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1.
The design and manufacture of effective non-noble metal catalysts for the H2 evolution reaction (HER) are urgent for realizing a cost-effective hydrogen production. We report herein on flower-like structures consisting of NiCoP–CoP heterostructural nanowires grown directly on the hierarchically porous nickel framework (NiCoP–CoP/Ni/NF) to achieve a highly efficient HER in alkaline solution (1.0 M KOH). The NiCoP–CoP/Ni/NF is synthesized by electrodeposition of porous Ni layers on Ni foam, followed by simple hydrothermal reaction and phosphorization. For HER, the binder-free NiCoP–CoP/Ni/NF electrode can reach 10 mA cm?2 current density at a quite low overpotential of 49 mV, because of the combination of porous Ni layers and highly active NiCoP–CoP nanowires. In addition, the NiCoP/CoP heterostructures exhibited remarkable stability under the long-term durability test. This work provides a new strategy that combines electrodeposition and hydrothermal reaction to synthesize effective HER catalysts.  相似文献   

2.
Efficient and sustainable Janus catalysts toward hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are highly desirable for future hydrogen production via water electrolysis. Herein we report an active Janus electrocatalyst of amorphous-crystalline cobalt-molybdenum bimetallic phosphide heterostructured nanosheets on nickel foam (CoMoP/CoP/NF) for efficient electrolysis of alkaline water. As-reported CoMoP/CoP/NF consists of amorphous bimetal phosphide nanosheets doped with crystalline CoMoP/CoP heterostructured nanoparticles on NF. It can efficiently catalyze both HER (η = 127 mV@100 mA cm?2) and OER (η = 308 mV@100 mA cm?2) in alkaline electrolyte with long-term durability. Serving as anode and cathode of water electrolyzer, CoMoP/CoP/NF generates electrolytic current of 10, 50 and 100 mA cm?2 at low voltage of 1.50, 1.59, and 1.67 V, respectively.  相似文献   

3.
Highly active, low-cost, and durable electrocatalysts toward hydrogen evolution reaction (HER) are crucial for electrochemical water splitting. Herein, a green, facial, and effective strategy was proposed to develop CoP on carbon cloth (CoP/o-CC) as efficient self-supported hydrogen evolution electrodes. The designed CoP/o-CC exhibits superior catalytic activity with overpotentials of 118 mV and 95.45 mV to deliver a current density of 10 mA cm?2 in acidic and alkaline solution, respectively, which is superior to most reported studies. In addition, the designed CoP/o-CC electrode also possesses excellent stability even under a large current density of 100 mA cm?2. The origin of significantly enhanced stability thereby was further systematically investigated. Experimental study reveals that the oxygenated functional groups on carbon cloth play the role to bind the CoP electrocatalysts, forming C-O-Co bonds. Thus, the enhanced electrochemical and structural stability of CoP/o-CC is predominantly caused by the interfacial interaction of the C-O-Co bonds between the CoP active materials and surface oxygenated functional groups of carbon fiber. Therefore, we believe that this work provides an in-depth insight into the role of interfacial interaction between the substrate and the catalysts and offers a new methodology to design durable and efficient electrocatalysts.  相似文献   

4.
Developing the novel catalysts with an excellent performance of hydrogen generation is essential to facilitate the application of hydrogen evolution reaction (HER). Herein, a heterostructured cobalt phosphide/nickel phosphide/carbon cloth (CoP/Ni2P/CC) composite was fabricated via an interfacial engineering strategy to achieve the modification of CoP nanoleaf on Ni2P nanosheet skeleton supported by carbon cloth. By virtue of the unique heterostructure, abundant exposing active sites and the synergistic coupling effect of CoP and Ni2P nanoparticles, the elaborated CoP/Ni2P/CC composite exhibits a robust catalytic property. Among fabricated composites, the optimal CoP/Ni2P/CC-4 catalyst behaves an excellent HER performance at a wide pH range (overpotentials of 67, 71 and 95 mV to afford 10 mA cm?2 in 0.5 M H2SO4, 1 M KOH and 1 M PBS, respectively). The HER current density of this composite shows a negligible degradation after continuous test for 24 h. Charmingly, the HER process of this catalyst was innovatively applied to reduce graphene oxide, and thus exploiting the fabrication route of reduced graphene oxide (rGO). We are sure that this work will provide a firm guideline for the exploitation of pH-universal HER catalysts and the exploration of HER application.  相似文献   

