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1.
Tungsten disulfide (WS2) has attracted much attention as the promising electrocatalyst for hydrogen evolution reaction (HER). Herein, the three-dimensional (3D) structure electrode composed of WS2 and graphene/Ni foam has been demonstrated as the binder-free electrode for highly effective and stable HER. The overpotential of 3D WS2/graphene/Ni is 87 mV at 10 mA cm?2, and the current density is 119.1 mA cm?2 at 250 mV overpotential, indicating very high HER activity. Moreover, the current density of 3D WS2/graphene/Ni at 250 mV only decreases from 119.1 to 110.1 mA cm?2 even after 3000 cycles, indicating a good stability. The high HER performance of 3D WS2/graphene/Ni binder-free electrode is superior than mostly previously reported WS2-based catalysts, which is attributed to the unique graphene-based porous and conductive 3D structure, the high loading of WS2 catalysts and the robust contact between WS2 and 3D graphene/Ni backbones. This work is expected to be beneficial to the fundamental understanding of both the electrocatalytic mechanisms and, more significantly, the potential applications in hydrogen economy for WS2.  相似文献   

2.
Constructing high-performance catalyst for hydrogen evolution reaction (HER) is the effective way to eliminate energy crisis. Reasonable engineering of heterointerfaces can effectively create more active sites and promote electron transfer resulting in improvement in the catalytic activity. In this work, we synthesize the well-defined molybdenum carbides and tungsten carbides nano-heterostructure (Mo2C/W2C) by carbonization with CH4/H2 at 800 °C showing excellent HER activity, fast kinetics and electrochemical stability in both alkaline and acidic electrolytes. Mo2C/W2C requires only 140 and 132 mV overpotentials to reach catalytic current density of 10 mA cm?2 in 0.5 M H2SO4 and 1 M KOH electrolyte, respectively. Tafel slope is as low as 51 and 76 mV dec?1 in 0.5 M H2SO4 and 1 M KOH comparable to the benchmarked Pt/C. Moreover, Mo2C/W2C exhibits a superior stability with slight deterioration in HER performance after 5000 potential cycles. This work elucidates that the rational construction of heterointerfaces is favorable for design of efficient non-noble metal electrocatalyst for HER catalysis.  相似文献   

3.
We have prepared a nanocomposite hybrid film to produce a collaborative network of gold (Au) nanoparticles that are highly dispersed on reduced graphene oxide (RGO) sheets, and tested it for electrocatalytic hydrogen production. The RGO/Au nanocomposite film synthesized on glassy carbon electrode (GCE) allows significant improvements to the electron-transfer process. The Au nanoparticles decorated on the surface of graphene increases the electron density, which synergistically promote the adsorption of hydrogen atoms on the graphene sheets and consequently enhance the hydrogen evolution reaction (HER) activity. The surface properties of the composite was characterized by field-emission scanning electron microscopy (FE-SEM) and the electrocatalytical performances evaluated as-prepared electrocatalyst toward (HER) by linear sweep voltammetry (LSV), Tafel polarization curves and electrochemical impedance spectroscopy (EIS) analyses. The GCE/RGO/Au nanohybrid electrode exhibited good catalytic activity for HER with an onset potential of ?0.3 V and a Tafel slope of 136 mV dec?1, achieving a current density of 10 mA cm?2 at an overpotential of ?0.43 V.  相似文献   

4.
5.
Cu2CoSnS4, Cu2SnS3, Cu2CoS4, Co2SnS3, Cu2S, CoS2, and SnS2 were synthesized using a one-step solvent-free solid-phase approach. The surface structure, morphology, and composition were characterized using an X-ray diffractometer (XRD), Fourier-Transform Infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), and X-ray Photoelectron Spectroscopy (XPS). The characterizations reveal pure phase formation and porous morphology. Further, the Hydrogen evolution reaction was performed using Cu2CoSnS4, Cu2SnS3, Cu2CoS4, Co2SnS3, Cu2S, CoS2, and SnS2-based electrodes. Amid all electrocatalysts, Cu2CoSnS4 shows an excellent hydrogen evolution reaction with a low overpotential of ?192.1 mV at ?10 mA/cm2 in 0.5 M H2SO4. And higher current density. Cu2CoSnS4 also shows a lower Tafel slope of 98.6 mV/dec and charge transfer resistance than mono and bimetallic chalcogenide-based electrodes. The Cu2CoSnS4 exhibit very good stability for ~22 h at ?10 mA/cm2 current density in 0.5 M H2SO4.  相似文献   

