Preparation Of Rare Earth Modified Nickel Sulfide Electrocatalysts And Tts Electrocatalytic Oxygen Evolution Performance

Currently,as the world is suffering from severe energy shortages and environmental pollution,it is urgent to develop green and sustainable energy sources.As an ideal clean energy source,hydrogen energy is renewable,light in mass and high in energy density,and it can effectively replace traditional fossil energy sources.Electrochemical water splitting technology is a highly efficient and promising technology for green hydrogen production.The entire water-splitting process consists of a cathodic hydrogen evolution reaction（HER）and an anodic oxygen evolution reaction（OER）.This method is simple and environmentally friendly,and has application potentia.However,in practice,the electrocatalytic hydrolysis reaction is limited by the slow kinetics and high energy consumption of the anode oxygen evolution process.Therefore,reducing the anodic overpotential without affecting the overall efficiency and stability is the key to improving the efficiency of electrocatalytic hydrolysis and to producing clean energy on a large scale.As a class of low-cost,easy-to-synthesize and highly active transition metal materials,nickel sulfides have shown great potential in replacing precious metal electrocatalysts.Among many nickel sulfides,Ni₃S₂ has become a current research hotspot because of its good metallicity,high conductivity,good reversibility and environmental performance due to the continuous Ni-Ni bond in its structure.In this paper,a series of Ni₃S₂based hydrolysis catalysts were modified by compositing with Gd（OH）₃,La doping and La,Gd co-doping,and their OER performances and electrocatalytic mechanism were evaluated with the aim of improving the catalytic efficiency of Ni₃S₂.（1）Gd（OH）₃/Ni₃S₂/NF with excellent OER performance was obtained by growing Gd（OH）₃/Ni₃S₂ on nickel foam.directiy The spherical Gd（OH）₃ nanoparticles evenly distributed on the 1D Ni₃S₂ nanobelts not only increase the hydrophilicity significantly,but also induce more oxygen vacancies,thus showing a better electrocatalytic performance than pure Ni₃S₂.Gd（OH）₃/Ni₃S₂/NF has an overpotential of 252 m V at 50 m A cm^-2,a Tafel slope of 47 m V dec^-1,and good stability in alkaline solutions.（2）La-Ni₃S₂/NF nanorod arrays were successfully synthesized by a hydrothermal method.Experiments showed that with the doping of La,the morphology of Ni₃S₂ is transformed from nanofold to nanorod,and La doping can accelerate the electron transfer between Ni atoms and optimize the electronic structure,which significantly improved the electrocatalytic activity of OER.At a current density of 20 m A cm^-2,the overpotential is 290 m V and the Tafel slope is 57m V dec^-1.Compared with the noble metal Ru O₂/NF electrocatalyst,La-Ni₃S₂/NF exhibites superior electrocatalytic activity as well as electrocatalytic stability.（3）To further investigate the effect of elemental doping on the performance of Ni₃S₂,La,Gd co-doped Ni₃S₂ nanowire arrays（La,Gd-Ni₃S₂/NF）were prepared by a one-step hydrothermal method in this chapter.It was found that La and Gd co-doping could not only modulate the microscopic morphology of the electrocatalyst but also increase the hydrophilicity of the material.The results shows that the overpotential of La,Gd-Ni₃S₂/NF is 292 m V at 100m A cm^-2 current density and the Tafel slope is 59 m V dec^-1,which is much lower than that of La-Ni₃S₂/NF(380 m V,95 m V dec^-1),Gd-Ni₃S₂/NF(340 m V,88 m V dec^-1),Ru O₂/NF(400 m V,111 m V dec^-1)and pure Ni₃S₂/NF(420 m V,142 m V dec^-1).These results not only provide a new strategy for the design of nickel-based transition metals,but also provide some reference for the construction of catalysts in other application areas.