5.
Designing cost-effective bifunctional catalysts for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) in alkaline electrolyte remains a significant challenge. Herein, we report adding Nb to pristine CoP nanowires enhances the material's catalytic activities towards HER and OER. Density functional theory (DFT) calculation unravels that the Nb atoms not only optimize hydrogen binding abilities on CoP surface, but also modulate the surface electron densities of in situ formed β-CoOOH during anodic oxidation, thereby greatly accelerate both the HER and OER kinetics in alkaline solutions. In addition, an alkaline electrolyzer using Nb-doped CoP nanowires as cathode and anode for overall water splitting, delivers 100 mA cm?2 at low cell voltage of 1.70 V, superior to Pt//RuO2 couple. This doping strategy can be extended to other transition metal phosphides as multifunctional catalysts towards overall water splitting and beyond.  相似文献   

6.
High-performance, low-cost and robust electrocatalysts for the hydrogen evolution reaction (HER) play a critical role in large-scale hydrogen production via water splitting. Herein, we proposed a synthesis strategy for the self-assembly of maize-like CoP nanorod arrays with abundant active sites via a combination of conventional hydrothermal reaction and low-temperature phosphorization. This unique architecture exhibited remarkable catalytic performance for the HER, with a low overpotential of 130 mV at a current density of 10 mA cm?2 and a small Tafel slope of 59 mV dec?1 in 1.0 M KOH electrolyte, as well as good stability as verified by chronoamperometry measurement for 10 h. Density functional theory calculations further revealed that these maize-like CoP nanorod arrays with dense active sites and a high phosphorization degree could boost the HER performance in terms of low adsorption energy and free energy. This work provided a facile strategy towards manipulating morphology engineering to enhance the HER activity of CoP-based catalysts.  相似文献   

7.
Delicate design and rapid development of low-cost, highly active, and perdurable pH-universal heterogenveous hydrogen evolution reaction (HER) electrocatalysts are demanding challenge in energy-conversion technologies. Herein, heterostructured CoP/MoO2 electrocatalyst was synthesized by employing MoO2 nanorods as framework for the growth of CoP nanoparticles. Owing to the fact that the effective interface of heterostructure can enhance electron transfer/mass diffusion and expose ample active sites, the CoP/MoO2 reveals eminent HER activities with favorable long-term stability in all pH electrolytes, overpotentials of 69, 78, and 165 mV in 0.5 M H2SO4, 1.0 M KOH, and 1.0 M PBS (phosphate-buffered solution) electrolytes were required for CoP/MoO2 to reach the current density of 10 mA cm?2. This work emphasizes that strategy of electronic structure engineering holds great promises in pH-universal HER electrocatalysts for energy storage and conversion.  相似文献   

8.
Transition metal phosphides (TMPs) have attracted considerable attention as an advanced electrocatalyst for hydrogen evolution reaction (HER). Nevertheless, the catalytic efficiency of single-component TMPs is still restricted that cannot endure long-term running and easy to be corroded especially under harsh conditions. In this work, a multicomponent electrocatalyst combined with CoP/Ni2P heteronanoparticles and Co/Ni single-atom active sites (denoted as N–C@CoP/Ni2P) is rational designed and prepared. The obtained N–C@CoP/Ni2P electrode material exhibits enhanced performance with the overpotential of 153 mV at 10 mA cm?2, and the small Tafel value of 53.01 mV dec?1 in 0.5 M H2SO4, and a satisfied result is obtained in basic media as well. The outstanding HER performance is mainly benefiting from the synergistic effect between CoP and Ni2P, and the highly catalytic faction of atomic Co/Ni dual sites. Furthermore, a powerful conductive network fabricated by N-doped carbon skeleton and in-situ grown CNTs improves the conductivity of catalyst. Such a stereoscopic 3D nanostructure is also facile to accelerate the shuttle of electrons and ions.  相似文献   

