Efficient Catalyst For Hydrogen Evolution Reaction Research Articles

Hierarchical NiMo alloy microtubes on nickel foam as an efficient electrocatalyst for hydrogen evolution reaction

Developing efficient, non-noble electrocatalysts for hydrogen evolution reaction (HER) is of high significance for future energy supplement, but challenging. NiMo alloy is a non-noble-metal-based efficient catalyst for HER due to its appropriate hydrogen binding energy and excellent alkali corrosion resistance. Herein, for the first time, we report the preparation of radially aligned NiMo alloy microtubes on Ni foam (NiMo MT/NF). The synthesized NiMo alloy catalyst was composed of the Ni10Mo phase; notably, this hierarchically structured material possessed abundant active sites and a high surface area, and exhibited efficient electronic transport properties. The NiMo MT/NF electrode exhibited a low overpotential of 119 mV at 10 mA/cm2 in a base solution, which was 50 mV less than that of NiMo alloy nanoparticles on NF (169 mV).

Minimum and well-dispersed platinum nanoparticles on 3D porous nickel for highly efficient electrocatalytic hydrogen evolution reaction enabled by atomic layer deposition

Conformal deposition and effective use of catalysts based on 3D electrode architectures are of great importance in electrocatalytic applications. In this work, 3D porous Ni substrate is first fabricated through a hydrogen bubbles dynamic templated method, and well-dispersed Pt nanoparticles are loaded on the substrate subsequently via atomic layer deposition. The 3D porous Ni/Pt is utilized as an efficient hydrogen evolution reaction catalyst. The 3D and high surface area structure is realized through the hydrogen bubbles dynamic templated method. The synergistic effect between atomic-layer-deposited Pt and the 3D structure of porous Ni substrate finds a new approach of minimal yet effective utilization of Pt for much enhanced HER activity. The 3D porous Ni/Pt samples show comparable activity performance with commercial 20 wt% Pt/C. Furthermore, according to the Pt mass-based calculation, only ~0.1 wt% Pt was deposited on 3D porous Ni substrate electrocatalysts which exhibits a much higher activity than the commercial 20 wt% Pt/C catalyst.

Synthesis and mechanism investigation of three-dimensional porous CoP3 nanoplate arrays as efficient hydrogen evolution reaction electrocatalyst

Hydrogen evolution reaction (HER) is one of the key components for the hydrogen-centered renewable clean energy system. Developing efficient HER electrocatalysts that make use of earth-abundant elements is highly desirable yet challenging. Herein, we report a three-dimensional (3-D) CoP3 nanoplate arrays in situ grown on carbon cloth (CoP3 NPAs/CC), which is synthesized by a facile topotactic phosphidation method under hydrothermal condition. As a HER electrocatalyst, the as-prepared CoP3 NPAs/CC exhibit great catalytic activity that is comparable to Pt, over a large pH range of 0–14. At pH = 0, such flexible and efficient CoP3 electrocatalysts can deliver a high current density of 100 mA cm−2 at an overpotential as low as 113 mV, with no apparent activity loss over 40 h. By theoretical calculation and experimental measurements, the outstanding HER performance of the CoP3 NPAs/CC can be attributed to the good conductivity property, synergistic effect between Co and P, unique rich-phosphorous CoP3 nanoplate arrays structure and the great intrinsic catalytic activity. As a highly efficient HER catalyst, CoP3 NPA offers a promising alternative of non-PGM catalysts for electrochemical hydrogen production.