6.
The number of exposed active sites in a catalyst plays a key role in determining its catalytic performance. However, the aggregation effect in nanostructured catalysts causes much less reactive sites exposed. In this paper, we report a novel structure of WSe2/rGO with highly exposed WSe2 active edge sites by uniformly imbedding the rGO between each WSe2 nanosheets. With the introduction of rGO, the electron transport property of the WSe2/rGO hybrid structure has also been enhanced. The structure and composition of the samples were investigated by the X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy. Our electrochemical characterizations confirm that the WSe2/rGO hybrid structure exhibits enhanced electrochemical catalytic performance with a Tafel slop of 85 mV/dec for HER, much smaller than that of the pure WSe2.  相似文献   

7.
The electrode with high catalytic activity, low hydrogen overpotential and low cost is desired for hydrogen evolution reaction (HER) via electrocatalytic water splitting. In this study, Pt/Fe-Ni foam (Pt/Fe-NF) electrode was synthesized via cathodic electrodeposition followed by impregnation deposition. Physical and electrochemical properties of Pt/Fe-NF, NF and Pt/NF electrodes were characterized by various techniques. The Pt/Fe-NF electrode exhibited better electrochemical activity for HER under alkaline condition than those of Pt/NF and NF electrodes, owing to the introduction of zero valences Pt and Fe onto the NF, and synergetic effect resulted from the formation of Fe-Ni alloy. Furthermore, Pt/Fe-NF electrode showed extremely high double-layer capacitance (69.1 mFcm?2), suggesting high active sites for the Pt/Fe-NF. Tafel slope of Pt/Fe-NF was 59.9 mV dec?1, indicating that the Volmer-Heyrovsky HER mechanism was the rate-limiting step. The Pt/Fe-NF electrode with great electrocatalytic activity is a promising electro-catalyst for industrial hydrogen production from alkaline electrolyte.  相似文献   

8.
In this work, nickel nanocones (NNCs) were fabricated by single-step electrodeposition method. The NNCs were used as hydrogen evolution electrode and their electrocatalytic activity was compared with pure nickel film. Linear Sweep Voltammetry (LSV), Tafel polarization, Electrochemical Impedance Spectroscopy (EIS), Cyclic Voltammetry (CV) and chronopotentiometry in 1 M KOH were used for study of the electrocatalytic activity for hydrogen evolution reaction (HER). The active surface area was increased by formation of NNCs and hence, the electrocatalytic activity of nickel electrode was improved. Results indicate that the current density corresponding to the amount of evolved hydrogen of NNCs is five times more than pure nickel film formed in the Watts bath.  相似文献   

9.
Amorphous molybdenum sulfide (MoSx) materials have been considered as cheap and promising catalysts for hydrogen evolution reaction (HER). In this contribution, we report that the amorphous MoSx catalysts prepared by the low temperature thermolysis of the (NH4)2MoS4 precursors on carbon clothes (catalyst loading: 3.2 mg/cm2) exhibit a Tefal slope of 50.5 mV/dec and a high exchange current density of 1.5 × 10−3 mA/cm2 in 0.5 M H2SO4 solutions. Spectroscopic studies of the amorphous MoSx catalysts show that the increase of HER efficiency is positively correlated to the concentration of S22− species, providing strong evidence to support the argument that S22− is an active species for electrocatalytic HER. Additionally, the method for preparing catalysts is simple, scalable and applicable for large-scale production.  相似文献   

