The Study On Oxygen Evolution Propreties Of Cerium-modified Nickel-based Electrocatalytic Materials

Hydrogen energy is expected to be a secondary energy source,due to characteristics of environmental friendliness and sustainable development.Electrolysis of water is the most viable way to obtain hydrogen energy.In the process of electrolysis of water,oxygen evolution reaction（OER）is an anode reaction and the main bottleneck.Efficient noble metal-based catalysts are OER benchmark catalysts,but their high cost and scarcity limit the wide application.Therefore,it is highly anticipated to develop non-precious metal catalyst materials with affordable costs,abundant earth reserves,and high efficiency and stability.Studies have found that nickel-based catalysts show suitable affinity for oxygen-containing intermediates during OER,and are expected to become non-noble metal-based electrocatalysts.However,OER performances of nickel-based catalysts are satisfied enough.Cerium-modification is an effective way to improve the OER performance.Based on this,this dissertation mainly includes the following two parts:Construction of composite structures is an effective way to improve the catalytic activity of OER.Firstly,the structure of Ni-MOF nanosheets have been grown on Ni foam（NF）by hydrothermal method.Then,the Ce-modified Ni（OH）₂nanoparticles were anchored on the Ni-MOF nanosheets by electrodeposition to form Ce-m-Ni（OH）₂@Ni-MOF self-supporting electrodes.Raman spectroscopy proved that both Ce（OH）₃and Ce doping are present in Ce-modified Ni（OH）₂nanoparticles.The self-supporting electrode can achieve a current density of 50 m A cm^-2at an ultra-low overpotential of 216 m V,and can operate continuously for 30 h at a current density of100 m A cm^-2without significant reduction.The Ce-m-Ni（OH）₂@Ni-MOF electrode has excellent OER performance,thanks to the Ce-m-Ni（OH）₂@Ni-MOF composite structure with an open nanosheet-like structure,the connection between Ni-MOF and Ce-m-Ni（OH）₂,and synergy between Ni and Ce.Secondly,in order to further improve the catalytic activity of OER,Ni₂S₃nanosheets with good conductivity were used as substrates,and then Ce（OH）₃/Ni（OH）₂were deposited to prepare Ce（OH）₃/Ni（OH）₂@Ni₂S₃composite structure.Structure and morphology of samples were charactrized by XRD and SEM.The analysis of electrochemical performance showed that Ce（OH）₃/Ni（OH）₂@Ni₂S₃showed excellent performance:it only needs 252 m V overpotential to reach a current density of 50 m A cm^-2in 1.0 M KOH solution,and it could operate stably for 24 h at a current density of100 m A cm^-2.