9.
The growing hydrogen consumption has greatly promoted the development of efficient, stable and low-cost electrocatalysts for the hydrogen evolution reaction (HER). Constructing functional nanostructures is an efficacious strategy to optimize catalytic performance. Herein, we present a feasible route to fabricate distinctive 3D grass-like cobalt phosphide nanocones clad with mini-vesicles on the hierarchically porous Ni foam, which can directly serve as a binder-free electrocatalyst with superior catalytic activity and durability in HER. Thanks to its distinctive 3D microstructure featured with favourable pore-size distribution, abundant active sites provided by mini-vesicles and rapid electron transfer with the assistance of Ni foam, the as-grown grass-like CoP/NF electrocatalyst has shown a favourable overpotential in an acidic solution with an onset overpotential of ∼35 mV, an overpotential of 71 mV at a current density of 10 mA cm−2, reduced by 60 mV in comparison with that realized by urchin-like CoP/NF nanoprickles. Moreover, it has exhibited an excellent HER activity in the alkaline medium, with an overpotential of 117 mV at 10 mA cm−2, a Tafel slope of 63.0 mV dec−1 and a long-term electrochemical durability.  相似文献   

10.
In this work, CoP/NF is synthesized at different temperature (250 °C, 300 °C, 350 °C) (denoted as CoP/NF-T, T = 250, 300, 350). Then, CoP/NF-300 with the best performance towards hydrogen evolution reaction (HER), is used to synthesize compounds with different ratio of reduced graphene oxide (rGO) (CoP/rGO/NF-X, X (quality ratio of rGO/CoP) = 1,3,5). In terms of morphology, under the synergistic effect of rGO, uniform and dense CoP provides the possibility to increase the electrochemical area. While CoP/rGO/NF-3 shows the minimum overpotential of 136 mV to drive 50 mA/cm, and the smallest Tafel slope 135 mV/dec among as-synthesized materials. Furthermore, CoP/rGO/NF-3 has good stability during at least 25 h. These result can be construed as the large electrochemical active area, high conductivity and long-time stability.  相似文献   

11.
Exploring earth-abundant bifunctional electrocatalysts with highly efficient activity for overall water splitting is exceedingly challenging. Herein, a facile electrodeposit-phosphating-electrodeposit strategy is developed to obtain Mo-doped Co(OH)2 nanofilms coupled with CoP nanosheets loaded on nickel foam (denoted as MoCo(OH)2/CoP/NF). Benefitting from the unique structural merits, MoCo(OH)2/CoP/NF exhibits outstanding electrocatalytic performance both for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The results indicate that the dopant of Mo in the Co(OH)2 can further improve the electrocatalytic performance. To achieve a current density of 10 mA cm?2, only 15 and 287 mV are required for HER and OER in 1 M KOH solution, respectively. When MoCo(OH)2/CoP/NF simultaneously employed as cathode and anode for overall water splitting, it only requires 1.593 and 1.853 V to achieve 10 and 50 mA cm?2, respectively. The electrocatalytic activity of MoCo(OH)2/CoP/NF for overall water splitting even exceed the benchmark electrode couple of Pt/C/NF||RuO2/NF, and MoCo(OH)2/CoP/NF perform excellent durability for overall water splitting. This work opens up new avenues for large-scale commercial production of overall water splitting catalysts due to its low-cost and facile method.  相似文献   