In-situ growth of carbon nanotubes on Ni/NiO nanofibers as efficient hydrogen evolution reaction catalysts in alkaline media

Abstract A novel hierarchical structure of carbon nanotubes grown on Ni/NiO composite nanofiber has been in-situ fabricated by electrospinning and following low-temperature (500 °C) vacuum thermal treatment. During vacuum thermal treatment, decomposition of electrospun nickel acetate/polyvinylpolypyrrolidone precursor nanofibers generate gases as a function of both reducing agents and carbon sources for NiO reduction and carbon nanotubes growth. The thermal treatment processing parameter, i.e. heating rate, controls the morphology and composition of the resulting Ni nanofibers or Ni/NiO‑carbon nanotubes composite nanofibers. This proposed method avoid the usual extra introduction of reducing agents and carbon source. It is a low cost, high yield and safe no-hazard technique. Then, these non-noble metal-based nanofibers are applied as efficient electrocatalysts for the hydrogen evolution reaction in alkaline solution. The Ni/NiO‑carbon nanotubes (10 °C min−1) can drive 10 mA cm−2 at an overpotential of 98 mV in 1 M KOH, which is 52 mV less than for Ni nanofibers. This work offers promising novel catalyst materials in water-splitting devices for large-scale production of hydrogen fuel.

An efficient palm waste derived hierarchical porous carbon for electrocatalytic hydrogen evolution reaction

Replacing precious Pt, Ir, and Pd-metal based catalysts with cost-effective alternatives for hydrogen production via electrocatalytic hydrogen evolution reaction (HER) would benefit significantly towards clean green energy technologies. In this perspective, we demonstrate graphene-like hierarchical porous nanosheets derived from an inexpensive dry spathe-pollen waste of palm plant as an efficient HER catalyst by pursuing “energy from waste” strategy. Investigation of chemical composition and microenvironment by X-ray photoelectron spectroscopy (XPS) confirms the presence of pyridinic, pyrrolic, and graphitic nitrogen innate from N-containing organic components. The textural features with N2 sorption measurements suggests complimentary of high surface area (1297 m2 g‒1), pore volume (0.6 mL g−1), and hierarchical micro/mesoporous architecture which could strongly promote the performance in HER catalysis. Tested as a HER catalyst, the as-prepared carbon material furnish a smaller overpotential (η10) of 0.33 V vs. RHE, at 10.0 mA cm−2 along with a small Tafel slope value of 63 mV dec−1 and long-term stability under acidic medium. The hydrogen binding energy of HPNS and undoped carbon were calculated from DFT studies to support the HPNS activity. Such exquisite properties may be attributed to unique combination of high surface area, facile electrolyte percolation within hierarchical bimodal pore system, robust electrode/electrolyte interface, and N-dopant.

N-doped Mo2C nanoblock for efficient hydrogen evolution reaction

The development of Pt-free electrocatalysts for hydrogen evolution reaction (HER) is still desired in water-splitting as a clean energy. As a highly efficient HER catalyst, Mo-based catalysts have attracted much attention. Annealing is an indispensable part of the preparation of molybdenum-based HER catalysts, but easy to polymerize during carbonization, resulting in lower HER performance of product. Herein, we report the synthesis of molybdenum carbide N&C-doped (Mo2C@CN) with layered mesoporous structure as HER electrocatalyst. This structure can solve the problem of HER performance due to polymerization. The Mo2C@CN is obtained simply by two steps. Benefiting from the structure and doped of N&C, Mo2C@CN exhibits abundant electrochemically active site and outstanding stability. To attain a current density of 10 mA cm−2 in 0.5 M H2SO4, with overpotentials of 202 mV, Tafel slopes of 69 mV dec−1. Little overpotential decay shows its striking stability (2000 cycles) in the acid media.

