Synthesis Of Metastable Ni-based Electrocatalyst For Water Splitting

In order to achieve the goal of"carbon peak,carbon neutral"on schedule and meet the demand for energy for rapid economic development,it is urgent to develop low-carbon,efficient and pollution-free energy.Renewable energy electrolysis of water for hydrogen production is considered to be the most promising hydrogen production method in the future due to its mild reaction conditions,high purity and no pollution.Electrolyzed water consists of two half reactions:oxygen generation reaction（OER）and hydrogen evolution reaction（HER）.It is particularly important to develop electrolyzed water catalysts with low price,higher catalytic activity and longer stable time.The main research contents of this paper are as follows:（1）Synthesis of ultra-thin Fe-Ni（OH）₂ nanosheets by simple solvothermal method,we used plasma topology conversion of Fe³⁺doping Ni（OH）₂ nanosheets to porous hcp Ni engineered by Fe Ox clusters.X-ray absorption fine spectra established that they are formed via Ni-O-Fe bonds,thus metal oxide-metal interfaces with benign geometry and electronic structures enable it to be efficient electrocatalyst,η₁₀=226 m V.In situ Raman show that the interfacial action of Fe Ox cluster with Ni can stimulate the generation of intermediateγ-Ni OOH,effectively promoting OER rate.DFT calculation further demonstrates the interaction accelerates the desorption of O₂ molecules on the surfaces.（2）We firstly synthesize three-dimensional Pt-Ni（OH）₂ nanospheres precursors by hydrothermal technology,then we used plasma topology conversion of Pt⁴⁺doping Ni（OH）₂ nanoflowers to porous hcp Ni Pt nanoflowers.The valence and coordination environment of platinum by aberration-corrected high resolution electron microscopy and in-situ X-ray absorption fine structure characterization.It is confirmed that platinum is atomically dispersed and exists in the form of Pt-Ni bond,forming nickel-platinum monatomic alloy.During the electrochemical oxygen evolution reaction process,the valence state of nickel increased.The Ni-Ni and Ni-O bond length becomes shorter,which proves the evolution process ofγ-Ni OOH.This novel structure creates the possibility to construct the bifunctional sites.The overall electrochemical water splitting is only 1.46 V at 10 m A cm^-2.DFT calculation also shows that the introduction of Pt atom weakens the adsorption of hexagonal nickel on oxygen molecules and improves the reaction efficiency.（3）Ni（OH）₂ nanosheet precursors were synthesized by hydrothermal technology,and then treated by CH₄（producing*H,*CH,*CH₂,*CH₂CH₂,etc.）and Ar/H₂（producing*H only）plasma.By controlling the reaction conditions,hexagonal phase and cubic phase Ni nanosheets were synthesized respectively to study the stabilization of carbon species.The interaction between carbon species and reactants in the intermediate reaction process was analyzed by various characterization methods,and the stable formation mechanism of carbon induced metastable phase（hcp）was proposed.DFT calculation was used to compare the effects of carbon species on the disordered arrangement of Ni atoms,which provided a theoretical basis for the growth mechanism of carbon induced stable hcp Ni from the perspective of molecular dynamics.