12.
Water electrolysis to generate hydrogen (H2) and oxygen (O2) was a sustainable alternative for clean energy in the future but remained challenging. Herein, we fabricated a nanoneedle-like CoP core coated by a P,N-codoped carbon shell (CoP@PNC@NF). The hierarchical structure, unique nanoneedle-like morphology, CoP core, and P,N-codoped carbon shell were responsible for the high electrocatalytic activity. Electrocatalytic tests demonstrated that CoP@PNC@NF displayed low overpotentials of 137.6 and 148.4 mV, as well as Tafel slopes of 59.89 and 56.40 mV dec−1 for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively, at 10 mA cm−2 in 1.0 M KOH. The bifunctional electrocatalyst CoP@PNC@NF also exhibited a low cell voltage of 1.458 V to yield 10 mA cm−2 in the two-electrode system and could maintain the activity for 50 h. The Faradaic efficiencies of CoP@PNC@NF for both HER and OER were nearly 100%. The result outperformed the precious-metal-based electrocatalyst apparatus (RuO2||Pt/C) and other carbon-coated transition-metal phosphides (TMPs). This work paved the way for the rational design of carbon shell-coated TMPs with low energy barriers for converting and storing electrochemical energy.  相似文献   

13.
The development of hydrogen evolution activity (HER) electrocatalyst that can run durably and efficiently under the large current density is of special significance but still challengeable for the massive production of hydrogen. Herein, a CoP/Ni(OH)2 nanowire catalysts grown on Co foam (CF) with a three-dimensional heterojunction structure has been successfully prepared by electrodepositing nickel hydroxide on the surface of cobalt phosphide. The prepared CoP/Ni(OH)2–15 min sample reveals a superior HER activity and stability. It merely requires ultralow overpotentials of 108 and 175 mV to 100 and 500 mA cm?2, respectively. In addition, the long-term stability test shows that the catalyst (CoP/Ni(OH)2–15 min) can operate stably for at least 70 h at 400 mA cm?2. Utilizing NiFe-LDH/IF with high OER activity, the NiFe-LDH/IF || CoP/Ni(OH)2–15 min catalyst system possesses the same outstanding performance for overall water splitting (OWS), which can accomplish ≈ 500 mA cm?2 at 1.74 V in 1 M KOH electrolyte. Moreover, the NiFe-LDH/IF || CoP/Ni(OH)2–15 min couple can work for more than 80 h at 500 mA cm?2, indicating its a great prospect in the area of electrolysis water. Such excellent catalytic performance is mainly attributed to the armor effect of Ni(OH)2, which can not only promote the rapid decomposition of water molecules, but also prevent the loss of phosphorus and enhance the synergistic effect of CoP and Ni(OH)2. This work can offer a significant reference for the design with high-performance and durable transition metal phosphide electrocatalysts.  相似文献   

14.
For the sake of sustainable development, water splitting without other pollutants has been a candidate technology in green energy. Due to the low efficiency of water splitting, innovative breakthroughs are desirable to improve efficiency significantly. Nowadays, the rational design of non-precious metal-based robust bifunctional catalysts is considered to be a feasible way to promote both the cathodic hydrogen evolution reaction (HER) and anodic oxygen evolution reaction (OER). Herein, we proposed a vanadium doped CoP nanorods array catalyst grown on carbon cloth (V–CoP NRs/CC) as a bifunctional electrode material. When V–CoP NRs/CC employed as both anode and cathode materials, it only demands low cell voltages of 1.491 V and 1.606 V to drive a current density of 10 mA cm?2 (j10) and 50 mA cm?2 (j50) in 1 M KOH alkaline electrolyte. Especially, V–CoP NRs/CC can maintain its outstanding electrocatalytic performance for more than 40 h at j50 in overall water splitting.  相似文献   

