MXene Hybrid Nanosheets for Superior

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Carbon Coated MoSe2/MXene Hybrid Nanosheets for Superior Potassium Storage Huawen Huang, Jie Cui, Guoxue Liu, Ran Bi, and Lei Zhang ACS Nano, Just Accepted Manuscript • DOI: 10.1021/acsnano.8b09548 • Publication Date (Web): 28 Feb 2019 Downloaded from http://pubs.acs.org on February 28, 2019

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Carbon Coated MoSe2/MXene Hybrid Nanosheets for Superior Potassium Storage Huawen Huang,† Jie Cui,‡ Guoxue Liu,† Ran Bi,† and Lei Zhang*,†

†

School of Chemistry & Chemical Engineering, South China University of Technology,

Guangzhou 510640, P. R. China ‡Analytical

and Testing Centre, South China University of Technology, Guangzhou 510640, P.

R. China

ACS Paragon Plus Environment

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ABSTRACT: Potassium-ion batteries (PIBs) are attracting intensive interest for large-scale applications due to the high nature abundance of potassium source. However, the large radius of K+ makes it difficult for electrode materials to accommodate the repeated K+ insertion/extraction. Thus, developing high-performance electrode materials for PIBs remains a great challenge. Herein, we present a rational design and fabrication of hierarchical carbon coated MoSe2/MXene hybrid nanosheets (MoSe2/MXene@C) as a superior anode material for PIBs. Specifically, the highly conductive MXene substrate can effectively relieve the aggregation of MoSe2 nanosheets and improve the electronic conductivity. Moreover, the carbon layer enables to reinforce the composite structure and further enhance the overall conductivity of the hybrid nanosheets. Meanwhile, strong chemical interactions are found at the interface of MoSe2 nanosheets and MXene flakes, contributing to promoting the charge transfer kinetics and improving the structural durability. Consequently, as an anode material for PIBs, the resulting MoSe2/MXene@C achieves a high reversible capacity of 355 mA h g−1 at 200 mA g−1 after 100 cycles and an outstanding rate performance with 183 mA h g−1 at 10.0 A g−1. The presented design strategy holds great promise for developing more efficient electrode materials for PIBs.

KEYWORDS: molybdenum diselenide, MXene, two-dimensional nanosheets, potassium-ion batteries, chemical interaction


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Nowadays, with the continuing development of electric vehicles and smart power grids, there is ever-increasing demand for next-generation energy storage devices with high energy density and long cyclic life.1‒5 Potassium-ion batteries (PIBs), which possess a similar principle to lithium/sodium-ion batteries, have attracted tremendous attention in large-scale applications due to the high nature abundance of potassium sources.6‒9 Moreover, compared with Na+/Na, K+/K has a lower standard redox potential which can be translated into higher energy density.10,11 However, the large radius of K+ (1.38 Å) makes it difficult for electrode materials to accommodate the repeated K+ insertion/extraction. During the past few years, insertion type materials (e.g., carbonaceous and Ti-based materials)12–16 have attracted much attention for PIBs because of their stable cycling performance. Nevertheless, they often suffer from relatively low theoretical capacities (< 280 mA h g−1). Additionally, although conversion reaction type (e.g., V2O3 and MoS2)17,18 and alloying type (e.g., Sn, Sb, and Bi)19‒21 electrodes have higher theoretical capacities (1000−2000 mA h g−1) for PIBs, they usually confront with huge volume changes upon cycling processes, resulting in structure collapse of active materials and further leading to rapid capacity fading.22 Therefore, designing high-performance electrode materials with robust structure for K+ storage is still a great challenge. Layered transition metal dichalcogenides (LTMDs), a type of two-dimensional (2D) material, have attracted considerable attention as promising electrode materials for PIBs based on conversion reaction mechanism with capacities of ~1000 mA h g−1.23‒27 In particular, molybdenum diselenide (MoSe2), with a sandwich-like lamellar structure, has been widely investigated due to the large interlayer spacing (6.46 Å) that can significantly reduce the structural resistance for K+ insertion/extraction.28‒30 However, due to the high surface energy of 2D nanostructure, MoSe2 nanosheets generally tend to agglomerate, giving rise to rapid capacity


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fading when used as electrode materials. Varied strategies have been proposed to relieve this problem, among which structure engineering is widely practiced.31,32 For example, Guo et al. designed a core/shell nanostructured MoSe2 as an anode material for PIBs, which showed significantly improved cycling stability.33 In addition, except for the afore-mentioned problem, the low intrinsic conductivity of MoSe2 poses another threat to rate performance, especially under high current densities. To address this issue, a common approach is to couple MoSe2 with conductive materials, such as carbonaceous materials, to effectively enhance the conductivity and stability of MoSe2-based electrodes.34‒38 For example, carbon coated MoSe2 nanosheets, in which the MoSe2 were uniformly covered by a conductive carbon layer, exhibited significant improvement of the K+ storage performances.39 In this regard, simultaneously engineering structure and composition of MoSe2-based nanocomposites is supposed to comprehensively overcome related problems, aiming to construct optimal material design toward superior potassium storage properties. By contrast, individual structure or composition optimization strategy can only improve the cyclability of MoSe2-based anode materials to a limited extent. Integrating both above-mentioned strategies, that is, to regulate MoSe2 nanostructures with assistance of other conductive substrate materials is expected to boost the resulting K+ storage performances. MXene, a new graphene-like 2D material identified as transition metal carbide/carbonitrides, has been regarded as a functionalized substrate material for electrochemical energy storage because of its metallic conductivity and rich surface functional groups.40‒44 It is worth mentioning that the surface chemical groups of MXene can act as a basis for the nucleation and thereby anchoring other active materials.45,46 For instance, Qiu et al. reported MoS2 nanoplates on MXene sheets stabilized by a carbon layer, which displayed excellent electrochemical


