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1.
Electrochemical water splitting is a promising approach for producing sustainable and clean hydrogen. Typically, high valence state sites are favorable for oxidation evolution reaction (OER), while low valence states can facilitate hydrogen evolution reaction (HER). However, here we proposed a high valence state of Co3+ in Ni9.5Co0.5−S−FeOx hybrid as the favorable center for efficient and stable HER, while structural analogues with low chemical states showed much worse performance. As a result, the Ni9.5Co0.5−S−FeOx catalyst could drive alkaline HER with an ultra-low overpotential of 22 mV for 10 mA cm−2, and 175 mV for 1000 mA cm−2 at the industrial temperature of 60 °C, with an excellent stability over 300 h. Moreover, this material could work for both OER and HER, with a low cell voltage being 1.730 V to achieve 1000 mA cm−2 for overall water splitting at 60 °C. X-ray absorption spectroscopy (XAS) clearly identified the high valence Co3+ sites, while in situ XAS during HER and theoretical calculations revealed the favorable electron capture at Co3+ and suitable H adsorption/desorption energy around Co3+, which could accelerate the HER. The understanding of high valence states to drive reductive reactions may pave the way for the rational design of energy-related catalysts.  相似文献   

2.
Electrocatalysis is the most promising strategy to generate clean energy H2, and the development of catalysts with excellent hydrogen evolution reaction (HER) performance at high current density that can resist strong alkaline and acidic electrolyte environment is of great significance for practical industrial application. Therefore, a P doped MoS2@Ni3S2 nanorods array (named P-NiMoS) was successfully synthesized through successive sulfuration and phosphorization. P-NiMoS presents a core/shell structure with a heterojunction between MoS2 (shell) and Ni3S2 (core). Furthermore, the doping of P modulates the electronic structure of the P-NiMoS; the electrons transfer from the t2g orbital of Ni element to the eg empty orbital of Mo element through the Ni−S−Mo bond at the Ni3S2 and MoS2 heterojunction, facilitating the hydrogen evolution reaction. As a result, P-NiMoS exhibits excellent HER activity; the overpotential is 290 mV at high current density of 250 mA cm−2 in alkaline electrolyte, which is close to Pt/C (282 mV@250 mA cm−2), and P-NiMoS can stably evolve hydrogen for 48 h.  相似文献   

3.
Facile and large-scale preparation of materials with uniform distributions of ultrafine particles for catalysis is a challenging task, and it is even more difficult to obtain catalysts that excel in both the hydrogen evolution reaction (HER) and hydrogenation, which are the corresponding merging and splitting procedures of hydrogen, respectively. Herein, the fabrication of ultrafine bimetallic PtNi nanoparticles embedded in carbon nanosheets (CNS) by means of in situ self-polymerization and annealing is reported. This bifunctional catalyst shows excellent performance in the hydrogen evolution reaction (HER) and the hydrogenation of p-nitrophenol. Remarkably PtNi bimetallic catalyst with low metal loading (PtNi2@CNS-600, 0.074 wt % Pt) exhibited outstanding HER activity with an overpotential as low as 68 mV at a current density of 10 mA cm−2 with a platinum loading of only 0.612 μgPt cm−2 and Tafel slope of 35.27 mV dec−1 in a 0.5 m aqueous solution of H2SO4, which is comparable to that of the 20 % Pt/C catalyst (31 mV dec−1). Moreover, it also shows superior long-term electrochemical durability for at least 30 h with negligible degradation compared with 20 % Pt/C. In addition, the material with increased loading (mPtNi2@CNS-600, 2.88 % Pt) showed robust catalytic activity for hydrogenation of p-nitrophenol at ambient pressure and temperature. The catalytic activity towards hydrogen splitting is a circumstantial evidence that agrees with the Volmer–Tafel reaction path in the HER.  相似文献   

4.
Developing highly efficient and stable hydrogen production catalysts for electrochemical water splitting (EWS) at industrial current densities remains a great challenge. Herein, we proposed a heterostructure-induced-strategy to optimize the metal-support interaction (MSI) and the EWS activity of Ru-Ni3N/NiO. Density functional theory (DFT) calculations firstly predicted that the Ni3N/NiO-heterostructures can improve the structural stability, electronic distributions, and orbital coupling of Ru-Ni3N/NiO compared to Ru-Ni3N and Ru-NiO, which accordingly decreases energy barriers and increases the electroactivity for EWS. As a proof-of-concept, the Ru-Ni3N/NiO catalyst with a 2D Ni3N/NiO-heterostructures nanosheet array, uniformly dispersed Ru nanoparticles, and strong MSI, was successfully constructed in the experiment, which exhibited excellent HER and OER activity with overpotentials of 190 mV and 385 mV at 1000 mA cm−2, respectively. Furthermore, the Ru-Ni3N/NiO-based EWS device can realize an industrial current density (1000 mA cm−2) at 1.74 V and 1.80 V under alkaline pure water and seawater conditions, respectively. Additionally, it also achieves a high durability of 1000 h (@ 500 mA cm−2) in alkaline pure water.  相似文献   

