Study On The Synthesis And Electrochemical Performance Of Self-supported Electrodes Composed Of Nickel-based Nanocatalysts

The overexploitation and heavy use of traditional fossil fuels will not only cause the rapid depletion of resources,but also result in serious environmental pollution.Therefore,it is urgent to find alternative clean energies.Hydrogen possesses a high energy density and burns cleanly without producing pollutants,which is one of the most ideal clean energies.Among all kinds of hydrogen production technologies,water electrolysis is a mature and pollution-free technology,which requires simple equipment and can produce hydrogen with high-purity.Water electrolysis is considered to be the mainstream technology of hydrogen production in the future.At the same time,electrochemical urea oxidation can not only utilize urea which exist in industrial wastewater and human and livestock urine as fuel to generate electricity,but also has a wide range of applications in the field of electrolytic hydrogen production.Nickel-based nanomaterials have been widely developed as electrocatalysts for water electrolysis and electrochemical urea oxidation due to their abundant reserves and excellent physical and chemical properties.In this dissertation,we studied the controllable preparation of several self-supported electrodes composed of Ni-based nanocatalysts and explored their potential applications in the field of energy electrocatalysis.The specific research contents and results are as follows:（1）A one-step for sulfuration and nitrogen-doping strategy was developed for the preparation of N-doped-Ni₃S₂/N-doped-Mo S₂ heteronanowires supported on Ni foam（N-Ni₃S₂/N-Mo S₂/NF）by using NiMoO₄ nanowires array growth on Ni foam（NiMoO₄/NF）as the starting material and thiourea as both sulfur and nitrogen sources.With the synergism of interface and electronic effects,the as-obtained N-Ni₃S₂/N-Mo S₂/NF self-supported electrodes showed enhanced electrocatalytic performance for both the hydroen evolution and oxgen evolution reactions in alkaline media.At the same time,the resultant composites exhibited excellent activity and stability when they were used as bi-functionnal electrodes for overall water splitting.（2）Low-Ir-doped Ni-based MOF ultrathin nanosheets in situ growed on Ni foam substrate（NiIr-MOF/NF）were synthesized by a one-step solvothermal method.The incorporation of a low content of Ir cations into the pristine Ni-MOF could bring about increased electrochemical active area,accelerated electron transport capability as well as improved chemical stability.With these advantages,the resulting NiIr-MOF/NF composite electrode exhibited highly efficient electrocatalytic performance for the urea oxidation reaction,accompanied with good stability and durability.（3）N-doped carbon-wrapped NiIr alloy nanoparticles composite nanosheets supported on Ni foam（NiIr@N-C/NF）were prepared by an annealing strategy using the pre-synthesized NiIr-MOF/NF as the precursor.The influence of different annealing tempretures on the morphology,structure and composition of the final products was investigated and the optimal annealing tempreture was found to be500°C.The resultant NiIr-MOF/NF-500 composites can be directly used as self-supported electrodes for effectively catalyzing the hydrogen evolution,oxygen evolution,as well as overall water splitting reactions.