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.

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 Alkaline Water Electrolysis Powered by Renewable Energy: A Review

Processes ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 248 ◽  
Author(s):  
Jörn Brauns ◽  
Thomas Turek
Keyword(s):  
Renewable Energy ◽  
Carbon Dioxide Emissions ◽  
High Efficiency ◽  
Operation Time ◽  
Water Electrolysis ◽  
Process Conditions ◽  
Hydrogen Energy ◽  
Alkaline Water Electrolysis ◽  
Spinning Reserve ◽  
Alkaline Water

Alkaline water electrolysis is a key technology for large-scale hydrogen production powered by renewable energy. As conventional electrolyzers are designed for operation at fixed process conditions, the implementation of fluctuating and highly intermittent renewable energy is challenging. This contribution shows the recent state of system descriptions for alkaline water electrolysis and renewable energies, such as solar and wind power. Each component of a hydrogen energy system needs to be optimized to increase the operation time and system efficiency. Only in this way can hydrogen produced by electrolysis processes be competitive with the conventional path based on fossil energy sources. Conventional alkaline water electrolyzers show a limited part-load range due to an increased gas impurity at low power availability. As explosive mixtures of hydrogen and oxygen must be prevented, a safety shutdown is performed when reaching specific gas contamination. Furthermore, the cell voltage should be optimized to maintain a high efficiency. While photovoltaic panels can be directly coupled to alkaline water electrolyzers, wind turbines require suitable converters with additional losses. By combining alkaline water electrolysis with hydrogen storage tanks and fuel cells, power grid stabilization can be performed. As a consequence, the conventional spinning reserve can be reduced, which additionally lowers the carbon dioxide emissions.

scholarly journals Straight-Parallel Electrodes and Variable Gap for Hydrogen and Oxygen Evolution Reactions

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
María J. Lavorante ◽  
Carla Y. Reynoso ◽  
Juan I. Franco
Keyword(s):  
Energy Consumption ◽  
Electrical Resistance ◽  
Negative Electrode ◽  
Water Electrolysis ◽  
Alkaline Water Electrolysis ◽  
Stainless Steel 316L ◽  
Reduction Of Energy Consumption ◽  
The One ◽  
Definition Of ◽  
The Cost

The challenges to be overtaken with alkaline water electrolysis are the reduction of energy consumption, the maintenance, and the cost as well as the increase of durability, reliability, and safety. Having these challenges in mind, this work focused on the reduction of the electrical resistance of the electrolyte which directly affects energy consumption. According to the definition of electrical resistance of an object, the reduction of the space between electrodes could lower the electrical resistance but, in this process, the formation of bubbles could modify this affirmation. In this work, the performance analyses of nine different spaces between stainless steel 316L electrodes were carried out, although the spaces proposed are not the same as those from the positive electrode (anode) to the separator and from the separator to the negative electrode (cathode). The reason why this is studied is that stoichiometry of the reaction states that two moles of hydrogen and one mole of oxygen can be obtained per every two moles of water. The proposed spaces were 10.65, 9.20, 8.25, 7.25, 6.30, 6.05, 4.35, 4.15, and 3.40 millimetres. From the nine different analysed distances between electrodes, it can be said that the best performance was reached by one of the smallest distances proposed, 4.15 mm. When the same distance between electrodes was compared (the same and different distance between electrodes and separator), the one that had almost twice the distance (negative compartment) presented an increase in current density of approximately 33% with respect to that where both distances (from electrodes to separator) are the same. That indicates that the stichometry of the electrolysis reaction influenced the performance.

scholarly journals Lignin-Assisted Water Electrolysis for Energy-Saving Hydrogen Production With Ti/PbO2 as the Anode

2021 ◽  
Vol 9 ◽  
Author(s):  
Jiayi Li ◽  
Wei Zhou ◽  
Yuming Huang ◽  
Jihui Gao
Keyword(s):  
Energy Consumption ◽  
Hydrogen Production ◽  
Electricity Consumption ◽  
Cell Voltage ◽  
Linear Sweep Voltammetry ◽  
Water Electrolysis ◽  
High Energy ◽  
Alkaline Water Electrolysis ◽  
Lignin Concentration ◽  
Slow Kinetics

Replacing the oxygen evolution reaction (OER), which is of high energy consumption and slow kinetics, with the more thermodynamically favorable reaction at the anode can reduce the electricity consumption for hydrogen production. Here we developed a lignin-assisted water electrolysis (LAWE) process by using Ti/PbO2 with high OER overpotential as the anode aimed at decreasing the energy consumption for hydrogen production. The influence of key operating parameters such as temperature and lignin concentration on hydrogen production was analyzed. Compared with alkaline water electrolysis (AWE), the anode potential can be decreased from 0.773 to 0.303 (V vs. Hg/HgO) at 10 mA/cm2 in LAWE, and the corresponding cell voltage can be reduced by 546 mV. With increasing the temperature and lignin concentration, current density and H2 production rate were efficiently promoted. Furthermore, the anode deactivation was investigated by analyzing the linear sweep voltammetry (LSV) and cyclic voltammetry (CV) tests. Results showed that the anode deactivation was affected by the temperature.

Chestnut-like copper cobalt phosphide catalyst for all-pH hydrogen evolution reaction and alkaline water electrolysis

2019 ◽  
Vol 7 (23) ◽  
pp. 14271-14279 ◽  
Author(s):  
Liang Yan ◽  
Bing Zhang ◽  
Junlu Zhu ◽  
Shanzhi Zhao ◽  
Yunyong Li ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Alkaline Solution ◽  
Water Electrolysis ◽  
Alkaline Water Electrolysis ◽  
Alkaline Water ◽  
Cobalt Phosphide ◽  
Ph Values

Novel chestnut-like CuxCo1−xP/CP exhibited excellent activities for the HER at all pH values and the OER in alkaline solution.

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