P doped MoS2 nanoplates embedded in nitrogen doped carbon nanofibers as an efficient catalyst for hydrogen evolution reaction

Two-dimensional (2D) molybdenum sulfide (MoS2) is considered as a promising catalyst for hydrogen evolution reaction (HER), originated from its abundant hydrogen evolution active sites. However, the HER performance of MoS2 is currently hindered by the limited exposed density of the active sites and low conductivity. Herein, we report a facile and scalable electrospinning technique to fabricate 2D MoS2 nanoplates doped with phosphorus within one-dimensional nitrogen doped-carbon nanofibers (NCNFs-MoS2|P) as a highly efficient HER catalyst. The space-confined growth with the presence of NCNFs avoided the stacking and aggregation of the MoS2 nanoplates, resulting in more exposed edge sites. The introduction of phosphorus atoms further activated the surface of MoS2 and enhanced the electron transfer. The overpotential of NCNFs-MoS2|P reached 98 mV at 10 mA cm−2, exhibiting excellent HER catalytic activity. Besides, almost no decay was observed after the stability test (5000 cycles or 20 h). The density functional calculations (DFT) elucidated that the incorporation of phosphorus atoms significantly improved the electrical conductivity and decreased the H adsorption energy barrier on MoS2, leading to a high catalytic performance of NCNFs-MoS2|P.

Microscopic insights into the catalytic mechanisms of monolayer MoS2 and its heterostructures in hydrogen evolution reaction

Exploring high-efficient catalysts for hydrogen evolution reaction (HER) has become very urgent for resolving the energy related issues. Recently, two-dimensional layered MoS2 and its heterostructures with graphene or other traditional photocatalysts have presented great potentials for electrocatalytic and photocatalytic HER applications. On-site investigations of the atomic-scale structures and local electronic properties of the catalytically active sites are the key points for understanding the internal mechanisms, which however are hard to be achieved from the practical systems. Hereby, this review focuses on the recent progresses on the on-site scanning tunneling microscopy/spectroscopy investigations of the atomic structures and electronic properties of the ultrahigh-vacuum deposited and chemical vapor deposition (CVD) synthesized monolayer MoS2 and MoS2/graphene vertical stacks on the electrodes of Au(111) and Au foils. The correlations between the respective HER activities, edge types and edge electronic states are comparatively introduced. Secondly, this review also introduces the photocatalytic HER applications of CVD-grown MoS2/WS2 and WS2/MoS2 vertical stacks on Au foils, mainly considering of their type-II band alignments and the novel interlayer charge transfer behaviors. Finally, future research directions are also proposed for in-depth understanding of the catalytic mechanism, as well as for exploring more efficient HER catalysts.

Co2Ni alloy/N-doped CNTs composite as efficient hydrogen evolution reaction catalyst in alkaline medium

Hydrogen evolution reaction (HER) is a crucial half-reaction of water splitting to produce possible future energy carrier: H2, which is directly associated with the conversion and storage of clean energy. There is a great demand on efficient earth-abundant electrocatalysts to replace Pt, especially in alkaline medium. Herein, we report Co2Ni alloy anchored on nitrogen-doped carbon nanotubes (Co2Ni alloy/N-CNTs) as an efficient alkaline HER electrocatalyst. The alloy is prepared from a straightforward hydrothermal reaction and a post-annealing process in NH3 atmosphere, which in situ reduces the nickel cobalt carbonate hydroxide precursor to alloy and brings N-doping to CNTs without changing original morphology. The as-obtained Co2Ni alloy/N-CNTs hybrids exhibit superior alkaline HER performance with a small Tafel slope of 87 mV dec−1, high exchange current density of 0.8 mA cm−2 and a low overpotential of 100 mV to drive current density of 10 mA cm−2, which is comparable to commercial Pt/C and surpasses numerous reported earth-abundant electrocatalysts. This electrocatalyst can also endure long-time HER process (>24 h). The excellent catalytic performance can be attributed to accelerated charge transfer, more exposed active sites and structural robustness which all benefit from the structural and component configuration that brought by alloy and N-doped CNTs.