5.
《化学:亚洲杂志》2017,12(22):2956-2961
Developing efficient non‐noble metal and earth‐abundant electrocatalysts with tunable microstructures for overall water splitting is critical to promote clean energy technologies for a hydrogen economy. Herein, novel three‐dimensional (3D) flower‐like Ni2P composed of mesoporous nanoplates with controllable morphology and high surface area was prepared by a hydrothermal method and low‐temperature phosphidation as efficient electrocatalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Compared with the urchin‐like Nix Py , the 3D flower‐like Ni2P with a diameter of 5 μm presented an efficient and stable catalytic performance in 0.5 m H2SO4, with a small Tafel slope of 79 mV dec−1 and an overpotential of about 240 mV at a current density of 10 mA cm−2 with a mass loading density of 0.283 mg cm−2. In addition, the catalyst also exhibited a remarkable performance for the OER in 1.0 m KOH electrolyte, with an overpotential of 320 mV to reach a current density of 10 mA cm−2 and a small Tafel slope of 72 mV dec−1. The excellent catalytic performance of the as‐prepared Ni2P may be ascribed to its novel 3D morphology with unique mesoporous structure.  相似文献   

6.
The development of Pt-based electrocatalysts with high Pt utilization efficiency toward the hydrogen evolution reaction (HER) is of great significance for the future sustainable hydrogen economy. For rational design of high-performance HER electrocatalyst, the simultaneous consideration of both thermodynamic and kinetic aspects remains greatly challenging. Herein, a simple template-derived strategy is demonstrated for the in situ growth of ultrafine Pt nanoparticles onto Co3O4 nanosheet-assembled microflowers (abbreviated as Pt/Co3O4 microflowers hereafter) by using the pre-fabricated PtCo-based Hofmann coordination polymer as reactive templates. The elaborate preparation of such intriguing hierarchical architecture with well-dispersed tiny Pt nanoparticles, abundant metal/oxide heterointerfaces and open configuration endows the formed Pt/Co3O4 microflowers with high Pt utilization efficiency, rich active sites, lowered energy barrier for water dissociation and expedited reaction kinetics. Consequently, the Pt/Co3O4 microflowers exhibit superior HER activity with a relatively low overpotential of 34 mV to deliver a current density of 10 mA cm−2, small Tafel slope (34 mV dec−1) and outstanding electrochemical stability, representing an attractive electrocatalyst for practical water splitting. What's more, our concept of in situ construction of metal/oxide heterointerfaces may provide a new opportunity to design high-performance electrocatalysts for a variety of applications.  相似文献   

7.
Even though transition-metal phosphides (TMPs) have been developed as promising alternatives to Pt catalyst for the hydrogen evolution reaction (HER), further improvement of their performance requires fine regulation of the TMP sites related to their specific electronic structure. Herein, for the first time, boron (B)-modulated electrocatalytic characteristics in CoP anchored on the carbon nanotubes (B-CoP/CNT) with impressive HER activities over a wide pH range are reported. The HER performance surpasses commercial Pt/C in both neutral and alkaline media at large current density (>100 mA cm−2). A combined experimental and theoretical study identified that the B dopant could reform the local electronic configuration and atomic arrangement of bonded Co and adjacent P atoms, enhance the electrons’ delocalization capacity of Co atoms for high electrical conductivity, and optimize the free energy of H adsorption and H2 desorption on the active sites for better HER kinetics.  相似文献   

