scholarly journals Synergistic Interfacial and Doping Engineering of Heterostructured NiCo(OH)x-CoyW as an Efficient Alkaline Hydrogen Evolution Electrocatalyst

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Ruopeng Li ◽  
Hao Xu ◽  
Peixia Yang ◽  
Dan Wang ◽  
Yun Li ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
High Efficiency ◽  
Low Voltage ◽  
Electrochemical Etching ◽  
Synergistic Effects ◽  
Release Kinetics ◽  
Water Electrolysis ◽  
Water Dissociation ◽  
Practical Applications ◽  
Environmentally Friendly Process

AbstractTo achieve high efficiency of water electrolysis to produce hydrogen (H2), developing non-noble metal-based catalysts with considerable performance have been considered as a crucial strategy, which is correlated with both the interphase properties and multi-metal synergistic effects. Herein, as a proof of concept, a delicate NiCo(OH)x-CoyW catalyst with a bush-like heterostructure was realized via gas-template-assisted electrodeposition, followed by an electrochemical etching-growth process, which ensured a high active area and fast gas release kinetics for a superior hydrogen evolution reaction, with an overpotential of 21 and 139 mV at 10 and 500 mA cm−2, respectively. Physical and electrochemical analyses demonstrated that the synergistic effect of the NiCo(OH)x/CoyW heterogeneous interface resulted in favorable electron redistribution and faster electron transfer efficiency. The amorphous NiCo(OH)x strengthened the water dissociation step, and metal phase of CoW provided sufficient sites for moderate H immediate adsorption/H2 desorption. In addition, NiCo(OH)x-CoyW exhibited desirable urea oxidation reaction activity for matching H2 generation with a low voltage of 1.51 V at 50 mA cm−2. More importantly, the synthesis and testing of the NiCo(OH)x-CoyW catalyst in this study were all solar-powered, suggesting a promising environmentally friendly process for practical applications.

scholarly journals Electrochemically Induced In-Situ Generated Co(OH)2 Nanoplates to Promote the Volmer Process Toward Efficient Alkaline Hydrogen Evolution Reaction

2020 ◽  
Author(s):  
Hong Liu ◽  
Jian-Jun Wang ◽  
Li-Wen Jiang ◽  
Yuan Huang ◽  
Bing Bing Chen ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Active Sites ◽  
Water Electrolysis ◽  
Water Dissociation ◽  
Alkaline Water Electrolysis ◽  
Additional Water ◽  
Dissociation Step ◽  
Insight Into

<p>Hydrogen production via alkaline water electrolysis is of significant interest. However, the additional water dissociation step makes the Volmer step a relatively more sluggish kinetics and consequently leads to a slower reaction rate than that in acidic solution. Herein, we demonstrate an effective strategy that Co(OH)<sub>2</sub> can promote the Volmer process by accelerating water dissociation and enhance the electrocatalytic performance of CoP toward alkaline hydrogen evolution reaction. The Co(OH)<sub>2</sub> nanoplates are electrochemically induced in-situ generated to form a nanotree-like structure with porous CoP nanowires, endowing the hybrid electrocatalyst with superior charge transportation, more exposed active sites, and enhanced reaction kinetics. This strategy may be extended to <a></a><a>other phosphides and chalcogenides </a>and provide insight into the design and fabrication of efficient alkaline HER catalysts.</p>

scholarly journals Electrochemically Induced In-Situ Generated Co(OH)2 Nanoplates to Promote the Volmer Process Toward Efficient Alkaline Hydrogen Evolution Reaction

2020 ◽  
Author(s):  
Hong Liu ◽  
Jian-Jun Wang ◽  
Li-Wen Jiang ◽  
Yuan Huang ◽  
Bing Bing Chen ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Active Sites ◽  
Water Electrolysis ◽  
Water Dissociation ◽  
Alkaline Water Electrolysis ◽  
Additional Water ◽  
Dissociation Step ◽  
Insight Into