(Keynote) One-Pot Synthesis of Manganese Oxides and Cobalt Phosphides Nanohybrids with Abundant Hetero-Interfaces in Amorphous Matrix for Efficient Hydrogen Evolution in Alkaline Solution

Transition metal phosphides (TMPs), albeit promising as hydrogen evolution reaction (HER) catalysts, suffer from the sluggish water dissociation step in alkaline solution, and metal oxides(hydroxides) have been employed to address this problem. However, limited active interface between metal oxides(hydroxides) and phosphides was achieved, leading to unsatisfactory catalytic efficiencies. Therefore, it is still a key challenge to develop a facile way to synthesize the hybrid catalyst of transition metal oxide/phosphide with numerous nanointerfaces. Herein, we report a highly efficient HER catalyst of manganese oxides and cobalt phosphides nanohybrids nanosheets array (denoted as Mn-O@Co-P) with numerous nano-heterointerfaces, facilely grown on carbon cloth (CC) by a simple one-pot process for the first time. The obtained Mn-O@Co-P/CC shows superior activity for HER in alkaline solution with a low overpotential of 96 mV at 10 mA cm-2, a small Tafel slope of 56 mV dec-1 and excellent long-term durability. This work offers a promising one-pot method to synthesize hybrid materials with abundant hetero-nanointerfaces, which is proved to be the powerful strategy for constructing efficient HER catalysts in alkaline solution.

One-step synthesis of nickel oxide/nickel carbide/graphene composite for efficient dye-sensitized photocatalytic H2 evolution

To resolve the energy crisis and environment pollution, it is urgent to explore highly efficient and inexpensive catalysts for hydrogen evolution reaction (HER). In this work, we fabricate nickel oxide/nickel carbide/graphene (labeled as NNG) composite via one-step thermal treatment of NiCl2/graphene oxide (GO) as the precursor at relatively low temperature. GO plays a role of the carbon source to form nickel carbide and increases the distribution of the nickel species. The formed nickel carbide acts as the active sites for hydrogen atoms adsorption (Hads). The NiO contacted with the nickel carbide promotes the Volmer reaction: H2O+e→Hads+OH-. The two different adsorption sites (nickel carbide for Hads, NiO for OH−) jointly lead to the HER synergistic effect in basic solution. The obtained composites exhibit much higher dye-sensitized photocatalytic and electrocatalytic HER activities than nickel carbide, NiO and RGO alone. The highest apparent quantum yield (AQY) of dye-sensitized hydrogen evolution for NNG12 at 420 nm reaches 39.4%. And the electrocatalytic HER overpotential is -0.28 V at the current density of 10 mA cm-2 in 1.0 mol L-1 KOH. To the best of our knowledge, it is the first time to report nickel oxide/nickel carbide as an efficient HER catalyst in alkaline media. This work paves a way for facile and green fabrication of the efficient HER cocatalysts.

Synthesis of popcorn-shaped gallium-platinum (GaPt3) nanoparticles as highly efficient and stable electrocatalysts for hydrogen evolution reaction

The hydrogen evolution reaction (HER) holds great promise for clean energy, where electrocatalysts for HER perform as the cathode reaction of water splitting is the critical reaction process on fuel cell. In spite of the rapid growth of alternative materials, platinum (Pt)-based or platinum alloy materials are still the most efficient catalysts for HER. Here, we report a hot-solvent synthesis for producing pop-corn shaped gallium-platinum (GaPt3) nanoparticles, which exhibits intermetallic behavior with abundant uneven surfaces that guarantee the extensive catalytic active edge sites. The electrochemical catalytic activity of GaPt3-based electrode towards HER was demonstrated for the first time, resulting an outstanding performance of only 27 mV overpotential to achieve the 10 mA/cm2 current density and a Tafel slope of 43.3 mV/dec. (vs. RHE) in acidic media, which is rather superior to that of commercial Pt catalysts and a relatively low overpotential (<80 mV) was obtained even operated at large area (5 cm2). Moreover, cycling tests for 10000-cycle CV sweep (−0.3 to 0.2 V vs. RHE) and durability test for 48 h were applied and the performance remains still, thus giving the confirmation to the long-lasting feature of GaPt3 nanoparticles.