8.
A cage-based metal–organic framework (Ni-NKU-101) with biphenyl-3,3’,5,5’-tetracarboxylic acid was synthesized via solvothermal method. Ni-NKU-101 contains two types of cages based on trinuclear and octa-nuclear nickel-clusters that are connected with each other by the 4-connected ligands, to form a 3D framework with a new topology. A mixed-metal strategy was used to synthesize isostructural bimetallic MOFs of MxNi1-x-NKU-101 (M=Mn, Co, Cu, Zn). The electrocatalytic studies showed that the hydrogen evolution reaction (HER) activity of CuxNi1-x-NKU-101 is much higher than that of other MxNi1-x-NKU-101 catalysts in acidic aqueous solution, owing to the synergistic effect of the bimetallic centers. The optimized Cu0.19Ni0.81-NKU-101 has an overpotential of 324 mV at 10 mA cm−2 and a Tafel slope of 131 mV dec−1. The mechanism of HER activity over these bimetallic MOF-based electrocatalysts are discussed in detail.  相似文献   

9.
Interface engineering has been applied as an effective strategy to boost the electrocatalytic performance because of the strong coupling and synergistic effects between individual components. Here, we engineered vertically aligned FeOOH/CoO nanoneedle array with a synergistic interface between FeOOH and CoO on Ni foam (NF) by a simple impregnation method. The synthesized FeOOH/CoO exhibits outstanding electrocatalytic activity and stability for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in an alkaline medium. For the overall water splitting, the bifunctional FeOOH/CoO nanoneedle catalyst requires only a cell voltage of 1.58 V to achieve a current density of 10 mA cm−2, which is much lower than that required for IrO2//Pt/C (1.68 V). The FeOOH/CoO catalyst has been successfully applied for solar cell-driven water electrolysis, revealing its great potential for commercial hydrogen production and solar energy storage.  相似文献   

10.
Hydrogen energy is considered as one of the ideal clean energies for solving the energy shortage and environmental issues, and developing highly efficient electrocatalysts for overall water splitting to produce hydrogen is still a huge challenge. Herein, for the first time, Ru-doped Cu2+1O vertically arranged nanotube arrays in situ grown on Cu foam (Ru/Cu2+1O NT/CuF) are reported and further investigated for their catalytic properties for overall water splitting. The Ru/Cu2+1O NT/CuF presents ultrahigh catalytic activities for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline conditions, and it exhibits a small overpotential of 32 mV at 10 mA cm−2 in the HER, and only needs 210 mV overpotential to achieve a current density of 10 mA cm−2 in the OER. Importantly, the alkaline electrolyzer using Ru/Cu2+1O NT/CuF as a bifunctional electrocatalyst only needs 1.53 V voltage to deliver a current density of 10 mA cm−2, which is much lower than the benchmark of IrO2(+)/Pt(−) counterpart (1.64 V at 10 mA cm−2). The excellent performance of the Ru/Cu2+1O NT/CuF catalyst is attributed to its high conductive substrate and special Ru-doped nanotube structure, which provides a high electrochemical active surface area and 3D gas diffusion channel.  相似文献   

11.
The development of transition-metal-oxides (TMOs)-based bifunctional catalysts toward efficient overall water splitting through delicate control of composition and structure is a challenging task. Herein, the rational design and controllable fabrication of unique heterostructured inter-doped ruthenium–cobalt oxide [(Ru–Co)Ox] hollow nanosheet arrays on carbon cloth is reported. Benefiting from the desirable compositional and structural advantages of more exposed active sites, optimized electronic structure, and interfacial synergy effect, the (Ru–Co)Ox nanoarrays exhibited outstanding performance as a bifunctional catalyst. Particularly, the catalyst showed a remarkable hydrogen evolution reaction (HER) activity with an overpotential of 44.1 mV at 10 mA cm−2 and a small Tafel slope of 23.5 mV dec−1, as well as an excellent oxygen evolution reaction (OER) activity with an overpotential of 171.2 mV at 10 mA cm−2. As a result, a very low cell voltage of 1.488 V was needed at 10 mA cm−2 for alkaline overall water splitting.  相似文献   

12.
The development of high-efficiency, low-cost, and earth-abundant electrocatalysts for overall water splitting remains a challenge. In this work, Ni-modified MoS2 hybrid catalysts are grown on carbon cloth (Ni-Mo-S@CC) through a one-step hydrothermal treatment. The optimized Ni-Mo-S@CC catalyst shows excellent hydrogen evolution reaction (HER) activity with a low overpotential of 168 mV at a current density of 10 mA cm−2 in 1.0 m KOH, which is lower than those of Ni-Mo-S@CC (1:1), Ni-Mo-S@CC (3:1), and pure MoS2. Significantly, the Ni-Mo-S@CC hybrid catalyst also displays outstanding oxygen evolution reaction (OER) activity with a low overpotential of 320 mV at a current density of 10 mA cm−2, and remarkable long-term stability for 30 h at a constant current density of 10 mA cm−2. Experimental results and theoretical analysis based on density functional theory demonstrate that the excellent electrocatalytic performance can be attributed mainly to the remarkable conductivity, abundant active sites, and synergistic effect of the Ni-doped MoS2. This work sheds light on a unique strategy for the design of high-performance and stable electrocatalysts for water-splitting electrolyzers.  相似文献   

13.