15.
To achieve high activity and stability for both hydrogen and oxygen evolution reactions through the non-precious-metal based electrocatalysts is still facing the great challenge. Herein, we demonstrate a facile strategy to prepare CoP nanoparticles (NPs) loaded on N, P dual-doped carbon (NPC) electrocatalysts with high concentration N and P dopants through a pyrolysis-deposition-phosphidation process. The great bifunctional electrocatalytic activity for both HER (the overpotential of 98 mV and 86 mV at 10 mA cm−2 in both 0.5 M H2SO4 and 1 M KOH electrolytes, respectively) and OER (the overpotential of 300 mV at 10  mA cm−2 in 1 M KOH electrolyte) were achieved. When CoP@NPC hybrid was used as two electrodes in the 1 M KOH electrolyte system for overall water splitting, the needed cell potential for achieving the current density of 10 mA cm−2 is 1.6 V, and it also showed superior stability for HER and OER after 10 h’ test with almost negligible decay. Experimental results revealed that the P atoms in CoP were the active sites for HER and the CoP@NPC hybrid showed excellent bifunctional electrocatalytic properties due to the synergistic effects between the high catalytic activity of CoP NPs and NPC, in which the doping of N and P in carbon led to a stronger polarization between Co and P in CoP, promoting the charge transfer from Co to P in CoP, enhancing the catalytic activity of P sites and Co sites in CoP for HER and OER, respectively. Specifically, the improvements could result from the changed charge state, the increased active specific surface area, and the facilitated reaction kinetics by N, P co-doping and admixture. This work provides a high-efficient, low-cost and stable electrocatalyst for overall water splitting, and throws light on rational designing high performance electrocatalysts.  相似文献   

16.
Large scale hydrogen generation by water electrolysis is severely impeded by the high cost of noble metal electrode materials and the kinetic-sluggish anodic oxygen evolution reaction (OER). Here we design a MOF-derived NiCoP/CoP/Co3O4 multi-shell hollow nanoflakes as a low-cost cathode electrocatalyst for hydrogen evolution reaction (HER), and replace the OER with more favorable silver oxidation reaction (AOR). The NiCoP/CoP/Co3O4 supported on carbon cloth (CC@NiCoP/CoP/Co3O4) endows an impressive low overpotential (η) of 90 mV at 10 mA cm−2 and a low Tafel slope of 81.7 mV dec−1 for HER in 0.5 M H2SO4 electrolyte. Coupling it with Ag electrode to forming an asymmetric alkali-acid electrolyzer exhibits superior performance with the requirement of a cell voltage of only 1.16 V to attain 10 mA cm−2 with nearly 100% of Faradaic efficiencies for both H2 and Ag2O generation, showing dramatically lower voltage than that previously reported for conventional water splitting systems. In addition, the size and shape of Ag2O can be controlled by manipulating current density. Our electrolyzer design provides not only an economical approach to produce H2 and Ag2O but also shows great promise for expansion into the electrosynthesis of other value-added chemicals.  相似文献   

17.
By increasing demand for hydrogen and oxygen gas for energy and industrial applications, designing a cheap, high-efficiency, and bifunctional electrocatalyst for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) seems necessary. For this purpose Ni–Mo–Fe as a bifunctional electrocatalyst was synthesized by one-step electrodeposition. From this electrocatalyst with optimal composition and current density, a small overpotential of 65, 161 mV for delivering 10, 100 mA/cm2 on HER in alkaline media was achieved. As-fabricated electrode exhibited 344,408 mV for delivering 10, 100 mA/cm2 in OER. Furthermore, this electrocatalyst shows high stability and negligible degradation in overpotential for HER and OER under long term stability tests in alkaline media. The notable function of As-fabricated Ni–Mo–Fe is due to the synergism effect between Ni, Mo, and Fe element and binder-free structure. Owing to the high-performance and high-stability of Ni–Mo–Fe electrocatalyst under Hydrogen and Oxygen evolution reactions is a candidate for industrial uses in the alkaline electrolyzer.  相似文献   