Controllable Synthesis of Nanosized Amorphous MoSx Using Temporally Shaped Femtosecond Laser for Highly Efficient Electrochemical Hydrogen Production

AbstractAmorphous molybdenum sulfide (a‐MoSx) is regarded as a promising electrocatalyst for hydrogen evolution reaction (HER) due to its disorder structures with a significant number of defect‐rich active sites. Here, a green, one‐step, and controllable method is developed to photoregulate the chemical reactions and synthesize nanosized a‐MoSx by temporally shaped femtosecond laser ablation of ammonium tetrathiomolybdate aqueous solution. By adjusting the laser energy and pulse delay to control photoinduced and/or photothermal‐induced reduction/oxidation, the S to Mo ratio x can be modulated from 1.53 to 3.07 and the ratio of the MoV defect species, bridging S22−, and terminal S22− ligands can be controlled. The optimized a‐MoSx catalysts (x = 2.73) exhibit high catalytic activity with a low Tafel slope of 40 mV dec−1, high double‐layer capacitance of 74.47 mF cm−2, and large current density of 516 mA cm−2 at an overpotential of 250 mV. The high catalytic activity can be mainly attributed to MoV defect species and bridging S22− ligands, or most likely dominated by the MoV defect species. This study not only provides an alternatively controllable method to prepare a‐MoSx as efficient HER catalysts but also contributes to the understanding of the origin of its catalytic activity.

Self‐Assembled 3D Hierarchical Porous Hybrid as Platinum‐Like Bifunctional Nonprecious Metal Catalyst toward Oxygen Reduction Reaction and Hydrogen Evolution Reaction

AbstractA class of novel CoNC active nanoparticles anchored on 3D hierarchical porous graphene‐like carbon nanosheets compositions (CoNC@3D HPG) with high porosity, high specific surface area, interconnected pores, and a hierarchical pore structure are synthesized, which are perfect as electrochemical electrode scaffolds, giving rise to efficient and rapid pathways for ion and electron transport, which certainly facilitate the mass transport. This hybrid catalyst possesses outstanding oxygen reduction reaction (ORR) activity through a four‐electron transfer process. Most importantly, the ORR activity of this material is superior to Pt/C catalyst, better stability and fuel (methanol and CO) tolerance than Pt/C catalyst. Besides, the CoNC@3D HPG also exhibits outstanding electrocatalytic performance as an efficient hydrogen evolution reaction catalyst with zero onset overpotential, low overpotential at large current density, small Tafel slope, high exchange current density, and excellent durability. It is worth noting that this outstanding bifunctional catalyst is prepared by a novel resin‐based self‐assembly growth methodology at large‐scale.

Hierarchical MoS2/Ni3S2 core-shell nanofibers for highly efficient and stable overall-water-splitting in alkaline media

Non-noble metal electrocatalysts replacing Pt catalyst for efficient hydrogen-evolution reaction (HER) are highly desired to achieve sustainable production of H2 through water splitting. In this paper, we report a novel ammonium intercalated MoS2/Ni3S2 core-shell nanofibers on graphene-Ni foam by a facile method. Such hierarchical nanostructures provide abundant active sites for hydrogen evolution. Furthermore, DFT calculation demonstrates that the intercalated ammonium ions improve the chemisorption of protons for MoS2, thus further enhancing HER activity. The synthesized MoS2/Ni3S2 nanofiber cathode exhibits an overpotential of 109 mV at 10 mA cm−2 in 1 M KOH electrolyte – the lowest overpotential reported so far among any earth-abundant cathodes working in strong alkaline condition. Combining with a nickel iron layered double hydroxide anode, stable overall water splitting with a low potential of 1.59 V at 10 mA cm−2 is achieved in 1 M KOH for 100 h.

Mechanochemically Assisted Synthesis of a Ru Catalyst for Hydrogen Evolution with Performance Superior to Pt in Both Acidic and Alkaline Media.