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properties as an anode material for Li-ion battery.47 The excellent properties could be attributed to the highly conductive functionalized MXene substrate that could effectively relieve the aggregation of MoS2 nanosheets and enhance the conductivity of electrode material. Besides, other active materials such as black phosphorus quantum dots and TiO2 nanorods have also been successfully supported by MXene as improved composite anode materials for Li-ion batteries.48,49 Notwithstanding these advances, the rational design of MXene-based electrode materials for PIBs has rarely been explored and therefore deserving of study. Herein, MoSe2 nanosheets were grown on highly conductive MXene flakes via hydrothermal method, then the as-prepared MoSe2/MXene hybrid nanosheets were coated by a polydopamine (PDA)-derived carbon layer (denoted as MoSe2/MXene@C) to unlock the potassium storage capability. Particularly, the MoSe2 nanosheets were anchored on the MXene substrate vertically to form a hierarchical 2D nanosheets structure, which could effectively prevent the selfaggregation of MoSe2 nanosheets and improve the conductivity of the hybrid material. Furthermore, the carbon coating on the hybrid nanosheets was beneficial to reinforce the hierarchical 2D structure and further enhance the conductivity of the composite. Meanwhile, strong chemical interactions were found at the interface of MoSe2 nanosheets and MXene flakes, contributing to promoting the charge transfer kinetics and improving the structural durability. When evaluated as an anode material for PIBs, the MoSe2/MXene@C showed an ultra-stable cycling performance with high reversible capacity of 355 mA h g−1 at 200 mA g−1 after 100 cycles. Impressively, the composite material demonstrated an outstanding rate performance with 183 mA h g−1 at 10.0 A g−1 and the capacities can be well restored after switching to quondam currents.


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RESULTS AND DISCUSSION The preparation procedures of MoSe2/MXene@C are illustrated in Figure 1. First, MXene flakes are synthesized and used as conductive substrate (see the Experimental Section, Figure S1 in Supporting Information for details). Then, using sodium molybdate as the molybdenum source and Se powder as the selenium source, MoSe2 nanosheets were vertically grown on the surface of MXene flakes through hydrothermal reaction to obtain MoSe2/MXene hybrid nanosheets. Afterward,

the

as-prepared

MoSe2/MXene

was

coated

with

(MoSe2/MXene@PDA) and then annealed in H2/Ar atmosphere at 600

polydopamine oC

to obtain

MoSe2/MXene@C. Specifically, as shown in the atomic model of MoSe2/MXene, MoSe2 nanosheets were anchored on MXene flakes through strong covalent bonds, significantly improving the stability of hybrid structure and promoting the transfer kinetics of ions and electrons during charge/discharge processes. Moreover, the MoSe2/MXene hybrid nanosheets was coated by a uniform carbon layer shown in atomic model of MoSe2/MXene@C, which can effectively reinforce the hierarchical 2D nanostructure and further enhance the overall conductivity. The morphology of the as-prepared materials was characterized by field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The FESEM image of MoSe2/MXene (Figure S2a) shows that the MoSe2 nanosheets are vertically anchored on both sides of MXene flakes. Corresponding TEM image (Figure S2b) and the high-resolution TEM (HRTEM) image (Figure S2c) clearly indicate the hierarchical 2D nanosheets structure of MoSe2/MXene. As shown in Figure 2a, after coated by a PDA-derived carbon layer, the MoSe2/MXene@C has well-preserved hierarchical 2D nanosheets structure similar with that of MoSe2/MXene precursor. The enlarged view of the 2D composite structure (Figure 2b) reveals


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that the MoSe2 nanosheets fully cover the MXene surface to form a three-dimensional interconnected porous network. The successful growth of the ultrathin MoSe2 nanosheets on the surface of MXene is also confirmed in the TEM images (Figure 2c and Figure S3). The HRTEM image (Figure 2d) clearly reveals the lattice fringes with an interlayer spacing about 0.72 nm, attributing to an enlarged (002) lattice planes of MoSe2. Interestingly, it can be obviously observed that the MoSe2 nanosheets is covered by a carbon layer with a thickness of about 2 nm. Additionally, the high-angle annular dark field (HAADF) image (Figure 2e) and the corresponding elemental mapping images (Figure 2f) show an even distribution of the Se, Mo, C and Ti elements in the composite, which suggests that the MoSe2 nanosheets are grown on the surface of MXene flakes uniformly and the carbon layer evenly covers on MoSe2/MXene. Meanwhile, the elemental contents of MoSe2/MXene@C were analyzed through the energy dispersive spectrometer in scanning electron microscopy (SEM-EDS) (Figure S4). And the contents of MoSe2, MXene (Ti3C2) and coated carbon in the hybrid nanosheets can be estimated to be 60.3 wt.%, 6.2 wt.% and 31.2 wt.% based on SEM-DES results and stoichiometry of the elements, respectively. The crystal structure of MoSe2/MXene@C was further analyzed using X-ray diffraction (XRD) pattern. As seen in Figure 3a, all the diffraction peaks could be well indexed to hexagonal MoSe2 (JCPDS 29-0914; space group P63/mmc, a = b = 3.287 Å, c = 12.925 Å). No impurity peak is detectable, implying the pure phase of as-prepared product. The Raman spectrum of MoSe2/MXene@C (Figure S5) confirms the formation of MoSe2 by the two characteristic peaks of A1g and E12g located at 235.1 and 277.8 cm−1, respectively. And the A1g and E12g modes of MoSe2 were exhibited as insets, where A1g mode is preferred for edgeterminated MoSe2 and the in-plane E12g mode is favored for terrace-terminated MoSe2.30


