01
2018
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03
Multi-stage structure high activity electrolysis water electrode
Author:
With the rapid consumption of fossil fuels and environmental pollution becoming more and more serious, the development of renewable energy is imperative. Hydrogen energy is considered to be expected to replace
With the rapid consumption of fossil fuels and environmental pollution becoming more and more serious, the development of renewable energy is imperative. Hydrogen energy is considered to be expected to replace traditional fossil fuels because of its clean and renewable characteristics. The key to deep utilization of hydrogen energy lies in the low-cost, large-scale production of hydrogen. Hydrogen production by electrolysis of water is one of the effective ways, but its anode oxygen evolution reaction (OER) and cathode hydrogen evolution reaction (HER) still show a high overpotential, which greatly limits the efficiency of hydrogen production by electrolysis of water. So far, precious metal materials Pt/C and IrO2 are highly efficient catalysts for HER and OER, respectively, but their high price and limited storage capacity limit their large-scale applications. Although a series of advances have been made in the research of non-precious metal HER and OER catalysts, there are still some challenges. For example, how to prepare high-activity multi-level nanostructured electrodes easily and on a large scale to realize full-water electrolysis under high current density is still one of the urgent problems and challenges to be solved.
Recently, the research group of Researcher Hu Jinsong from the Institute of Chemistry of the Chinese Academy of Sciences and Professor Li Jihui of Hebei Normal University reported a simple chemical etching method in which industrial NiAl alloys are immersed in a strong alkali solution. Because the metal Al is easily etched by the strong alkali At the same time, the metal Ni easily reacts with the strong alkali, thereby directly generating the Ni(OH)2 nanosheet array on the NiAl alloy substrate, forming a highly porous hierarchical structure Ni(OH)2/NiAl. Electrochemical studies show that the framework exhibits good OER catalyst performance, and the overpotentials at current densities of 10 and 100 mA cm-2 are 289 and 425 mV, respectively. On this basis, the researchers used simple electrodeposition methods to deposit NiMo alloys with higher activity for hydrogen evolution reactions and NiFe alloys with higher activity for oxygen evolution reactions on the Ni(OH)2/NiAl active framework. Through the combination of active material and three-dimensional multi-stage active framework structure, more efficient hydrogen evolution electrode NiMo/Ni(OH)2/NiAl and oxygen evolution electrode NiFe/Ni(OH)2/NiAl are obtained. The overpotential of the obtained composite hydrogen evolution electrode at 10 mA cm-2 is only 78 mV; and the overpotential of the composite oxygen evolution electrode at current densities of 10, 100 and 500 mA cm-2 is only 246, 315 and 374 mV, respectively . The cell pressure of the water electrolysis device composed of these two electrodes under alkaline conditions is only 1.59 V at a current density of 10 mA cm-2.
Since the preparation method of the electrolyzed water electrode in this research work is extremely simple and the raw materials are readily available, high-efficiency water electrolysis can be achieved by directly immersing the industrial NiAl alloy in the alkaline electrolyte. At the same time, the design of the multi-stage electrode structure is beneficial to realize the The electrolyzed water under the current density is very convenient for large-scale preparation and practical industrial application, and it is expected to realize large-scale production and application. This method of preparing electrochemical device electrodes with multi-level nanostructures by etching industrial alloys also provides new ideas for the design of other highly active electrodes.
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