<p>Hydrogen production via alkaline water electrolysis is of significant interest. However, the additional water dissociation step makes the Volmer step a relatively more sluggish kinetics and consequently leads to a slower reaction rate than that in acidic solution. Herein, we demonstrate an effective strategy that Co(OH)<sub>2</sub> can promote the Volmer process by accelerating water dissociation and enhance the electrocatalytic performance of CoP toward alkaline hydrogen evolution reaction. The Co(OH)<sub>2</sub> nanoplates are electrochemically induced in-situ generated to form a nanotree-like structure with porous CoP nanowires, endowing the hybrid electrocatalyst with superior charge transportation, more exposed active sites, and enhanced reaction kinetics. This strategy may be extended to <a></a><a>other phosphides and chalcogenides </a>and provide insight into the design and fabrication of efficient alkaline HER catalysts.</p>

Synergistically enhanced hydrogen evolution electrocatalysis by in situ exsolution of metallic nanoparticles on perovskites

2018 ◽  
Vol 6 (28) ◽  
pp. 13582-13587 ◽  
Author(s):  
Yinlong Zhu ◽  
Jie Dai ◽  
Wei Zhou ◽  
Yijun Zhong ◽  
Huanting Wang ◽  
...  
Keyword(s):  
Metal Nanoparticles ◽  
Hydrogen Evolution ◽  
Metallic Nanoparticles ◽  
High Efficiency ◽  
Hydrogen Adsorption ◽  
Water Dissociation

The metal nanoparticles (NPs)/perovskite hybrid prepared by in situ exsolution can synergistically catalyze the alkaline HER with high efficiency whereby the perovskite promotes water dissociation and metal NPs enable favorable hydrogen adsorption.

scholarly journals 2D CoOOH Sheet-Encapsulated Ni2P into Tubular Arrays Realizing 1000 mA cm−2-Level-Current-Density Hydrogen Evolution Over 100 h in Neutral Water

2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Shucong Zhang ◽  
Wenbin Wang ◽  
Feilong Hu ◽  
Yan Mi ◽  
Shuzhe Wang ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Current Density ◽  
High Efficiency ◽  
Mechanical Stability ◽  
High Current Density ◽  
Water Electrolysis ◽  
Intrinsic Activity ◽  
High Current ◽  
Neutral Water ◽  
Tubular Arrays

AbstractWater electrolysis at high current density (1000 mA cm−2 level) with excellent durability especially in neutral electrolyte is the pivotal issue for green hydrogen from experiment to industrialization. In addition to the high intrinsic activity determined by the electronic structure, electrocatalysts are also required to be capable of fast mass transfer (electrolyte recharge and bubble overflow) and high mechanical stability. Herein, the 2D CoOOH sheet-encapsulated Ni2P into tubular arrays electrocatalytic system was proposed and realized 1000 mA cm−2-level-current-density hydrogen evolution over 100 h in neutral water. In designed catalysts, 2D stack structure as an adaptive material can buffer the shock of electrolyte convection, hydrogen bubble rupture, and evolution through the release of stress, which insure the long cycle stability. Meanwhile, the rich porosity between stacked units contributed the good infiltration of electrolyte and slippage of hydrogen bubbles, guaranteeing electrolyte fast recharge and bubble evolution at the high-current catalysis. Beyond that, the electron structure modulation induced by interfacial charge transfer is also beneficial to enhance the intrinsic activity. Profoundly, the multiscale coordinated regulation will provide a guide to design high-efficiency industrial electrocatalysts.

scholarly journals Arrayed Cobalt Phosphide Electrocatalyst Achieves Low Energy Consumption and Persistent H2 Liberation from Anodic Chemical Conversion

2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Kai Zhang ◽  
Gong Zhang ◽  
Qinghua Ji ◽  
Jiuhui Qu ◽  
Huijuan Liu
Keyword(s):  
Energy Consumption ◽  
High Efficiency ◽  
Hydrogen Adsorption ◽  
Water Electrolysis ◽  
Clean Energy ◽  
Chemical Conversion ◽  
Water Dissociation ◽  
Hydrogen Purification ◽  
Alkaline Water Electrolysis ◽  
Cobalt Phosphide

