Noble-Metal-Free Hybridized Materials In Hydrogen Evolution Reaction

Globally increasing energy demands and deteriorating environmental issues have stimulated extensive research to seek sustainable,cheap,clean,environmentally friendly new energy sources in order to reduce the dependent on fossil fuels.Among various alternative energy sources,hydrogen is not only a high calorific value,non-polluting energy source but also an optimal carrier for energy storage and transportation.Up to now,Water splitting for hydrogen generation is the main component of contemporary clean-energy technologies.However,Water splitting for hydrogen generation is a very difficult process in terms of Chemical reaction kinetics.Furthermore,it requires the use of precious metal catalysts such as platinum.However,the scarcity and high price of these precious metal catalysts have greatly limited their application in business on a large scale.Even so,platinum-based noble metal materials can still be replaced with non-precious metal nanomaterials(eg transition metal sulfides,transition metal phosphides,carbon-based non-metallic materials et al.).These non-precious metal materials are not only close to platinum-based catalysts in hydrogen evolution performance,but also rich in content and low in price.Therefore,these materials will become the main catalyst for the electrolysis of hydrogen in the future inevitably.This article is divided into the following three chapters.In chapter 1,it mainly introduces the general situation of electrolytic hydrogen production.The whole reaction process is understood from the reaction mechanism of water splitting for hydrogen generation,and then the influencing factors of hydrogen evolution in water splitting are analyzed by the main HER parameters such as overpotential,Tafel slope,exchange current density,electrochemical impedance and electrochemical activity area.At last,the efficiency and reaction process of hydrogen evolution under different pH conditions are introduced.In addition,the research progress of the hydrogen evolution reaction catalyst for water splitting is also introduced,and the research progress of transition metal compounds and non-metal complex catalysts is emphatically summarized.It can be concluded that research on non-precious metal catalysts has made great breakthroughs and these materials will replace precious metal catalysts,eventually.In chapter 2,the hydrogen evolution from the electrolysis of the black Phosphorous-molybdenum disulfide composite nanosheets was introduced.First,two-dimensional black Phosphorous nanosheets were synthesized,and these nanosheets were combined with molybdenum disulfide nanosheets through hydrothermal method.Through the use of a variety of characterization methods,it can be determined that a black phosphorus-molybdenum disulfide composite type-Ⅱheterojunction structure has been formed.Then,electrochemical tests were performed on this compound and it was found that the rate of hydrogen production was greatly improved over that of a single material.From the Mott Schottky curve,it can be concluded that the Fermi levels of the molybdenum disulfide and black Phosphorous nanosheets are in different positions,so that when the two materials are combined,a large amount of electrons will flow from the black Phosphorous to the molybdenum disulfide.As a result,the catalytic activity of molybdenum disulfide increases,the Gibbs free energy of the hydrogen evolution reaction decreases,and the reaction rate of the hydrogen evolution reaction in the electrolyzed water increases.In chapter 3,the main parts of this work have been summarized.The outlook for the application of non-noble metal electrochemical hydrogen evolution catalysts has been prospected,and elaborated the opportunities and challenges of the hydrogen evolution reaction in water splitting from aspects of materials design,catalysts construction,and electron flow of catalytic reactions in the future.