Structural Regulation And Electrochemical Performance Of Molybdenum Nitride-based Nanomaterials

The development of human beings can not go on without the use of energy fuels.However,global warming,environmental pollution and energy security are becoming more and more serious due to the excessive consumption of fossil fuels.Hydrogen(H₂)has drawn wide attention owing to its high weight energy density and zero pollution during energy conversion,and is expected to become a substitute for traditional fossil fuels.In order to make more efficient and secure use of other new energy sources,such as H₂,the development of advanced energy storage and conversion devices such as fuel cells,overall water splitting,lithium ion batteries and metal-air batteries are also of crucial importance.Therefore,to reduce the complexity and cost of electrochemical energy storage and conversion devices and to achieve energy-saving,efficient and sustainable development,we urgently need an efficient multifunctional electrocatalyst.Molybdenum nitride(MoN)shows wide applications in new energy field due to its corrosion resistance,low resistivity and electrocatalytic activity.Studies have shown that metal doping has a great influence on its electrochemical performance.Therefore,two kinds of molybdenum nitride-based materials were controllablely synthesized by the doping of Group VIII metals(cobalt and nickel).The electrochemical properties of the materials were systematically studied.The main research contents are as follows:(1)Porous Co-doped MoN microspheres were prepared by a solvothermal method followed by ammoniation treatment.Extended X-ray absorption fine structures prove that Co is going at the Mo position in MoN lattice to obtain a pure Co-MoN phase.Theoretical calculations show that after the Co doping,the electronic structure of Co-MoN is adjusted,the free energy of hydrogen adsorption is decreased,and the conductivity is increased,all of which are responsible for improving the electrochemical performance.Electrochemical tests show that the as-obtained Co-MoN catalyst exhibits high activity and good stability towards hydrogen evolution reaction(HER)and oxygen reduction reaction(ORR).Co as the active center of oxygen production reaction(OER),makes Co-MoN to be efficient towards OER performance.Therefore,Co-MoN exhibits excellent multifunctional features.Besides,an overall water splitting device and rechargeable Zn-Air battery with Co-MoN as the electrode were fabricated,realizing the Zn-Air battery self-driving diode light and the overall water splitting.(2)By using the solvothermal method,Ni-Mo precursor with uniform morphology was obtained and subsequent ammoniation treatment leads to the target product:Ni_0.2Mo_0.8N(Ni-MoN).Through the electrochemical property tests,the Ni-MoN catalyst was found to exhibit excellent activity and stability towards both HER and OER.