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Additionally, the two strong peaks at 1348.7 cm−1 (D peak) and 1593.6 cm−1 (G peak) of MoSe2/MXene@C respectively correspond to sp3-type and sp2-type of carbon atoms with an intensity ratio of 1.04 (ID/IG), reflecting the existence of disordered carbon in the PDA-derived coating layer. Furthermore, benefiting from the hierarchical 2D nanostructure, the MoSe2/MXene@C exhibits a larger Brunauer-Emmett-Teller (BET) specific surface area of 44.7 m2 g−1 than that of MXene flakes (37.0 m2 g−1) (Figure S6), contributing to facilitating the penetration of the electrolyte and the diffusion of ions.38,47 X-ray photoelectron spectroscopy (XPS) spectra were employed to get insight into the interfacial features between the three components of MoSe2/MXene@C (Figure 3b‒d). In Figure 3b, the survey XPS spectrum of MoSe2/MXene@C testifies the presence of O, Ti, Mo, Se, C, and N elements.34 And the weight percentage of N in the composite is about 3.6 wt.% from the XPS analysis result. Additionally, the high-resolution XPS spectra of Mo 3d, Se 3d, Ti 2p, and N 1s regions are given in Figure S7.32,34,47,50 Specifically, the C 1s spectrum (Figure 3c) is fitted by four peaks at 284.6, 286.4, 288.2, and 282.8 eV.35,36,49 Compared with the C 1s spectrum of MoSe2/MXene (Figure S8), it is evident to reach that the C−Ti bond (282.8 eV) is originated from Ti3C2Tx MXene flakes. As shown in Figure 3d, the O 1s XPS region can be fitted into four peaks located at 530.2, 531.2, 532.0, and 533.3 eV.49,51 Noteworthily, the fitted peak at 532.0 eV could be attributed to Ti−O−Mo bonds, indicating covalent bonds are formed at the interface between MoSe2 nanosheets and MXene flakes, significantly increasing the interaction of the two components.51‒54 Importantly, the strong chemical interactions are desired to enhance the structural durability and improve electrochemical performances.35,47,52 We further investigated the potassium storage performances of MoSe2/MXene@C as an anode material for PIBs. For comparison, MoSe2/MXene without a carbon coating, pure MoSe2 and


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MXene flakes were also prepared as control groups (see the Experimental Section, Figure S1: MXene flakes, Figure S2: MoSe2/MXene, Figure S9: MoSe2, in Supporting Information for details). As depicted in Figure 4a, the first three curves of cyclic voltammograms (CV) profiles of MoSe2/MXene@C were measured in the potential range of 0.01−3.00 V at a scan rate of 0.1 mV s−1. In the first cathodic sweep, three obvious reduction peaks at 0.86 V, 0.72 V and 0.35 V can be clearly seen. The first one (0.86 V) could be associated with the intercalation of K+ insertion into the MoSe2 and the formation of KxMoSe2.34,39 The other two peaks could be corresponded to the further reduction of KxMoSe2 to metallic Mo and K5Se3, and the formation of the solid electrolyte interphase (SEI) layer on the surface, respectively.39 In addition, an obvious peak at 1.70 V is observed in the subsequent anodic sweep, which can be assigned to the oxidation of Mo to MoSe2.39 Notably, the original three peaks disappear and two other new peaks at 1.60 V and 1.15 V emerge in the following cathodic cycles, attributing to the two stages of the reaction from MoSe2 to Mo and K5Se3 mentioned above. The shift of cathodic peak positions is related to the form of SEI film in the first cycle.35,37 And the cathodic and anodic peaks are similar in following scans. Additionally, the charge/discharge processes of MoSe2/MXene@C were further verified by galvanostatic profiles at 200 mA g−1 (Figure S10). The voltages of the discharge/charge plateaus are well consistent with the above results of the CV profiles. Furthermore, the MoSe2/MXene@C electrode delivers an initial discharge specific capacity of 641 mA h g−1 and a charge specific capacity of 347 mA h g−1 with an initial coulombic efficiency (CE) of 54.2%. The low CE of the first cycle can be mainly attributed to the irreversible reaction of SEI film formation during the initial discharge process.35,37 The cycling performance of MoSe2/MXene@C at a current density of 200 mA g−1 is shown in Figure 4b. As an anode material for PIBs, the MoSe2/MXene@C retained a reversible capacity of 355


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mA h g−1 after 100 cycles with a high capacity retention of 99.7% (compared with the second discharge capacity, 356 mA h g−1), revealing a highly stable cycling property. Expect for the first few cycles, stable CE approximate 99% were obtained in the following cycles as well. Meantime, the cycling performances of MoSe2/MXene, MoSe2 and MXene at 200 mA g−1 had also been evaluated. Concretely, MoSe2/MXene delivers a specific capacity of 104 mA h g−1 while pure MoSe2 only exhibits 65 mA h g−1 after 100 cycles. Pure MXene displays a stable but low capacity of 42 mA h g−1. Apparently, these results demonstrate that the rational design of carbon coated MoSe2/MXene could dramatically improve their potassium storage performances as expected. The rate performances of all as-prepared samples were evaluated at varied current densities ranging from 0.1 to 10.0 A g−1 (Figure 4c). As can be seen, the average specific capacities of MoSe2/MXene@C are 350, 324, 294, 270, 246, 230, 212, 198, and 183 mA h g−1 at current densities of 0.1, 0.2, 0.5, 1.0, 2.0, 3.0, 5.0, 7.0, and 10.0 A g−1, respectively. All these results are much better than those of MoSe2/MXene, MoSe2 and MXene, especially under high current densities. Noticeably, it could quickly resume a reversible capacity when the current density changed back to small value (381 mA h g−1 at 0.1 A g−1). Compared with other TMDs anode materials for PIBs, the as-prepared MoSe2/MXene@C shows a high rate performance (Figure S11 and Table S1). In addition, high-rate cycling performance was also measured on the MoSe2/MXene@C anode material. Figure 4d shows the cycling performances at high current density of 1.0, 2.0, and 5.0 A g−1. Impressively, the three cycle curves are very steady with no obvious fluctuation after the second cycle and retain capacities of 317, 243, and 207 mA h g−1 at 1.0, 2.0, and 5.0 A g−1 after 300 cycles, respectively. The excellent rate performance of