10.
Recently, the first-row transition metal dichalcogenides MX2 (M = Fe, Co, Ni; X = S, Se) have been widely reported as promising catalysts for hydrogen evolution reaction (HER) because of its excellent catalytic activity and earth-abundance. The rational nanostructure designs have been proved as an effective way to improve their catalytic performance. However, the reported one dimension (1D) NiS2 nanowires for HER suffer from a large Tafel slope. Here, we report a facile synthesis of 1D NiS2 nanowires and its high efficient catalytic activity in HER. This nanowire structure with large surface area and active sites enables highly efficient electrocatalytic performance in HER with a much smaller Tafel slope (83.5 mV/dec) compared to that of bulk NiS2 (136 mV/dec) as well as long-term stability. Our work builds up a structure–performance relationship and enriches the synthetic strategy to other efficient catalysts such as first-row transition metal dichalcogenides or transition metal phosphide.  相似文献   

11.
Hydrogen is considered to be the most promising candidate as a future energy carrier. One of the most used technologies for the electrolytic hydrogen production is alkaline water electrolysis. Electrode materials used in alkaline water electrolysis are mainly made from Ni or Ni-based alloys due to their desirable mechanical and chemical stability in hot and alkaline solution. Considerable research effort has been conducted on enhancement of electrocatalytic activity of Ni electrodes.  相似文献   

12.
The development of cost-effective and high-efficiency electrocatalysts for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) still remains highly challenging. Exposing as many active sites as possible is the key method to improve activity of HER and OER performance. In this communication, we demonstrate a novel 3D hierarchical network NiCo2S4 nanoflake grown on Ni foam (NiCo2S4-NF) as a highly efficient and stable electrochemical catalyst. The NiCo2S4-NF exhibits overpotentials as low as 289 and 409 mV at 100 mA cm?2, superior long-term durability during a 20 h measurement, and a low Tafel slope of 89 and 91 mV dec?1 for HER and OER in 1.0 M NaOH solution. The outstanding performance is owe to the inherent activity of ultrathin NiCo2S4 nanoflakes and the special structure of NiCo2S4-NF that can provide a huge number of exposed active sites, accelerate the transfer of electrons, and facilitate the diffusion of electrolyte simultaneously.  相似文献   

13.
Photocatalytic hydrogen production via water splitting using metal oxide semiconductors has attract great interests because of the two electrons on the kinetics. Pristine Co3O4 was widely studied as efficient photocatalyst, but prefers to produce oxygen due to its lower band-edge positions with regard to water redox potentials. In this work, high efficient photocatalyst basing on non-noble La doped Co3O4 on graphene, i.e., LaxCo3-xO4/G, were first reported and prepared by the microwave hydrothermal synthesis. In this newly developed hybrids, La and Co ions were adsorbed on the surface of graphene (G) and subsequently reacted with ammonia to yield the LaxCo3-xO4/G nanohybrid by in-situ chemical deposition methods. The activity for hydrogen generation of the nanohybrid exhibits 2 times higher than undoped Co3O4/G under visible light irradiation. The H2 evolution of nanohybrid reaches 6.543 mmol g?1 h?1 when the molar ratio of La/Co is 10% in the nanohybrid. Our experimental results indicate the incorporation of La doped in the Co3O4 crystal lattice not only forms the lattice defects, resulting in provision for capture trap and the separation of electrons and holes, but also changes the band structure to eventually improve the photocatalytic activity under visible light. Therefore, non-noble La is a promising substitute to prepare highly efficient hydrogen photocatalyst and can be extendedly applied to the other metal oxide semiconductors for solar hydrogen production.  相似文献   