In this work, nanoporous Ni3S2 film (Ni3S2/Ni) is in situ synthesized by direct sulfurization of Ni foam under a mild hydrothermal process. Surprisingly, it is found out that the obtained Ni3S2/Ni exhibits outstanding HER activity and excellent stability in acidic electrolyte. The structure and nature of the Ni3S2/Ni are analyzed with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and field emission scanning electron microscope (FE-SEM). On Ni3S2/Ni, the onset potential is only ?6.23 mV (vs. RHE) while the large exchange current density is 790 µA cm?2 and the Tafel slope is 62.47 mV dec?1. The experimental results demonstrate the potential of Ni3S2/Ni for its replacement of Pt-based catalysts.

  相似文献   

14.
The utilization of noble-metal catalysts for the hydrogen evolution reaction (HER) provides an efficient strategy for hydrogen acquisition. However, exploring catalysts with suitable hydrogen binding strength for the HER process is always of great importance, but extremely challenging. In this work, sulfur and phosphor as electron-withdrawing elements were incorporated into carbon nanotube (CNT)-supported Ru catalysts, which were prepared through a facile solution reduction reaction and post thermo treatment. Owing to the suitable electronegativity provided by P and synergistic effects of the carbon nanotubes, the RuP2/CNT achieved a high catalytic performance as a HER electrocatalyst. This may result from the modulation effect of the electronic properties and the depressed adsorption free energy of RuP2. Electrochemical tests present that the RuP2/CNT composite exhibit a small overpotential of 58 mV at 10 mA cm−2 in acidic electrolyte. In a neutral or alkaline environment, the overpotential is 82 and 40 mV, respectively. The RuP2/CNT electrode also possesses stable durability for long-time cycling, suggesting its remarkable property as promising all-pH HER catalyst.  相似文献   

15.
Herein, an ordinary and mass-production approach is reported to synthesize boron (B) and nitrogen (N) co-doped three-dimensional (3D) carbon aerogels (CA) by using glucose and borax as the raw materials by a simple hydrothermal method and then carbonization in NH3 atmosphere. The porous material (BN-CA-900) possesses a large specific surface area (1032 m2 g−1) and high contents of doped pyridinic N and graphitic N. The onset potential (0.91 V vs. reversible hydrogen electrode, RHE), half-wave potential (0.77 V vs. RHE), and current density (5.70 mA cm−2 at 0.2 V vs. RHE) of BN-CA-900 for ORR are similar to those of commercial Pt/C, indicating that BN-CA-900 has a comparable catalytic activity with Pt/C in alkaline media. The number of electron transfer is 3.86–3.99 and the yield of hydrogen peroxide is less than 6.8 %. BN-CA-900 also presents decent catalytic performance in acidic medium. Moreover, the stability and methanol tolerance of BN-CA-900 are superior to commercial Pt/C in both alkaline and acidic media. The prepared BN-CA-900 is a promising candidate that may be applied in other areas, such as the adsorption of pollution, porous conductive electrodes, and lithium-ion batteries.  相似文献   

16.
Benzylamine electrooxidation reaction (BAOR) is a promising route to produce value-added, easy-separated benzonitrile, and effectively hoist H2 production. However, achieving excellent performance in low alkaline medium is a huge challenge. The performance is intimately correlated with effective coupling of HER and BAOR, which can be achieved by manipulating the d-electron structure of catalyst to regulate the active species from water. Herein, we constructed a biphasic Mo0.8Ni0.2N−Ni3N heterojunction for enhanced bifunctional performance toward HER coupled with BAOR by customizing the d-band centers. Experimental and theoretical calculations indicate that charge transfer in the heterojunction causes the upshift of the d-band centers, which one side facilitates to decrease water activation energy and optimize H* adsorption on Mo0.8Ni0.2N for promoting HER activity, the other side favors to more easily produce and adsorb OH* from water for forming NiOOH on Ni3N and optimizing adsorption energy of benzylamine, thus catalyzing BAOR effectively. Accordingly, it shows an industrial current density of 220 mA cm−2 at 1.59 V and high Faradaic efficiencies (>99 %) for H2 production and converting benzylamine to benzonitrile in 0.1 M KOH/0.5 M Na2SO4. This work guides the design of excellent bifunctional electrocatalysts for the scalable production of green hydrogen and value-added products.  相似文献   