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MoSe2/MXene@C is mainly ascribed to the carbon coating and the chemical interfacial interactions toward robust structure and fast electrons/ions transport. The electrochemical properties of MoSe2/MXene@C are better than those of the control groups. To get a deeper understanding of the ultra-stable cycling and rate performances, the morphology of MoSe2/MXene@C after cycling has been analyzed. As shown in Figure S12, the morphology of the as-prepared MoSe2/MXene@C can be well maintained after cycling test, illustrating the excellent structural stability of MoSe2/MXene@C, which is beneficial to exhibit stable cycling and rate performances. Furthermore, the electrochemical impedance spectroscopy (EIS) results of MoSe2/MXene@C, MoSe2/MXene, MoSe2, and MXene were measured and fitted with equivalent circuit to further explain the improved electrochemical properties of MoSe2/[email protected],35 As shown in Figure S13 and Table S2, the MoSe2/MXene@C exhibits smaller surface contact resistance and charge transfer resistance than those of MoSe2/MXene, MoSe2, and MXene, indicating the higher transfer rate of potassium ions during the continuous cycling. To further fully clarify the electrochemical kinetics of the MoSe2/MXene@C electrode, the redox pseudocapacitance-like contribution was analyzed. Figure 5a exhibits the typical CVs at different scan rates ranging from 0.1 to 1.2 mV s−1. The relationship of the peak current (i) and the scan rate (v) obeys a power law:55

i  av b

(1)

the b value can be calculated via the slope of the log(i) versus log(v) plot, where the b value of 0.5 indicates diffusion-controlled behavior and 1.0 represents pseudocapacitive effect. As disclosed in Figure 5b, the b values of the anodic and cathodic peaks are 0.93 and 0.86, respectively, manifesting that the K+ storage kinetics of MoSe2/MXene@C is a combination of


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diffusion-controlled and pseudocapacitive mechanism. The contributions to the capacity can be further quantified by the following equation:55

i  k1v  k 2 v1/2

(2)

1/2 where k1v and k2v represent pseudocapacitive and diffusion-controlled contribution,

respectively (Figure 5c). With increasing of the scan rate, the pseudocapacitive contribution ratio becomes higher and the ratio value reaches 90.2 % at a scan rate of 1.2 mV s−1 (Figure 5d). The high pseudocapacitive contribution of MoSe2/MXene@C is mainly due to its hierarchical 2D nanostructure, which effectively prevents the self-aggregation of MoSe2 nanosheets, further creates a large surface for adsorption/desorption of K+ during the discharge/charge processes.56‒58 Additionally, the high pseudocapacitive contribution is favorable for fast K+ storage kinetics, which contributes to the excellent rate performance. The excellent cycling stability and rate capability of the MoSe2/MXene@C could be attributed to the rationally designed hybrid nanostructure, constructing by the integrated strategy of structure engineering and coupling with conductive materials. Specifically, the hierarchical nanosheets structure with ultrathin 2D nanosheets provides short pathway for K+ diffusion and electron transport, as well as large contact area between the electrode and the electrolyte, leading to the improved cycle stability and rate performance.35,54 It is worth mentioning that the MoSe2 nanosheets form a 3D interconnected porous network on MXene flakes, effectively preventing the self-aggregation of MoSe2 nanosheets, and also creating enough space to accommodate the volume change during repeated K+ insertion/extraction processes.32,34 Furthermore, the carbon layer on the hybrid nanosheets can reinforce the hybrid structure and improve the conductivity of composite. Significantly, strong chemical interactions are found in the interfaces of MoSe2 nanosheets and MXene flakes, which contribute to increasing the transfer kinetics of electrons


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and improving the structural durability. All these features collectively ensure superior potassium storage properties of MoSe2/MXene@C as a promising anode material for PIBs.35,52

CONCLUSIONS In summary, we have rationally designed and constructed a hierarchical 2D nanostructure of carbon coated MoSe2/MXene hybrid nanosheets. With the hierarchical 2D structure, carbon coating and the internal chemical interaction, the as-fabricated MoSe2-based nanocomposite simultaneously integrates the structural and compositional strategies for high performance electrode materials. When tested as an anode material for PIBs, the resulting MoSe2/MXene@C exhibited high specific capacity, excellent rate capability, and excellent cycling stability. The present work provides a successful material design strategy for the development of advanced electrode materials for PIBs, which can be extended to other transition metal chalcogenide based composites as superior anode materials for potassium storage system.

METHODS Preparation of Ti3C2Tx MXene flakes: Ti3C2Tx sheets were synthesized via etching of Ti3AlC2 powder.40 Typically, l.0 g of LiF was dissolved in 20.0 mL of 9.0 M HCl solution. After stirring several minutes, 1.0 g of Ti3AlC2 powder was slowly added into the mixture with magnetic stirring, which was kept stirring at 35 oC for 24 h. Afterward, a black suspension (pH ≈ 6) was obtained after centrifugation and washing with DI-water several times. The resulting suspension was centrifuged at 3000 rpm for 1 h after ultrasonic treatment for 1 h under flowing Ar. Finally,


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the black supernatant, containing the suspension of the Ti3C2Tx (~1.0 mg mL−1), was collected for future use. Preparation of MoSe2/MXene: 79 mg Se powder was dissolved into 5 mL N2H4·H2O (80%) solution by continuously stirring for 1 h. Meantime, 121 mg Na2MoO4·2H2O was dissolved in 20 mL DI-water to obtain a transparent solution. Then, 5 mL prepared Ti3C2Tx MXene suspension was added into the Na2MoO4 solution under stirring and the mixed solution was treated by ultrasonication for 1 h. Subsequently, the Se-N2H4 solution was added to the mixed solution. And the resultant suspension was transferred into a 50 mL Teflon-lined stainless-steel autoclave and heated at 200 oC for 12 h. After cooling to room temperature, the product was collected by centrifugation and washed with DI-water and ethanol. Then, the black precipitate was dried at 60 oC

in vacuum oven overnight and annealed at 600 oC in H2/Ar (8/92, Vol%) for 2 h. In

comparison, pure MoSe2 was prepared in a similar procedure without adding the Ti3C2Tx MXene flakes. Preparation of MoSe2/MXene@C: 45 mg of the unannealed MoSe2/MXene powder was dispersed into 80 mL of Tris-buffer solution (10 mM) by ultrasonic treatment for 1 h. Then, 25 mg of dopamine hydrochloride was added rapidly into the mixture under stirring at room temperature. The black precipitates were collected by centrifugation and washed three times with DI-water after stirring for 3 h. Subsequently, after drying at 60 oC in vacuum, the resulting MoSe2/MXene@PDA was calcined under a H2/Ar (8/92, Vol%) atmosphere at 600 oC for 2 h to obtain MoSe2/MXene@C. Material characterizations: The microstructures were characterized by field-emission scanning electron microscopy (FESEM, SU8220, 10 kV) and transmission electron microscopy (TEM,


