Interfacial Modulation Of Transition Metal Nitride Based Heterojunctions For Hydrogen Electrocatalysts In Alkaline Solution

Hydrogen,as a new renewable energy source with no pollution and high energy density,is expected to play an important role in the implementation of carbon neutral strategies.Among various routes to hydrogen generation,electrocatalytic water-splitting is favored by researchers due to the non-adverse sub-products and the high purity of H2 during production.Currently,the rate of hydrogen evolution reactions exist with variations at different pH values.Compared to acidic environments,hydrogen evolution reactions in alkaline solutions exhibit a slower reaction kinetics,which greatly affects the large-scale application of hydrogen production by water electrolysis in alkaline environments.Therefore,it is urgent to develop low-cost and high-efficiency electrocatalysts for alkaline hydrogen evolution.The adoption of heterostructure catalysts is an effective solution to the challenge of hydrogen evolution reactions in alkaline environments.Heterostructure catalysts can provide different active sites to facilitate the two reaction processes of H adsorption and water dissociation respectively.However,heterostructure catalysts for alkaline hydrogen evolution reaction present the following problems:1)For heterostructure catalysts that consist of noble metals,how to further decrease the consumption of noble metals without sacrificing the catalytic performance?2)For non-precious metal heterostructure,how to accurately regulate the electronic structure of the diverse components to attain a dramatic increase in catalytic performance?Resolving such questions is crucial for realizing the industrial application of heterostructure alkaline catalysts.To address the above questions,this thesis constructs heterostructure catalysts on the basis of transition metal nitrides and optimizes the performance of alkaline hydrogen evolution reaction through interfacial modulation.The specific work is as follows.（1）Based on the preparation of Pt nanocluster-modified Ni3N heterostructure catalysts,we further accelerate the water dissociation step in the reaction by modulating the adsorption energy of the Ni sites to H2O through Cr doping.Thus,the catalysts exhibited excellent alkaline HER catalytic performance,requiring an overpotential of only 20 mV to achieve a current density of 10 mA/cm2 in KOH.（2）We prepared CeO2/Co4N heterostructure catalysts for hydrogen evolution reaction in alkaline environments.Further,Ar/H2 plasma treatment was utilized to create abundant anionic vacancies at the heterointerface（p-CeO2/Co4N）.The experimental results show that the plasma treatment is capable of regulating the type and concentration of vacancies.Wherein,the introduction of O vacancies can enhance the adsorption of CeO2 on H2O,while N vacancies can enhance the adsorption of H on Co sites.This vacancy modulation significantly enhanced the alkaline HER performance of the heterostructure.Its HER overpotential in 1 M KOH solution is 36 mV@10 mA/cm2,which becomes one of the best non-precious metal catalysts with the best reported performance.