The Controllable Synthesis Of Mo₂C And Its Electrocatalytic Performance For Hydrogen Evolution

Since the beginning of the 21st century,the global economy has been accompanied by a rapid increase in the level of science and technology.The living standards of human beings are constantly improving.However,environmental problems such as global warming,land desertification,and resource depletion have followed.Sustainable development has become the basic strategic approach of many countries,and clean energy has become the main solution to global warming and other environmental problems.Hydrogen(H2)is a good energy that can be stored,and the product water and hydrogen after combustion are non-toxic and will not cause pollution.These environmentally friendly features that make it an ideal alternative to other fuels.Hydrolysis by hydrogen evolution reaction is a common method of hydrogen production.Hydrogen evolution catalysts have a very important effect on the efficiency of the preparation process.Different catalysts will affect the speed and yield of the reaction.Considering energy conservation,lower overpotential and Excellent stability is recognized as a necessary factor for electrocatalysts,and platinum electrocatalysts are widely recognized as the standard for related electrocatalysts because of their better performance.Transition metals are often used in the preparation of hydrogen evolution catalysts,because the outer electron orbits similarity to precious metals.Among them,molybdenum is often used to replace precious metal catalysts such as platinum due to its low cost and large storage capacity.As one of the molybdenum-based compounds,molybdenum carbide has good electrocatalytic performance.However,molybdenum carbide will reduce the reactivity due to the characteristics of easy polymerization and excessive growth during the calcination molding process.Researchers have done a lot of research for this problem.Changing the microstructure and modifying other transition metals can effectively improve the electrochemical hydrogen evolution reaction activity of Mo2C.We did the following work focusing on electrochemical performance of molybdenum carbide:(1)Oxalic acid and melamine were used as carbon sources.And ammonium heptamolybdate was used as the molybdenum source.With simple stirring,the two-step method is calcined.Carbon-nitrogen-doped molybdenum carbide(Mo2C@CN)was prepared.Since oxalic acid generates carbon dioxide during the heating process,a porous structure is produced after the sample formed.This microstructure increases the specific surface area of the catalyst and speeds up the electrochemical reaction process.In subsequent electrocatalytic experiments.In an acidic environment,the overpotential required to reach a current density of 10 mA/cm2 was 202 mV.It is shown that the nitrogen-doped molybdenum carbide with layered me soporous structure has much better hydrogen evolution catalytic performance than ordinary molybdenum carbide.And using oxalic acid as a carbon source effectively solves the problem of excessive growth during calcination.(2)Urea was used as the carbon source,and ammonium heptamolybdate was used as the molybdenum source.Molybdenum carbide related catalysts were prepared by a method of high temperature heating after mixing and stirring.The corresponding overpotential of the catalyst in a 1 M KOH solution at a current density of 10 mA/cm2 was 157 mV.Compared with Experiment 1,it not only improves the hydrogen evolution performance,but also shortens the experiment cycle.Figure[24]table[3]reference[104]...