AbstractElectrochemical reduction of water to hydrogen (H2) offers a promising strategy for production of clean energy, but the design and optimization of electrochemical apparatus present challenges in terms of H2 recovery and energy consumption. Using cobalt phosphide nanoarrays (Co2P/CoP NAs) as a charge mediator, we effectively separated the H2 and O2 evolution of alkaline water electrolysis in time, thereby achieving a membrane-free pathway for H2 purification. The hierarchical array structure and synergistic optimization of the electronic configuration of metallic Co2P and metalloid CoP make the Co2P/CoP NAs high-efficiency bifunctional electrocatalysts for both charge storage and hydrogen evolution. Theoretical investigations revealed that the introduction of Co2P into CoP leads to a moderate hydrogen adsorption free energy and low water dissociation barrier, which are beneficial for boosting HER activity. Meanwhile, Co2P/CoP NAs with high capacitance could maintain a cathodic H2 evolution time of 1500 s at 10 mA cm−2 driven by a low average voltage of 1.38 V. Alternatively, the energy stored in the mediator could be exhausted via coupling with the anodic oxidation of ammonia, whereby only 0.21 V was required to hold the current for 1188 s. This membrane-free architecture demonstrates the potential for developing hydrogen purification technology at low cost.

Hierarchical FeCo2S4@CoFe layered double hydroxide on Ni foam as a bifunctional electrocatalyst for overall water splitting

2020 ◽  
Vol 10 (5) ◽  
pp. 1292-1298 ◽  
Author(s):  
Yunxia Huang ◽  
Xiaojuan Chen ◽  
Shuaipeng Ge ◽  
Qiqi Zhang ◽  
Xinran Zhang ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Water Splitting ◽  
Hydrogen Evolution Reaction ◽  
Oxygen Evolution Reaction ◽  
High Efficiency ◽  
Low Cost ◽  
Water Electrolysis ◽  
Ni Foam ◽  
Bifunctional Electrocatalyst ◽  
Double Hydroxide

Designing high-efficiency and low-cost bifunctional electrocatalysts for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is of great significance to produce hydrogen by water electrolysis.

Engineering of Ru/Ru2P interfaces superior to Pt active sites for catalysis of the alkaline hydrogen evolution reaction

2019 ◽  
Vol 7 (10) ◽  
pp. 5621-5625 ◽  
Author(s):  
Zhao Liu ◽  
Zhe Li ◽  
Jing Li ◽  
Jie Xiong ◽  
Shunfa Zhou ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Active Sites ◽  
Synergistic Effects ◽  
Water Dissociation ◽  
Proton Reduction ◽  
Mass Activity

Based on the synergistic effects of Ru on water dissociation and Ru2P on proton reduction, Ru/Ru2P interfaces were engineered in situ, and the mass activity of the new catalyst for the alkaline HER was doubled compared to Pt/C.

Self-supported hierarchical nanoporous Cu/Mo@MoOx hybrid electrodes as robust nonprecious electrocatalysts for high-efficiency hydrogen evolution

2021 ◽  
Vol 16 ◽  
Author(s):  
Li-Ping Han ◽  
Hang Shi ◽  
Rui-Qi Yao ◽  
Wu-Bin Wan ◽  
Zi Wen ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Large Scale ◽  
High Efficiency ◽  
Alkaline Media ◽  
Water Dissociation ◽  
Transport Pathways ◽  
Highly Active ◽  
Additional Water ◽  
Electrochemical Water Splitting ◽  
Spontaneous Phase

Background: The hydrogen evolution reaction is a crucial step in electrochemical water splitting to generate molecular hydrogen with high purity, but it usually suffers from a sluggish reaction kinetics in alkaline media because of additional water dissociation and/or improper adsorption energy of reactive hydrogen intermediates. It is desirable to design highly active and robust nonprecious electrocatalysts as alternatives to state-of-the-art commercially available Pt/C catalyst for large-scale hydrogen production via water-alkali electrolysis. Methods: We develop monolithic nanoporous hybrid electrodes composed of electroactive Mo@MoOx nanoparticles, which are seamlessly integrated on hierarchical nanoporous Cu scaffold (Cu/Mo@MoOx) by making use of a spontaneous phase separation of Mo nanoparticles and subsequently self-grown MoOx in chemical dealloying. Results: Owing to the unique monolithic electrode architecture, in which the constituent Mo@MoOx nanoparticles work as electroactive sites and the hierarchical nanoporous Cu skeleton serves as fast electron-transfer and mass-transport pathways, the monolithic nanoporous Cu/Mo@MoOx hybrid electrode exhibits a superior electrocatalysis in 1 M KOH, with a low Tafel slope of 66 mV dec-1 and outstanding stability. It only takes them ~185 mV overpotential to reach -400 mA cm-2 , ~150 mV lower than that of nanoporous Cu supported Pt/C. Conclusion: The outstanding electrochemical performance and excellent structural stability make nanoporous Cu/Mo@MoOx electrodes attractive alternatives to Pt/C catalysts in alkaline-based devices.