Catalysts are at the heart of the hydrogen evolution reaction (HER) for the production of pure and clean hydrogen. For practical applications, the scalable synthesis of efficient HER catalysts, which work in both acidic and alkaline media, is highly desired. In this work, the mechanochemically assisted synthesis of a Ru catalyst with HER performance surpassing Pt in both acidic and alkaline media is reported. Mass production of this Ru catalyst can be achieved via a two-step procedure: the mechanochemical reaction between graphite and dry ice produces edge-carboxylic-acid-functionalized graphene nanoplatelets (CGnP); mixing a Ru precursor and the CGnP in an aqueous medium introduces Ru ions, which coordinate on the CGnP. Subsequent annealing results in uniform Ru nanoparticles (≈2 nm) anchored on the GnP matrix (Ru@GnP). The efficient Ru@GnP catalyst can be easily powered by a single silicon solar cell using a wireless integration device. The self-powered device exhibits robust hydrogen evolution under the irradiation of standard AM 1.5 solar light. This work provides a new opportunity for the low-cost mass production of efficient and stable catalysts for practical applications.

Solvothermal Synthesis of Monodisperse PtCu Dodecahedral Nanoframes with Enhanced Catalytic Activity and Durability for Hydrogen Evolution Reaction

Nanoframes (NFs) with highly open structures have attracted substantial attention because of their large surface area, three-dimensional structure and good stability, which are of significance to enhance the catalytic characters. However, it is still challenging to develop facile and efficient method to construct Pt-based NFs with tailored structures. Herein, a simple solvothermal method was developed to prepare monodisperse PtCu dodecahedral nanoframes (PtCu DNFs), where cetyltrimethylammonium chloride (CTAC) served as the structure-director and dispersing agent, oleylamine as reductant, allantoin as the co-structure-director and coreductant. The PtCu DNFs displayed remarkably improved catalytic performances for hydrogen evolution reaction (HER) in both acid and alkaline electrolytes relative to homemade PtCu nanopolyhedrons (NPHs), commercial Pt/C (20 wt%) and Pt black catalysts. The work offers some instructive guidelines for synthesis of novel metallic NFs as efficient HER catalysts.

CoSe2/WSe2/WO3 hybrid nanowires on carbon cloth for efficient hydrogen evolution reaction

Hydrogen evolution reaction (HER) plays a very important role in energy conversion process. Thus, it is urgent to find high property and low price electrocatalysts for HER. In this work, CoSe2/WSe2/WO3 hybrid nanowires (NWs) on carbon cloth (CC) as a highly efficient HER catalyst is reported at the first time. It can be found that the obtained CoSe2/WSe2/WO3 NWs/CC catalyst exhibits superior catalytic properties toward HER with small onset potential and Tafel slope. To achieve a current density of 10 mA cm−2, CoSe2/WSe2/WO3 NWs/CC only requires an overpotential of 115 mV, which is more outstanding than the WSe2/WO3 NWs/CC. It also shows superior stability with a slight drop in alkaline condition for a duration of 48 h. Such excellent catalytic activity of HER might attribute to the synergistic effect between cobalt (Co) and tungsten (W) elements. The results of all these Experimental performance tests clearly reveal that CoSe2/WSe2/WO3 NWs/CC intrinsically improves HER electrocatalytic activity and thus has potential electrochemical applications in water splitting.

