Studies On The Synthesis Of Self-supporting Transition Metal Oxide Electrodes And Their Electrochemical Properties

The development and utilization of lithium ion battery and hydrogen energy is an effective way to solve the energy shortage and environmental problems.Transition metal oxide anode materials based on conversion reaction mechanism have attracted much attention due to their high capacity.In the development of hydrogen energy,the electrolytic water hydrogen production technology is efficient and direct.But limited by the performance of the electrolytic water catalyst,it is of great significance to study the efficient and low-cost transition metal catalyst that can replace the noble metal based catalyst.While the disadvantages of traditional powder materials can be improved by making self-supporting electrode by growing the active material directly on the conductive substrate.Therefore,3D foam metal was selected as the base material in this paper,and the active material was directly generated on the based substrate,and different series of self-supporting electrodes were prepared to be used as anode materials for lithium ion batteries and electrocatalysts for water splitting.The main contents are as follows:（1）NiO/NF anode materials were prepared by solvent heat method and oxidation treatment based on nickel foam（NF）,then NiO（P）/NF was obtained by phosphating,and then mixed with titanium before solvent thermal treatment and obtained NiO（Ti）/NF,NiO（Ti,P）/NF samples by the same method.The XRD results showed that only Ni and NiO crystal phase existed in the samples.Among them,NiO（Ti）/NF has the highest discharge capacity,which reaches 2.8 m A h/cm² after 50 cycles under the current density of 1 m A/cm².（2）Using NF as the based substrate,CuO/NF samples were prepared by solvent thermal method and oxidation treatment,and the solvent thermal reaction time was controlled（15,25,35h）.Among them,the capacity of CuO/NF-25h samples remains as high as 1.94 m A h/cm² after 50 charge and discharge cycles under the current density of 1 m A/cm².The interaction of NiO and CuO active material improves the capacity and stability of CuO/NF-25h electrode compared with that of NiO/NF sample.（3）N-doped Ni-MoO₂/NF self-supporting catalysts were synthesized by hydrothermal method and nitriding treatment at different temperatures with NF substrates.Ni-MoO₂/NF-5 has the best performance of HER,which shows a very low overpotential of 46 m V at 20 m A/cm².（Ni-MoO₂/NF-5）//（Ni-MoO₂/NF-4）overall water splitting device only need 1.53 V at a current density of 20 m A/cm²,which was30 m V better than（Pt-C/NF）//（Ir O₂/NF）.Moreover,the LSV curves of this overall water splitting device almost coincide after the 15-hour stability test,which has excellent stability performance.