Synthesis Of Ni-based Nanocomposites And Their Enhanced Electrocatalytic Activity For Oxygen Evolution Reaction

It is a serious challenge to develop effective energy in modern society.The problems of global warming,harmful emissions and environmental degradation arise from the usage of unsustainable energy,including oil,natural gas and coal et al.The development trend of modern society is to replace fossil fuels with clean energy.However,these renewable energy sources are affected by weather.seasons and regions.It is necessary to integrate the electrocatalytic energy storage and conversion system for solving the problem of renewable energy continuity.The oxygen evolution reaction(OER)is an important electrode reaction in energy storage and conversion equipments(eg.fuel cells,metal-air batteries and water splitting devices),while it requires a large overpotential due to thermodynamic and kinetic impediments during the reaction process.Therefore,the synthesis of highly efficient and conductive non-precious metals-based electrocatalysts is the current research hotspot in this field.The construction of a three-dimensional self-supported electrode in situ in the non-expensive metal substrate can avoid the extra overpotential generated by the interface between the electrocatalyst and substrate,so as to reduce the overpotential.1.Incorporating nitrogen-doped graphene quantum dots and Ni3S2 nanosheets:a synergistic electrocatalyst with highly enhanced activity for oxygen evolution reaction.In this work,we prepared a three-dimensional non-noble metal catalyst.The self-doped nitrogen graphene quantum dots(NGQDs)were fabricated by the biomass as the raw material,in turn with the hydrothermal,pyrolysis,microwave and other treatment,and incorporated it with the Ni3S2 nanosheets grown in situ on foam nickel to form a nanocomposite(Ni3S2-NGQDs/NF).The nanocomposite shows an overpotential of only 216 mV at the current density of 10 mA cm-2 in alkaline electrolytes.It is a promising catalyst for OER with comparable catalytic performance to the commercial RuO2 catalyst.2.Synergistic effect of NiOx and nitrogen-doped graphene quantum dots nanocomposites(NiOx-NGQDs/NF)and its improved catalytic activity for oxygen evolution reaction.On the basis of work one,the new technology of oxidation etching is introduced to further improve the catalytic performance by increasing the electrocatalytic active area.Selecting the appropriate experimental conditions,the oxygen evolution reaction(OER)performance of the catalyst reached a good level,and the mechanism and process of material formation were explored.The structure,size,morphology and composition of NGQDs and nanocomposites were characterized by X-ray powder diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS),Fourier transform infrared spectroscopy(FT-IR),and solid-state fluorescence spectroscopy.At the same time,the catalytic performance of NiOx-NGQDs/NF was studied and found with improved OER performance.