14.
Hydrogen production from electrocatalytic water splitting is viewed as one of the most promising methods to generate the clean energy. In this work, we successfully prepared an electrode material by growing phosphorus-doped Ni3S2 (PNi3S2) on nickel foam substrate (NF) under hydrothermal conditions. The phosphorus-doping has an obvious effect on the morphology of Ni3S2 on the surface of the nickel foam, which probably results in more active sites, higher electrical conductivity and faster mass transfer. The resulting electrode material displays excellent electrocatalytic activities and stability towards both OER (oxygen evolution reaction) and HER (hydrogen evolution reaction). A relatively low overpotential of 306 mV is required to reach the current density of 100 mA cm?2 for OER and 137 mV at 10 mA cm?2 for HER in 1 M KOH solution. When PNi3S2/NF was used in an electrolyzer for full water splitting, it can generate a current density of 10 mA cm?2 at 1.47 V with excellent stability for more than 20 h.  相似文献   

15.
Ternary Fe-Mo-R (R = Rare Earth metal) crystalline alloys, Fe75Mo20Gd5, Fe75Mo20Dy5, Fe75Mo20Er5 and Fe75Mo20MM5 (MM = mischmetal: 50.2% Ce, 26.3% La, 17.5% Nd, 6.0% Pr, atomic %) have been characterized by means of microstructural and electrochemical techniques in view of their possible applications as electrocatalytic materials for hydrogen evolution reaction (HER). The microstructure of the alloys was examined by scanning electron microscopy coupled with electron probe microanalysis; XRD measurements were also performed. The electrochemical efficiency of the electrodes has been studied on the basis of electrochemical data obtained from steady-state polarization and electrochemical impedance spectroscopy (EIS) techniques in 1 M NaOH solution at 298 K. The results were compared with those obtained on a binary Fe-Mo commercial alloy (Fe80Mo20, atomic %). Moreover, literature data concerning the electrocatalytic activity of the Ni75Mo25 and Co75Mo25 crystalline alloys, which are considered good electrocatalyst materials for the HER, were also reported for comparison. The microstructural features play a fundamental role in determining the electrocatalytic activity of the investigated alloys. The overall experimental data indicate that interesting electrocatalytic performances are displayed by the Fe75Mo20MM5 electrode, which exhibits the highest activity towards the HER.  相似文献   

16.
The urea solution electrolysis has become more attractive than water splitting, because it not only produces clean H2 via the cathodic hydrogen evolution reaction (HER) with lower cell voltage, but also treats sewage containing urea through anodic urea oxidation reaction (UOR). However, lack of efficient electrocatalysts for HER and UOR has limited its development. Herein, hairy sphere -like Ni9S8/CuS/Cu2O composites were synthesized on nickel foam (NF) in situ by a two-step hydrothermal method. The Ni9S8/CuS/Cu2O/NF exhibited good electrocatalytic activity for both HER (?0.146 V vs. RHE to achieve 10 mA cm?2) and UOR (1.357 V vs. RHE to achieve 10 mA cm?2). Based on the bifunctional properties of Ni9S8/CuS/Cu2O/NF, a dual-electrode urea solution electrolytic cell was constructed, which only needed a low voltage of 1.47 V to reach a current density of 10 mA cm?2, and displayed a good stability during a 20-h test. In addition, the reason for the good catalytic activity of Ni9S8/CuS/Cu2O/NF was analyzed and the UOR mechanism was discussed in detail. Our research shows that Ni9S8/CuS/Cu2O/NF is a very promising low-cost dual-function electrocatalyst, which can be used for high-efficiency electrolysis of urea solution to produce hydrogen and treat wastewater.  相似文献   