17.
To endow all-solid-state asymmetric supercapacitors with high energy density, cycling stability, and flexibility, we design a binder-free supercapacitor electrode by in situ growth of well-distributed broccoli-like Ni0.75Mn0.25O/C solid solution arrays on a flexible and three-dimensional Ni current collector (3D-Ni). The electrode consists of a bottom layer of compressed but still porous Ni foam with excellent flexibility and high electrical conductivity, an intermediate layer of interconnected Ni nanoparticles providing a large specific surface area for loading of active substances, and a top layer of vertically aligned mesoporous nanosheets of a Ni0.75Mn0.25O/C solid solution. The resultant 3D-Ni/Ni0.75Mn0.25O/C cathode exhibits a specific capacitance of 1657.6 mF cm−2 at 1 mA cm−2 and shows no degradation of the capacitance after 10 000 cycles at 3 mA cm−2. The assembled 3D-Ni/Ni0.75Mn0.25O/C//activated carbon asymmetric supercapacitor has a high specific capacitance of 797.7 mF cm−2 at 2 mA cm−2 and an excellent cycling stability with 85.3 % of capacitance retention after 10 000 cycles at a current density of 3 mA cm−2. The energy density and power density of the asymmetric supercapacitor are up to 6.6 mW h cm−3 and 40.8 mW cm−3, respectively, indicating a fairly promising future of the flexible 3D-Ni/Ni0.75Mn0.25O/C electrode for efficient energy storage applications.  相似文献   

18.
Electrochemical water splitting to generate molecular hydrogen requires catalysts that are cheap, active, and stable, particularly for alkaline electrolyzers, where the cathodic hydrogen evolution reaction is slower in base than in acid even on platinum. Herein, we describe the synthesis of new hollow Chevrel‐phase NiMo3S4 and its alkaline hydrogen evolution reaction (HER) performance: onset potential of ?59 mV, Tafel slope of 98 mV per decade, and exchange current density of 3.9×10?2 mA cm?2. This Chevrel‐phase chalcogenide also demonstrates outstanding long‐term stability under harsh HER cycling conditions. Chevrel‐phase nanomaterials show promise as efficient, low‐cost catalysts for alkaline electrolyzers.  相似文献   

19.
Combining the self-sacrifice of a highly crystalline substance to design a multistep chain reaction towards ultrathin active-layer construction for high-performance water splitting with atmospheric-temperature conditions and an environmentally benign aqueous environment is extremely intriguing and full of challenges. Here, taking cobalt carbonate hydroxides (CCHs) as the initial crystalline material, we choose the Lewis acid metal salt of Fe(NO3)3 to induce an aqueous-phase chain reaction generating free CO32− ions with subsequent instant FeCO3 hydrolysis. The resultant ultrathin (∼5 nm) amorphous Fe-based hydroxide layer on CCH results in considerable activity in catalyzing the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), yielding 10/50 mA ⋅ cm−2 at overpotentials of 230/266.5 mV for OER and 72.5/197.5 mV for HER. The catalysts can operate constantly in 1.0 M KOH over 48 and 45 h for the OER and HER, respectively. For bifunctional catalysis for alkaline electrolyzer assembly, a cell voltage as low as 1.53 V was necessary to yield 10 mA cm−2 (1.7 V at 50 mA cm−2). This work rationally builds high-efficiency electrochemical bifunctional water-splitting catalysts and offers a trial in establishing a controllable nanolevel ultrathin lattice disorder layer through an atmospheric-temperature chemical route.  相似文献   

20.
The synthesis of hybrid platinum materials is fundamental to enable alkaline water electrolysis for cost-effective H2 generation. In this work, we have used a galvanostatic method to co-deposit PtNi films onto polycrystalline gold. The surface concentrations of Ni (ΓNi) and Pt (ΓPt) were calculated from electrochemical measurements; the ΓPtNi ratio and electrocatalytic activity of these materials towards hydrogen evolution reaction (HER) in 1 M KOH show a strong dependence on the current density pulse applied during the electrodeposition. Analysis of the Tafel parameters hints that, on these deposits, HER proceeds through a Volmer-Heyrovsky mechanism. The galvanostatically deposited PtNi layers present a high current output per Pt gram, 3199 A gPt−1, which is significantly larger compared to other PtNi-based materials obtained by more extended and more complex synthesis methods.  相似文献   

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