18.
Low-dimensional transition metal dichalcogenides, e.g., MoSe2, are attractive electrocatalysts for hydrogen evolution reactions (HER). However, the stable 2H-phase MoSe2 with semiconducting properties exhibits electrocatalytic performance only at its sheet edges, but the basal planes without defects are inactive, limiting their performance in HER. This work reported a strategy for comprehensive activation of TMDs by intercalating 2D MoSe2 with 2D CoP. Its unique sandwiched structure opens up activity between the layers, enhancing active surface area to 10-fold. Meanwhile, the maximized interfaces enable rapid ion/electron transport and excellent electrical conductivity, thus yielding superior HER activity. It exhibits a very low overpotential of 105 mV at 10 mA cm−2, small Tafel slope of 51 mV dec−1 and excellent electrochemical stability for >24 h. The CoP significantly increases the hydrogen adsorption sites of MoSe2 in the basal planes, and the P atoms enable Mo and Co atoms adjacent to them become the most active ones, according to Density Functional Theory calculations. Our work, using two layered materials as precursors to intercalate with each other, provides new ideas for designing efficient and non-precious metal electrocatalysts. Moreover, this method can be universally applicable to synthesize other hybrid materials such as CoSe2/MoSe2, FeP/MoSe2, NiP/MoSe2, CoSe2/WS2, FeP/TiS2 and so on.  相似文献   

19.
Hydrogen has concerned interest universally as an environmentally nontoxic and renewable fuel. Electrocatalytic hydrogen evolution reaction (HER) is one of the utmost favorable methods for hydrogen creation on a vast scale; however, the high cost of Pt-based supplies, which demonstrate the highest activity for HER, forced investigators to look for cheaper electro-catalysts. Tungsten has been considered as an effective, active and low cost electrocatalyst for the hydrogen evolution reaction, mostly in alkaline media, and we have investigated here its behavior in acid electrolytes. HER has been studied utilizing linear polarization technique and electrochemical impedance spectroscopy (EIS). It happens on W at rather low overpotential (−0.32 V vs. NHE at 10 mA cm−2, in 0.5 M H2SO4), yet more cathodic than the widely used Pt/C catalyst, but not so far from more sophisticated systems developed recently. The effect of acid concentration on the HER rate and the electrode stability was investigated. Cathodic transfer coefficient and exchange current density were calculated for the HER from Tafel curves obtained in H2SO4 solution at concentrations ranging from 0.1 to 3.0 M. EIS experiments were performed under both open circuit and/or cathodic polarization. It was found that the hydrogen evolution rate is relatively high under low overpotential, confirming that W is a possible applicant to substitute more expensive electrocatalysts usually used for the HER under acidic conditions. The process is economic and appropriate with no need for specific treatments, as supported by additional X-ray diffraction (XRD), Atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) characterization of the tungsten electrode surface.  相似文献   

20.
Evidence shows that embedding metal-based hybrid into carbon matrix is an up-and-coming method to improve the efficiency and decrease the cost of electrocatalysts. Herein, by using a metal-organic framework (MOF) with 4,4-bipyridine and 2,5-thiophenedicarboxylic acid as a precursor, a CoP/Co3S4 hybrid embedded into N, S, O-doped carbon sheets (CoP/Co3S4@NSOC) was constructed through pyrolysis and phosphorization processes. The lamellar morphology, hetero-atom doping, and graphite carbon were favorable for fast electron and mass transfer. Moreover, the strong intrinsic activities of CoP and Co3S4 promoted electrocatalytic performance. In the electrochemical experiments, CoP/Co3S4@NSOC showed the lowest overpotential of 132 mV@10 mA cm?2 for hydrogen evolution reaction (HER) among all the precursors. In addition, the electrocatalytic activity and structure of CoP/Co3S4@NSOC exhibited long-term stability over 60 h. The present work provides a feasible strategy for the construction of robust MOF-derived electrocatalysts.  相似文献   

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