17.
Replacing Pt by earth abundant catalysts is one of the most important tasks toward potential large-scale HER applications. Among many potential candidates, low cost and earth abundant transition metal dichalcogenides such as MoS2 and WS2 have been promising as good H2 evolution electrocatalysts when they are engineered into the structures with active sites. In this work, we have performed systematic studies on the catalytic reactivity of both MoS2 and WS2 materials produced by one-step and scalable thermolysis from (NH4)2WS4 and (NH4)2MoS4 precursors respectively. Structural analysis shows that these materials prepared at a higher thermolysis temperature exhibit higher crystallinity. The H2 evolution electrocatalysts efficiency for the MoS2 prepared at a lower temperature is higher than those at higher temperatures, where amorphous MoS2 or S22−S22 species instead of crystalline MoS2 is the main active site. By contrast, crystalline WS2 prepared at high temperature is identified to be the key reaction site. Both catalysts display excellent efficiency and durability as an electrocatalyst operating in acidic electrolytes. This work provides fundamental insights for further design and preparation of emergent metal dichalcogenide catalysts, beneficial for the development in clean energy.  相似文献   

18.
Engineering MoS2 catalysts with more active sites and higher conductivity is an effective way to improve its electrochemical activity. Herein, defect-rich amorphous MoSx/carbon nanofiber (CF) arrays on carbon cloth (CC) support (denoted as MoSx/CF/CC) was designed and fabricated, which served as an efficient free-standing electrocatalyst for hydrogen evolution reaction (HER) in acid media. This architecture was beneficial to expose more active catalytic sites and improve the electron/ion transport. In addition, abundant defects altered preferred growth direction of MoSx, resulting in the formation of irregular MoSx particles at the surface of CF arrays. The as-synthesized MoSx/CF/CC-2 exhibited excellent stability and superior HER activity, with a small onset overpotential (107 mV) and low Tafel slope (51 mV dec?1). Such excellent electrochemical performance was attributed to the enriched active sites and shortened charge diffusion distance. This work would pave a new way for rational design and fabrication of defect-rich MoSx-based composite electrode for renewable energy applications.  相似文献   

19.
Pd modified Pt over a novel support of tungsten carbide nanocrystals (the catalyst denotes as PtPd-WC/C) have been prepared by using an intermittent microwave heating (IMH) method. The as-prepared electrocatalysts are characterized by using the techniques of XRD, SEM, TEM, linear sweeping voltammetry and tested for the hydrogen evolution reaction (HER) in the acidic media. It shows a better performance for the HER on PtPd-WC/C electrocatalyst than that on Pt-WC/C electrocatalyst. In addition, these effects on the catalytic activity by changing environmental temperature and electrolyte concentration were taken into account. Kinetic study shows that the HER on the PtPd-WC/C electrocatalyst gives higher exchange current density in H2SO4 solution with high concentration, leading to a lower overpotential and facile kinetics. XRD, SEM and TEM images of PtPd-WC/C show the crystalline features of Pt, Pd and tungsten carbides and indicated the coexistence of these components.  相似文献   

20.
Designing an efficient and stable electrocatalyst made of earth abundant elements to take over expensive noble metal based for Hydrogen Evolution Reaction (HER) have been focused. Cobalt disulfide-molybdenum disulfide nanocomposite supported by nitrogen doped reduced graphene oxide and multiwalled carbon nanotubes (CoS2/MoS2@NrGO-MWCNT) is reported as an efficient electrocatalyst for HER. CoS2/MoS2@N-rGO-MWCNT and ternary hybrids composed of CoS2, MoS2 and N-rGO/MWCNT have been investigated. The catalysts were prepared by facile hydrothermal method, and the optimal doping ratio referred to date cobalt to molybdenum as 2:1 was chosen. It is found that co-existence of CoS2, MoS2 brings abundant active sites and incorporation of MWCNT offered stability. Good dispersion of CoS2 nanoparticles on graphene and MoS2 sheets is observed. Additionally nitrogen doping on rGO sheets has been carried out to boost up the electronegativity of the catalyst as a support to enhance the catalytic activity of CoS2/MoS2 for refine structure and better electrical conductance. Precisely, CoS2/MoS2@N-rGO-MWCNT exhibited smaller tafel slope 73 mV dec?1 at overpotential 281 mV for current density 10 mA cm?2 and the substantial stability of 14 h is recorded in 0.5 M H2SO4 medium, results suggest that catalyst is viable alternate for HER.  相似文献   

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