Enhancing Catalytic Activity of MoS2 Basal Plane S-Vacancy By Co Cluster Addition

Electrocatalysts for hydrogen evolution reaction (HER) from water splitting have been widely studied as one of the efficient energy storage methods by producing hydrogen (H2), the important clean energy resource. The best-known electrocatalyst for HER is platinum (Pt) that is expensive and scarce on earth. Molybdenum disulfide (MoS2) has attracted great attentions as one of promising catalysts for replacing Pt not only because of the relatively low cost and earth abundancy but also great HER activity, selectivity and stability as a great catalyst. Since the edge site of MoS2 was proved as an active site for HER, a great number of efforts on maximally exposing edge site have contributed to the studies about MoS2 based catalysts for HER. The basal plane of MoS2 is catalytically inert for HER since the free energy of adsorbed hydrogen (delGH*) known to a great descriptor for activation energy is thermodynamically uphill (~1.92eV) compared with that of active edge site (~0.06eV). However, sulfur (S) vacancy in the basal plane was very recently investigated as a new active site for HER demonstrating the basal plane that composes the majority part of MoS2 can be utilized for HER. Diverse methods to generate S-vacancy to make a use of the basal plane of MoS2 for efficient HER catalysts have been investigated such as Ar plasma treatment, hydrogen annealing and electrochemical desulfurization. However, HER activity of desulfurized MoS2-x still needs to be improved to be competitive with the HER activities of platinum. Cobalt is one of the non-precious metal promotors for MoS2 based catalysts for hydrogen evolution reaction, water gas shift reaction and oxygen reduction reaction. In very recently, Co was doped in the basal plane of S-vacancy rich MoS2 and Co-SMoS2 achieved a great catalytic activity for the hydrodeoxygenation (HDO) reaction. Since S-vacancy site is coordinatively unsaturated and has a high surface free energy like edge site, it is expected to provide a great nucleation site for doping or anchoring transition metal atoms or clusters. Thus, Co promotor can be employed for enhancing the catalytic activity of the basal plane of MoS2 based catalysts. Herein we report the great HER activity enhancement of the catalytically inert basal plane of MoS2 by combining the catalytic effects of S-vacancy and Co cluster addition as a non-precious metal oxide promotor. We use both density functional theory (DFT) calculations and experiments to support the claim. The polycrystalline 2H phase MoS2 multilayer whose basal plane is dominantly exposed was synthesized on fluorine-doped tin oxide (FTO) and carbon foam electrodes through thermolysis in the tube furnace. S-vacancy was generated on the basal plane of MoS2 through the same electrochemical desulfurization method. On top of that, Co cluster was electrodeposited to further promote the HER activity of the basal plane under different desulfurization conditions. Consequently, we demonstrate S-vacancy plays a critical role for Co nucleation during electrodeposition and thus both electrochemically active surface area and the intrinsic catalytic activity increased. Especially, the overpotential at -10 mA/cm2 was reduced around 300mV making the inert basal plane of MoS2 have comparable overpotential about -0.21 V vs. RHE at -10 mA/cm2 with the state of the art non-precious MoS2 based catalysts.

MoS2 Nanosheet Arrays Rooted on Hollow rGO Spheres as Bifunctional Hydrogen Evolution Catalyst and Supercapacitor Electrode

MoS2 has attracted attention as a promising hydrogen evolution reaction (HER) catalyst and a supercapacitor electrode material. However, its catalytic activity and capacitive performance are still hindered by its aggregation and poor intrinsic conductivity. Here, hollow rGO sphere-supported ultrathin MoS2 nanosheet arrays (h-rGO@MoS2) are constructed via a dual-template approach and employed as bifunctional HER catalyst and supercapacitor electrode material. Because of the expanded interlayer spacing in MoS2 nanosheets and more exposed electroactive S–Mo–S edges, the constructed h-rGO@MoS2 architectures exhibit enhanced HER performance. Furthermore, benefiting from the synergistic effect of the improved conductivity and boosted specific surface areas (144.9 m2 g−1, ca. 4.6-times that of pristine MoS2), the h-rGO@MoS2 architecture shows a high specific capacitance (238 F g−1 at a current density of 0.5 A g−1), excellent rate capacitance, and remarkable cycle stability. Our synthesis method may be extended to construct other vertically aligned hollow architectures, which may serve both as efficient HER catalysts and supercapacitor electrodes.