Preparation Of Transition Metal Oxide/Sulfide Material And OER Electrochemical Properties

Environmental pollution and energy shortage caused by the combustion of traditional fossil fuels have attracted extensive attention all over the world.Hydrogen energy is considered to be an ideal alternative energy to fundamentally solve global problems such as energy and environment because of its high energy density,sustainability,clean and non-pollution and low molecular weight.Electrolyzed water is an important method for producing high-purity hydrogen and an important component of modern clean energy technology.At present,RuO₂ and IrO₂ noble metal catalysts used in electrocatalytic hydrogen production are effective but expensive,and the element reserves are limited.Oxygen evolution reaction?OER?involves several proton coupled electron transfer steps,and the kinetics is slow,which has been a difficult problem in the field of hydrogen production from electrolytic water.In order to improve the energy conversion efficiency of hydrogen production from electrolytic water,it is worth paying attention to find a new efficient and stable OER electrocatalyst.In this thesis,Ce-doped MnO2 nano-flowers,Ce-doped CuS nanosheets and W-doped CuS micron-flower structures were synthesized.The preparation of transition metal oxygen/sulfide catalytic materials and their oxygen evolution properties were studied as follows:1.A series of rare earth element Ce doped?-MnO2 nano-flowers are prepared by simple hydrothermal method for redox reaction method and applied for catalytic Oxygen evolution reaction.The results show that when cerium is 0.0250 mmoL,Ce-MnO₂ exposes a larger specific surface area.Delivering a current density of 10 mA cm^-22 with an overpotential merely of 221 mV and a Tafel slope of 44 m V dec^-11 in 1.0 M KOH,which shows excellent electrocatalytic activity for oxygen evolution reaction?OER?.Due to the regulation of doping effect and rich defects,this viable synthetic strategy will open a new way for cheap and efficient electrocatalysts of non-precious metals,displaying superior oxygen evolution reaction?OER?electrocatalytic activity.2.CuS nanotubes have been successfully synthesized via a facile solvothermal method of redox reaction,the electronic structure was adjusted by rare earth element Ce doping in OER reaction.The optimal 0.05 mmoL Ce droped in CuS OER catalyst reaches a Tafel slope of 172.56 mV dec^-11 and an overpotential of 320 m V at a current density of 50mA cm^-2.There is a strong synergistic effect between the addition of Ce and CuS regulates the surface chemical states so as to enrich structural defects,further exposing more active sites and accelerating the transport of electrolytes.3.Tungsten-doped CuS micron-flower materials were prepared by a simple one-step hydrothermal method for Oxygen evolution reaction?OER?catalysts.The results show that the W content is 0.10 mmoL,W-doped CuS reaching 50 mA cm-2 at an overpotential of 277 mV and a Tafel slope of 172.56 mV dec^-1,which shows excellent electrocatalytic activity and good durability.The three-dimensional micron-flower structure increases the contact between the catalyst and the electrolyte and exposes more catalytic active sites.Therefore,doping Tungsten will be a promising approach to improve the OER activity of non precious metal catalysts.