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JEOL JEM-2100F, 200 KV). X-ray diffraction (XRD) patterns were acquired via Bruker D8 Advance with Cu Kα radiation (40 kV, 40 mA). X-ray photoelectron spectroscopy (XPS) measurements were conducted on X-ray microprobe of Thermo Escalab 250Xi with monochromatic Al Kα radiation. Raman spectra were collected using LabRAM Aramis with an excitation laser wavelength of λ = 532 nm. The Brunauer-Emmett-Teller (BET) specific surface area of the samples were analyzed in a Micrometrics 3 Flex N2 adsorption-desorption system. Electrochemical measurements: The electrochemical tests were carried out in coin cell configurations (CR2032) at room temperature. The working electrodes consist of active materials (80 wt.%), super P (10 wt.%) and poly-(vinylidene fluoride) (PVDF, 10 wt.%). Copper foil was employed as the current collector and the electrodes were punched into discs with diameter of 8 mm. The mass loading of active material on the electrode is about 1.0 mg cm−2. Fresh potassium foils were used as counter and reference electrodes, and Whatman glass microfiber filters (GF/F) were used as the separators. The electrolyte was 1.0 M potassium bis(fluorosulfonyl)imide (KFSI) in (EC/DEC, 1/1 Vol%). The coin cells were assembled in an Ar-filled glove-box (H2O < 0.1 ppm, O2 < 0.1 ppm). Galvanostatic discharge-charge tests between 0.01 and 3.0 V were performed on NEWARE battery testing system. Cyclic voltammetry (CV) curves were recorded using GAMRY 1000E at different scanning rates. The electrochemical impedance spectroscopy (EIS) was collected at GAMRY 1000E in the frequency range of 105 to 10–2 Hz.


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FIGURES

Figure 1. Schematic of the preparation of MoSe2/MXene@C.


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Figure 2. (a, b) FESEM images at different magnifications, (c) TEM image, (d) HRTEM image, (e) HAADF image and (f) Corresponding mapping images for Se, Mo, C, and Ti elements of MoSe2/MXene@C.


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Figure 3. (a) XRD pattern of MoSe2/MXene@C. (b) XPS survey spectrum and high-resolution spectra of (c) C 1s and (d) O 1s of MoSe2/MXene@C.


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Figure 4. (a) CV curves of MoSe2/MXene@C at a scan rate of 0.1 mV s−1. (b) Comparison of cycle performance of MoSe2/MXene@C, MoSe2/MXene, MoSe2, and MXene at 200 mA g−1 along with corresponding Coulombic efficiency of MoSe2/MXene@C. (c) Comparison of rate performance of MoSe2/MXene@C, MoSe2/MXene, MoSe2, and MXene at various current densities. (d) Long-term cycling discharge capacities and Coulombic efficiencies of MoSe2/MXene@C at the current densities of 1.0 A g−1, 2.0 A g−1, and 5.0 A g−1.


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Figure 5. (a) CV profiles of MoSe2/MXene@C at different scan rates. (b) The plots of log(i) vs. log(υ) (peak current: i, scan rate: υ), calculated from CV curves. (c) The shaded region shows the CV profile with the pseudocapacitive contribution at a scan rate of 1.2 mV s−1. (d) Contribution ratio of pseudocapacitive at different scan rates.


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ASSOCIATED CONTENT Supporting Information. The Supporting Information is available free of charge on the ACS Publications website. Additional SEM, TEM, SEM-EDS, Nitrogen adsorption-desorption isotherm, XPS, XRD, Raman and electrochemical data of the MoSe2/MXene@C, MoSe2/MXene, MoSe2 and MXene. A comparison of MoSe2/MXene@C anode with recently reported TMDs anodes for potassiumion batteries. AUTHOR INFORMATION Corresponding Author *E-mail：[email protected] ORCID Lei Zhang: 0000-0002-6385-5773 Present Addresses School of Chemistry & Chemical Engineering, South China University of Technology, Guangzhou 510640, P. R. China Author Contributions H.H. carried out experiments, analyzed data, and wrote the article; J.C. carried out TEM characterization; G.L. assisted to experiment and data analysis; R.B. and L.Z. planned the project and participated in writing the article.


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ACKNOWLEDGMENT This work was financially supported by the Natural Science Foundation of China (21606088, 51621001), the National Key Research and Development Program of China (2016YFA0202604) and the “Thousand Talents Program”.

