChemSusChem 2015, 8, 1850–1855.

(27)

Cheng,

F.; Chen, J.; Gou, X. MoS2-Ni Nanocomposites as

Catalysts for

Hydrodesulfurization of Thiophene and Thiophene Derivatives. Adv. Mater. 2006, 18, 2561–2564. (28)

Xie, J.; Zhang, J.; Li, S.; Grote, F.; Zhang, X.; Zhang, H.; Wang, R.; Lei, Y.; Pan, B.; Xie, Y. Controllable Disorder Engineering in Oxygen-Incorporated MoS2 Ultrathin Nanosheets for Efficient Hydrogen Evolution. J. Am. Chem. Soc. 2013, 135, 17881– 17888.

(29)

Zhu, H.; Zhang, J.; Yanzhang, R.; Du, M.; Wang, Q.; Gao, G.; Wu, J.; Wu, G.; Zhang, M.; Liu, B.; Yao, J.; Zhang, X. When Cubic Cobalt Sulfide Meets Layered Molybdenum Disulfide: A Core-Shell System Toward Synergetic Electrocatalytic Water Splitting. Adv. Mater. 2015, 27, 4752–4729.

(30)

Biesinger, M. C.; Payne, B. P.; Lau, L. W. M.; Gerson, A.; Smart, R. St. C. X-Ray Photoelectron Spectroscopic Chemical State Quantification of Mixed Nickel Metal, Oxide and Hydroxide Systems. Surf. Interface Anal. 2009, 41, 324–332.


16

Page 17 of 19

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

(31)


Liu, X.; Liu, J.; Sun, X. NiCo2O4@NiO Hybrid Arrays with Improved Electrochemical Performance for Pseudocapacitors. J. Mater. Chem. A 2015, 3, 13900–13905.

(32)

Xing, Z.; Liu, Q.; Asiri, A. M.; Sun, X. Closely Interconnected Network of Molybdenum Phosphide Nanoparticles: A Highly Efficient Electrocatalyst for Generating Hydrogen from Water. Adv. Mater. 2014, 26, 5702–5707.

(33)

Guo, C.; Zhang, L.; Miao, J.; Zhang, J.; Li, C. M. DNA-Functionalized Graphene to Guide Growth of Highly Active Pd Nanocrystals as Efficient Electrocatalyst for Direct Formic Acid Fuel Cells. Adv. Energy Mater. 2013, 3, 167–171.

(34)

Skulason, E.; Tripkovic, V.; Bjorketun, M. E.; Gudmundsdottir, S.; Karlerg, G.; Rossmeisl, J.; Bligaard, T.; Jonsson, H.; Norskov, J. K. Modeling the Electrochemical Hydrogen Oxidation and Evolution Reactions on the Basis of Density Functional Theory Calculations. J. Phys. Chem. C 2010, 114, 18182–18197.

(35)

Subbaraman, R.; Tripkovic, D.; Strmcnik, D.; Chang, K.C.; Uchimura, M.; Paulikas, A.P.; Stamenkovic, V.; Markovic, N. M. Enhancing Hydrogen Evolution Activity in Water Splitting by Tailoring Li+-Ni(OH)2-Pt Interfaces. Science 2011, 334, 1256–1260.

(36)

Conway, B. E.; Tilak, B. V. Interfacial Processes Involving Electrocatalytic Evolution and Oxidation of H2, and the role of chemisorbed H. Electrochim. Acta 2002, 47, 3571– 3594.

(37)

Tian, J.; Liu, Q.; Cheng, N.; Asiri, A. M.; Sun, X. Self-Supported Cu3P Nanowire Arrays as an Integraed High-Performance Three-Dimensional Cathode for Generating Hydrogen from Water. Angew. Chem. Int. Ed. 2014, 53, 9577–9581.


17


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

(38)

Page 18 of 19

Gao, M.; Liang, J.; Zheng, Y.; Xu, Y.; Jiang, J.; Gao, Q.; Li, J.; Yu, S. An Efficient Molybdenum Disulfide/Cobalt Diselenide Hybrid Catalyst for Electrochemical Hydrogen Generation. Nat. Commun. 2015, 6, 5982.

(39)

Gong, M.; Zhou, W.; Tsai, M.; Zhou, J.; Guan, M.; Lin, M.; Zhang, B.; Hu, Y.; Wang, D.; Yang, J.; Pennycook, S. J.; Hwang, B.; Dai, H. Nanoscale Nickel Oxide/Nickel Heterostructures for Active Hydrogen Evolution Electrocatalysis. Nat. Commun. 2014, 5, 4695.


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Table of Contents Graphic


19

Shell Nanosheets

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