The Design、Preparation And Properties Of Electrocatalysts Towards Hydrogen Evolution Reaction

With the global economic development,gradual depletion of fossil fuels and the burning of fossil fuels create air pollution and other environmental problems,forcing people to the urgent need to find one or more clean,renewable new energy sources.New energy sources,including solar,wind,biomass and hydrogen energy.In these new energy sources,because of the rich source from nature,clean,generating more energy and high energy efficiency,hydrogen energy has attracted more and more attention.Electrolysis of water is one of the easiest way to produce hydrogen.While,the realization of the hydrogen evolution reaction（HER）often requires high overpotential and it’s difficult to carry out at low overpotential.Therefore,it needs to find a catalyst to efficient electrocatalyst water at a low HER overpotential.At present,the platinum group metals are the best HER electrochemical catalysts.While,rare and expensive,making it difficult to obtain a large^-scale application promotion.So,looking for cheap and rich HER catalysts has attracted many more researchers working on these.In these catalysts that have been found,the molybdenum compounds have made notable achievements in the past few years,including molybdenum disulfide,molybdenum selenide,molybdenum carbide,boron nitride,molybdenum and molybdenum and so on.The transition metal phosphide has also attract a great concern on the HER catalysts.So,it’s a hot topic to develop clean renewable energy and looking for efficient catalysts for hydrogen evolution is imperative.A complete water splitting process can be divided into two half reactions: water oxidation（1）and hydrogen evolution（2）2H₂O→O₂+2H₂（Total reaction）2H₂O →O₂+4H⁺+4e^-（1）4H⁺+4e^-→2H₂（2）Many water-splitting processes often depend on the final step,which is hydrogen evolution.The first step of hydrogen evolution is a combination of hydrogen ions and electrons,that is H⁺ + e^-+*→H*.* represents the binding site on the surface of hydrogen.The second step is the release of hydrogen molecules through one or two process,that is 2H* → H₂ + 2* or H⁺ + e^-+ H* → H₂ + *.So the study of hydrogen evolution has great significance in the development of hydrogen energy.Molybdenum disulfide,a typical of layered minerals in nature,often proved to be the catalyst for hydrodesulfurization reaction in recent years.In recent years,it becomes a "star molecule" in hydrogen evolution reaction.It is proved by calculation and experimental results that the effieciency of hydrogen evolution depends on the disulfide edge of molybdenum disulfide.While,its base is generally inert.Therefore,the nanoscale molybdenum disulfide has higher activity than bulk molybdenum disulfide towards the hydrogen evolution reaction.Carbon nanotubes,due to their chemical and mechanical properties,like unique electronic conductivity,biocompatibilityand easy functioned,often applied to various fields of nanoelectronics,catalysis,materials science and biology.They are used to supporte catalysts which are difficult to adhere to the electrodes,greatly improving the catalytic conductivity and the effiency.Mulberry,belonging to the family Moraceae,a traditional herbal medicine and growing well all over the year.Mulberry has been found to have potent antioxidant activity,antitumor activity,hypolipidemic effect and neuroprotective activity.Indeed,it’s also a carbon material after being burned and carbon material performs good catalytic activity after electrochemical treatment.Thus,it has promising prospect in the use of energy.In this paper,we combine the "star elements" molybdenum disulfide with a new carbon material-amino-functionalized carbon nanotubes as an electrode material to construct the relevant electrochemical catalyst for hydrogen energy.The specific detailes were summarized as follows:1.Study the catalytic performance of molybdenum disulfide directly on the amino-functionalized carbon nanotubes towards hydrogen evolution reduction.2.Prepare the mulberry leaves product through vacuum burning and after electrochemical treatment in acid solutions,exploring its electrocatalytic behavior towards hydrogen evolution reduction.Based on this,the catalyst shows the onset potential of 50 mV,tafel slope of 96 mV / dec and the overpotential are 275 mV and 321 mV at a current density of 10 and 20 m A cm^-2,only take a potential,in acidic solution in four hours electrochemical process can maintain its good catalytic activity.3.Based on the carbon nanotube material,including single^-walled carbon nanotubes,multi-walled carbon nanotubes and amino-functionalized carbon nanotubes.We prepare these nanotubes via electrochemical treatment and observe its initial potential and tafel curve,exploring their catalytic performance towards hydrogen evolution reaction.