REFERENCES (1) Evarts, E. C. To The Limits of Lithium. Nature 2015, 526, 93−95. (2) Zu, C. X.; Li, H. Thermodynamic Analysis on Energy Densities of Batteries. Energy Environ. Sci. 2011, 4, 2614−2624. (3) Armand, M.; Tarascon, J. M. Building Better Batteries. Nature 2008, 451, 652−657. (4) Liu, G. X.; Li, W.; Bi, R.; Etogo, C. A.; Yu, X. Y.; Zhang, L. Cation-Assisted Formation of Porous TiO2−x Nanoboxes with High Grain Boundary Density as Efficient Electrocatalysts for Lithium-Oxygen Batteries. ACS Catal. 2018, 8, 1720−1727. (5) Dunn, B.; Kamath, H.; Tarascon, J. M. Electrical Energy Storage for the Grid: A Battery of Choices. Science 2011, 334, 928−935. (6) Jian, Z.; Luo, W.; Ji, X. Carbon Electrodes for K-Ion Batteries. J. Am. Chem. Soc. 2015, 137, 11566−11569. (7) Luo, W.; Wan, J.; Ozdemir, B.; Bao, W.; Chen, Y.; Dai, J.; Lin, H.; Xu, Y.; Gu, F.; Barone, V.; Hu, L. Potassium Ion Batteries with Graphitic Materials. Nano Lett. 2015, 15, 7671−7677. (8) Eftekhari, A.; Jian, Z.; Ji, X. Potassium Secondary Batteries. ACS Appl. Mater. Interfaces 2017, 9, 4404−4419.


22

Page 23 of 30 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

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(9) Su, D.; McDonagh, A.; Qiao, S. Z.; Wang, G. High-Capacity Aqueous Potassium-Ion Batteries for Large-Scale Energy Storage. Adv. Mater. 2017, 29, 1604007. (10) Xue, L.; Gao, H.; Zhou, W.; Xin, S.; Park, K.; Li, Y.; Goodenough, J. B. Liquid K-Na Alloy Anode Enables Dendrite-Free Potassium Batteries. Adv. Mater. 2016, 28, 9608−9612. (11) Zhang, W.; Mao, J.; Li, S.; Chen, Z.; Guo, Z. Phosphorus-Based Alloy Materials for Advanced Potassium-Ion Battery Anode. J. Am. Chem. Soc. 2017, 139, 3316−3319. (12) Zhang, H.; He, H.; Luan, J.; Huang, X.; Tang, Y.; Wang, H. Adjusting The Yolk-Shell Structure of Carbon Spheres to Boost The Capacitive K+ Storage Ability. J. Mater. Chem. A 2018, 6, 23318‒23325. (13) Jian, Z. L.; Hwang, S.; Li, Z. F.; Hernandez, A. S.; Wang, X. F.; Xing, Z. Y.; Su, D.; Ji, X. L. Hard-Soft Composite Carbon as A Long-Cycling and High-Rate Anode for PotassiumIon Batteries. Adv. Funct. Mater. 2017, 27, 1700324. (14) Jian, Z. L.; Xing, Z. Y.; Bommier, C.; Li, Z. F.; Ji, X. L. Hard Carbon Microspheres: Potassium-Ion Anode versus Sodium-Ion Anode. Adv. Energy Mater. 2016, 6, 1501874. (15) Cao, B.; Zhang, Q.; Liu, H.; Xu, B.; Zhang, S. L.; Zhou, T. F.; Mao, J. F.; Pang, W. K.; Guo, Z. P.; Li, A.; Zhou, J. S.; Chen, X. H.; Song, H. H. Graphitic Carbon Nanocage as A Stable and High Power Anode for Potassium-Ion Batteries. Adv. Energy Mater. 2018, 8, 1801149. (16) Wang, N. N.; Chu, C. X.; Xu, X.; Du, Y.; Yang, J.; Bai, Z. C.; Dou, S. X. Comprehensive New Insights and Perspectives into Ti-Based Anodes for Next-Generation Alkaline Metal (Na+, K+) Ion Batteries. Adv. Energy Mater. 2018, 8, 1801888. (17) Jin, T.; Li, H. X.; Li, Y.; Jiao, L. F.; Chen, J. Intercalation Pseudocapacitance in Flexible and Self-Standing V2O3 Porous Nanofibers for High-Rate and Ultra-Stable K Ion Storage.


23

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Page 24 of 30

Nano Energy 2018, 50, 462−467. (18) Ren, X. D.; Zhao, Q.; McCulloch, W. D.; Wu, Y. Y. MoS2 as A Long-Life Host Material for Potassium Ion Intercalation. Nano Res. 2017, 10, 1313−1321. (19) Sultana, I.; Ramireddy, T.; Rahman, M. M.; Chen, Y.; Glushenkov, A. M. Tin-Based Composite Anodes for Potassium-Ion Batteries. Chem. Commun. 2016, 52, 9279−9282. (20) Han, C. H.; Han, K.; Wang, X. P.; Wang, C. Y.; Li, Q.; Meng, J. S.; Xu, X. M.; He, Q.; Luo, W.; Wu, L. M.; Mai, L. Q. Three Dimensional Carbon Network Confined Antimony Nanoparticles Anode for High Capacity K Ion Batteries. Nanoscale 2018, 10, 6820−6826. (21) Zhang, Q.; Mao, J. F.; Pang, W. K.; Zheng, T.; Sencadas, V.; Chen, Y. Z.; Liu, Y. J.; Guo, Z. P. Boosting the Potassium Storage Performance of Alloy-Based Anode Materials via Electrolyte Salt Chemistry. Adv. Energy Mater. 2018, 8, 1703288. (22) Lei, K.; Wang, C.; Liu, L.; Luo, Y.; Mu, C.; Li, F.; Chen, J. A Porous Network of Bismuth Used as the Anode Material for High-Energy-Density Potassium-Ion Batteries. Angew. Chem. Int. Ed. 2018, 57, 4687−4691. (23) Zhang, X.; Lai, Z.; Ma, Q.; Zhang, H. Novel Structured Transition Metal Dichalcogenide Nanosheets. Chem. Soc. Rev. 2018, 47, 3301−3338. (24) Samadi, M.; Sarikhani, N.; Zirak, M.; Zhang, H.; Zhang, H. L.; Moshfegh, A. Z. Group 6 Transition Metal Dichalcogenide Nanomaterials: Synthesis, Applications and Future Perspectives. Nanoscale Horiz. 2018, 3, 90−204. (25) Fang, Y.; Yu, X.; Lou, X. W. Formation of Polypyrrole-Coated Sb2Se3 Microclips with Enhanced Sodium Storage Properties. Angew. Chem. Int. Ed. 2018, 57, 9859‒9863. (26) Fang, Y.; Yu, X. Y.; Lou, X. W. Formation of Hierarchical Cu-Doped CoSe2 Microboxes via Sequential Ion Exchange for High-Performance Sodium-Ion Batteries. Adv. Mater. 2018,


