Hydrogen Evolution Catalyst Derived From Two-dimensional Transition Metal Oxide

Hydrogen energy is the main component of the new energy system,and it is also an important connection hub for the new energy system and the green transportation system.Therefore,it has been highly valued by governments of various countries.As a new energy system that is likely to replace the petrochemical economy in the future,the hydrogen energy economy also has very good application prospects.The hydrogen energy economy mainly includes four aspects:hydrogen production,storage,transportation,and utilization.The first step is how to efficiently and cleanly produce hydrogen.Obviously,electrolysis of water to produce hydrogen has become a very effective way.Although platinum is still the first choice for electrocatalysts used in electrolytic cells due to its excellent activity and high current density,the high cost and scarcity of platinum has become a bottleneck in the development of electrolytic cells.Therefore,on the premise of ensuring the performance of the electrocatalyst,reducing the amount of platinum or developing a non-platinized HER catalyst has become an urgent task.The 2D transition metal oxides have the characteristics of large specific surface area,atomic level thickness and abundant suspended bonds,which provide the conditions for the 2D transition metal oxides to have excellent catalytic,photovoltaic and electrochemical properties.Based on this,in this paper,the noble metal Ru was doped into 2D transition metal oxide nanosheets.By changing a series of synthesis conditions,such as reduction temperature,reduction time,hydrogen nitrogen ratio,Ru content and so on,different catalyst materials were finally prepared,and their physical characterization and electrochemical performance were tested.The main work is as follows:1.Preparation and research of Ru-WO_X（0<x<3）catalystFirst,the WO₃ powder was synthesized by a simple and controllable hydrothermal method,and then powdered WO₃,RuCl₃ solution and H₂O were mixed according to a certain ratio.After a series of treatments such as stirring for 24 h,oven drying,tube furnace hydrogen reduction,different ratios Ru-WO_X（0<x<3）catalyst materials were prepared.The obtained samples were subjected to XRD,SEM,TEM,XPS and other physical characterization and HER electrochemical tests.The catalyst composition,morphology and HER performance obtained under different conditions were thoroughly investigated,compared and evaluated.It can be concluded that when the content of Ru is3%,the reduction time is 2 h,the reduction temperature is 550℃,H₂:N₂=1:4,the prepared catalyst material is a mixture of WO_2.9 and W.When the density is 10 mA cm^-2,only 10 mV of overpotential is required.At the same precious metal content,the HER overpotential shifted to the right by 59 mV compared to Pt/C.Electrochemical tests indicate that this catalyst has the largest electrochemical surface area,the largest exchange current density,the smallest Tafel slope,and the lowest charge transfer resistance.This is mainly due to the high-temperature W-based oxide crystal transformation,which is crucial to the hydrogen evolution activity of the catalyst.The metal Ru content,annealing temperature,and time are the main factors controlling the crystal transformation.2.Preparation and Research of Ru-TiO₂ CatalystIn order to further explore the influence of the precious metal Ru on the HER performance of other transition metal oxides,Ru-TiO₂ was obtained by using p123,ethanol,isopropanol peptide,concentrated hydrochloric acid,ethylene glycol and other substances through hydrothermal and hydrogen reduction treatment Catalyst material.After that,the catalyst composition,morphology,and HER performance obtained under different conditions were thoroughly investigated,compared,and evaluated.It was concluded that Ru-TiO₂-900℃had the best HER activity when the current density was10 mA cm^-2,only 45 mv of overpotential is required.At the same precious metal content,the HER overpotential shifted to the right by 24 mV compared to Pt/C.