scholarly journals Evaluation of A-Site Ba2+-Deficient Ba1−xCo0.4Fe0.4Zr0.1Y0.1O3−δ Oxides as Electrocatalysts for Efficient Hydrogen Evolution Reaction

Scanning ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Xiangnan Li ◽  
Liqing He ◽  
Xiongwei Zhong ◽  
Jie Zhang ◽  
Shijing Luo ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Oxygen Vacancies ◽  
Water Electrolysis ◽  
Cost Effective ◽  
Alkaline Water Electrolysis ◽  
Practical Applications ◽  
Earth Abundant ◽  
A Site

Exploring earth-abundant and cost-effective catalysts with high activity and stability for a hydrogen evolution reaction (HER) is of great importance to practical applications of alkaline water electrolysis. Here, we report on A-site Ba2+-deficiency doping as an effective strategy to enhance the electrochemical activity of BaCo0.4Fe0.4Zr0.1Y0.1O3−δ for HER, which is related to the formation of oxygen vacancies around active Co/Fe ions. By comparison with the benchmarking Ba0.5Sr0.5Co0.8Fe0.2O3−δ, one of the most spotlighted perovskite oxides, the Ba0.95Co0.4Fe0.4Zr0.1Y0.1O3−δ oxide has lower overpotential and smaller Tafel slope. Furthermore, the Ba0.95Co0.4Fe0.4Zr0.1Y0.1O3−δ catalyst is ultrastable in an alkaline solution. The enhanced HER performance originated from the increased active atoms adjacent to oxygen vacancies on the surface of the Ba0.95Co0.4Fe0.4Zr0.1Y0.1O3−δ catalyst induced by Ba2+-deficiency doping. The low-coordinated active atoms and adjacent oxygen ions may play the role of heterojunctions that synergistically facilitate the Volmer process and thus render stimulated HER catalytic activity. The preliminary results suggest that Ba2+-deficiency doping is a feasible method to tailor the physical and electrochemical properties of perovskite, and that Ba0.95Co0.4Fe0.4Zr0.1Y0.1O3−δ is a potential catalyst for HER.

Synthesis and Electrochemical Properties of NiFe-Se/rGO Nanocomposites

2020 ◽  
Vol 13 ◽  
Author(s):  
Rouwei Yan ◽  
Biao Xu ◽  
K. P. Annamalai ◽  
Tianlu Chen ◽  
Zhiming Nie ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Graphene Oxide ◽  
Energy Storage ◽  
Synergistic Effects ◽  
Nitrogen Adsorption ◽  
Storage Device ◽  
Energy Storage And Conversion ◽  
Step Method ◽  
Practical Applications ◽  
Device Applications

Background : Renewable energies are in great demand because of the shortage of traditional fossil energy and the associated environmental problems. Ni and Se-based materials are recently studied for energy storage and conversion owing to their reasonable conductivities and enriched redox activities as well as abundance. However, their electrochemical performance is still unsatisfactory for practical applications. Objective: To enhance the capacitance storage of Ni-Se materials via modification of their physiochemical properties with Fe. Methods: A two-step method was carried out to prepare FeNi-Se loaded reduced graphene oxide (FeNi-Se/rGO). In the first step, metal salts and graphene oxide (GO) were mixed under basic condition and autoclaved to obtain hydroxide intermediates. As a second step, selenization process was carried out to acquire FeNi-Se/rGO composites. Results: X-ray diffraction measurements (XRD), nitrogen adsorption at 77K, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were carried out to study the structures, porosities and the morphologies of the composites. Electrochemical measurements revealed that FeNi-Se/rGO notably enhanced capacitance than the NiSe/G composite. This enhanced performance was mainly attributed to the positive synergistic effects of Fe and Ni in the composites, which not only had influence on the conductivity of the composite but also enhanced redox reactions at different current densities. Conclusion: NiFe-Se/rGO nanocomposites were synthesized in a facile way. The samples were characterized physicochemically and electrochemically. NiFeSe/rGO giving much higher capacitance storage than the NiSe/rGO explained that the nanocomposites could be an electrode material for energy storage device applications.

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