24

Page 25 of 30 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

ACS Nano

30, 1706668. (27) Liu, Y.; Yu, X.; Fang, Y.; Zhu, X.; Bao, J.; Zhou, X.; Lou, X. W. Confining SnS2 Ultrathin Nanosheets in Hollow Carbon Nanostructures for Efficient Capacitive Sodium Storage. Joule 2018, 2, 725−735. (28) Liu, H.; Guo, H.; Liu, B. H.; Liang, M. F.; Lv, Z. L.; Adair, K. R.; Sun, X. L. Few-Layer MoSe2 Nanosheets with Expanded (002) Planes Confined in Hollow Carbon Nanospheres for Ultrahigh-Performance Na-Ion Batteries. Adv. Funct. Mater. 2018, 28, 1707480. (29) Liu, Y.; Zhu, M. Q.; Chen, D. Sheet-Like MoSe2/C Composites with Enhanced Li-Ion Storage Properties. J. Mater. Chem. A 2015, 3, 11857−11862. (30) Yang, J.; Zhu, J.; Xu, J.; Zhang, C.; Liu, T. MoSe2 Nanosheet Array with Layered MoS2 Heterostructures for Superior Hydrogen Evolution and Lithium Storage Performance. ACS Appl. Mater. Interfaces 2017, 9, 44550−44559. (31) Liu, H.; Liu, B. H.; Guo, H.; Liang, M. F.; Zhang, Y. H.; Borjigin, T.; Yang, X. F.; Wang, L.; Sun, X. L. N-Doped C-Encapsulated Scale-Like Yolk-Shell Frame Assembled by Expanded Planes Few-Layer MoSe2 for Enhanced Performance in Sodium-Ion Batteries. Nano Energy 2018, 51, 639−648. (32) Xie, D.; Xia, X. H.; Zhong, Y.; Wang, Y. D.; Wang, D. H.; Wang, X. L.; Tu, J. P. Exploring Advanced Sandwiched Arrays by Vertical Graphene and N-Doped Carbon for Enhanced Sodium Storage. Adv. Energy Mater. 2017, 7, 1601804. (33) Wang, W.; Jiang, B.; Qian, C.; Lv, F.; Feng, J. R.; Zhou, J. H.; Wang, K.; Yang, C.; Yang, Y.; Guo, S. J. Pistachio-Shuck-Like MoSe2/C Core/Shell Nanostructures for HighPerformance Potassium-Ion Storage. Adv. Mater. 2018, 30, 1801812. (34) Niu, F. E.; Yang, J.; Wang, N. N.; Zhang, D. P.; Fan, W. L.; Yang, J.; Qian, Y. T. MoSe2-


25

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Page 26 of 30

Covered N,P-Doped Carbon Nanosheets as a Long-Life and High-Rate Anode Material for Sodium-Ion Batteries. Adv. Funct. Mater. 2017, 27, 1700522. (35) Zhao, X.; Cai, W.; Yang, Y.; Song, X. D.; Neale, Z.; Wang, H. E.; Sui, J. h.; Cao, G. Z. MoSe2 Nanosheets Perpendicularly Grown on Graphene with Mo–C Bonding for SodiumIon Capacitors. Nano Energy 2018, 47, 224−234. (36) Yang, T.; Liang, J.; Sultana, I.; Rahman, M. M.; Monteiro, M. J.; Chen, Y.; Shao, Z.; Silva, S. R. P.; Liu, J. Formation of Hollow MoS2 Carbon Microspheres for High Capacity and High Rate Reversible Alkali-Ion Storage. J. Mater. Chem. A 2018, 6, 8280−8288. (37) Jia, B. R.; Zhao, Y. Z.; Qin, M. L.; Wang, W.; Liu, Z. W.; Lao, C. Y.; Yu, Q. Y.; Liu, Y.; Wu, H. W.; Zhang, Z. L.; Qu, X. H. Multirole Organic-Induced Scalable Synthesis of A Mesoporous MoS2-Monolayer/Carbon Composite for High-Performance Lithium and Potassium Storage. J. Mater. Chem. A 2018, 6, 11147-11153. (38) Chu, J.; Yu, Q.; Yang, D.; Xing, L.; Lao, C.; Wang, M.; Han, K.; Liu, Z.; Zhang, L.; Du, W.; Xi, K.; Bao, Y.; Wang, W. Thickness-Control of Ultrathin Bimetallic Fe–Mo Selenide@N-Doped Carbon Core/Shell “Nano-Crisps” for High-Performance Potassium-Ion Batteries. Appl. Mater. Today 2018, 13, 344‒351. (39) Ge, J. M.; Fan, L.; Wang, J.; Zhang, Q. F.; Liu, Z. M.; Zhang, E. J.; Liu, Q.; Yu, X. Z.; Lu, B. A. MoSe2/N-Doped Carbon as Anodes for Potassium-Ion Batteries. Adv. Energy Mater. 2018, 8, 1801477. (40) Shahzad, F.; Alhabeb, M.; Hatter, C. B.; Anasori, B.; Man Hong, S.; Koo, C. M.; Gogotsi, Y. Electromagnetic Interference Shielding with 2D Transition Metal Carbides (MXenes). Science 2016, 353, 1137−1140. (41) Anasori, B.; Lukatskaya, M. R.; Gogotsi, Y. 2D Metal Carbides and Nitrides (MXenes) for


26

Page 27 of 30 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

ACS Nano

Energy Storage. Nat. Rev. Mater. 2017, 2, 16098. (42) Ghidiu, M.; Lukatskaya, M. R.; Zhao, M. Q.; Gogotsi, Y.; Barsoum, M. W. Conductive Two-Dimensional Titanium Carbide 'Clay' with High Volumetric Capacitance. Nature 2014, 516, 78−81. (43) Maleski, K.; Mochalin, V. N.; Gogotsi, Y. Dispersions of Two-Dimensional Titanium Carbide MXene in Organic Solvents. Chem. Mater. 2017, 29, 1632−1640. (44) Zeng, C.; Xie, F.; Yang, X.; Jaroniec, M.; Zhang, L.; Qiao, S. Z. Ultrathin Titanate Nanosheets/Graphene Films Derived from Confined Transformation for Excellent Na/K Ion Storage. Angew. Chem. Int. Ed. 2018, 57, 8540−8544. (45) Yu, M. Z.; Zhou, S.; Wang, Z. Y.; Zhao, J. J.; Qiu, J. S. Boosting Electrocatalytic Oxygen Evolution by Synergistically Coupling Layered Double Hydroxide with MXene. Nano Energy 2018, 44, 181−190. (46) Chen, C.; Xie, X. Q.; Anasori, B.; Sarycheva, A.; Makaryan, T.; Zhao, M. Q.; Urbankowski, P.; Miao, L.; Jiang, J. J.; Gogotsi, Y. MoS2-on-MXene Heterostructures as Highly Reversible Anode Materials for Lithium-Ion Batteries. Angew. Chem. Int. Ed. 2018, 57, 1846−1850. (47) Wu, X.; Wang, Z.; Yu, M.; Xiu, L.; Qiu, J. Stabilizing the MXenes by Carbon Nanoplating for Developing Hierarchical Nanohybrids with Efficient Lithium Storage and Hydrogen Evolution Capability. Adv. Mater. 2017, 29, 1607017. (48) Liu, Y. T.; Zhang, P.; Sun, N.; Anasori, B.; Zhu, Q. Z.; Liu, H.; Gogotsi, Y.; Xu, B. SelfAssembly of Transition Metal Oxide Nanostructures on MXene Nanosheets for Fast and Stable Lithium Storage. Adv. Mater. 2018, 30, 1707334. (49) Meng, R. J.; Huang, J. M.; Feng, Y. T.; Zu, L. H.; Peng, C. X.; Zheng, L. R.; Zheng, L.;


27

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Page 28 of 30

Chen, Z. B.; Liu, G. L.; Chen, B. J.; Mi, Y. L.; Yang, J. H. Black Phosphorus Quantum Dot/Ti3C2 MXene Nanosheet Composites for Efficient Electrochemical Lithium/Sodium-Ion Storage. Adv. Energy Mater. 2018, 8, 1801514. (50) Li, D. D.; Zhang, L.; Chen, H. B.; Wang, J.; Ding, L. X.; Wang, S. Q.; Ashman, P. J.; Wang, H. H. Graphene-Based Nitrogen-Doped Carbon Sandwich Nanosheets: A New Capacitive Process Controlled Anode Material for High-Performance Sodium-Ion Batteries. J. Mater. Chem. A 2016, 4, 8630−8635. (51) Halim, J.; Cook, K. M.; Naguib, M.; Eklund, P.; Gogotsi, Y.; Rosen, J.; Barsoum, M. W. XRay Photoelectron Spectroscopy of Select Multi-Layered Transition Metal Carbides (MXenes). Appl. Surf. Sci. 2016, 362, 406−417. (52) Teng, Y.; Zhao, H.; Zhang, Z.; Li, Z.; Xia, Q.; Zhang, Y.; Zhao, L.; Du, X.; Du, Z.; Lv, P.; Swierczek, K. MoS2 Nanosheets Vertically Grown on Graphene Sheets for Lithium-Ion Battery Anodes. ACS Nano 2016, 10, 8526−8535. (53) Li, W.; Bi, R.; Liu, G. X.; Tian, Y. X.; Zhang, L. 3D Interconnected MoS2 with Enlarged Interlayer Spacing Grown on Carbon Nanofibers as A Flexible Anode Toward Superior Sodium-Ion Batteries. ACS Appl. Mater. Interfaces 2018, 10, 26982−26989. (54) Xie, K.; Yuan, K.; Li, X.; Lu, W.; Shen, C.; Liang, C.; Vajtai, R.; Ajayan, P.; Wei, B. Superior Potassium Ion Storage via Vertical MoS2 "Nano-Rose" with Expanded Interlayers on Graphene. Small 2017, 13, 1701471. (55) Wang, J.; Polleux, J.; Lim, J.; Dunn, B. Pseudocapacitive Contributions to Electrochemical Energy Storage in TiO2 (Anatase) Nanoparticles. J. Phys. Chem. C 2007, 111, 14925‒14931. (56) Simon, P.; Gogotsi, Y.; Dunn, B. Where Do Batteries End and Supercapacitors Begin?


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Science 2014, 343, 1210–1211. (57) Chao, D.; Zhu, C.; Yang, P.; Xia, X.; Liu, J.; Wang, J.; Fan, X.; Savilov, S. V.; Lin, J.; Fan, H. J.; Shen, Z. X. Array of Nanosheets Render Ultrafast and High-Capacity Na-Ion Storage by Tunable Pseudocapacitance. Nat. Commun. 2016, 7, 12122. (58) Augustyn, V.; Come, J.; Lowe, M. A.; Kim, J. W.; Taberna, P. L.; Tolbert, S. H.; Abruna, H. D.; Simon, P.; Dunn, B. High-Rate Electrochemical Energy Storage Through Li+ Intercalation Pseudocapacitance. Nat. Mater. 2013, 12, 518–522.


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TABLE OF CONTENTS MoSe2 nanosheets are grown on highly conductive MXene flake via hydrothermal method, which is further coated by a polydopamine-derived carbon layer. Benefitting from the hierarchical 2D structure, carbon coating and strong interfacial interactions, the resulting MoSe2/MXene@C exhibits stable cycling performance and excellent rate capability as an anode material for PIBs.


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MXene Hybrid Nanosheets for Superior

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