Studies On The Controllable Synthesis Of Nickel Hydroxylphosphate Single-wall Nanotubes And Their Electrocatalytic Performance

Development of efficient electrocatalysts for oxygen evolution reaction（OER）is of great significance for future renewable energy applications.Compared with traditional nanomaterials,ultrathin nanomaterials have a strong size effect,thus showing more prominent physical and chemical properties.Because of the unique one-dimensional hollow structure and ultrathin wall-thickness,single-wall nanotubes are popular materials in this field.This paper is based on the controlled synthesis of nickel hydroxylphosphate single-wall nanotubes,the OER performance was studied by post-modification of the nanotubes and in-situ growth on the conductive substrate.We also explore the relationship between properties and the structure,composition of the nanomaterials.Nickel hydroxylphosphate single-wall nanotubes have been prepared by a surfactant-free solvothermal strategy in DMF-H₂O solvent system,which possess diameters of about 5 nm and lengths of about several micrometers.A surface-coating method was used to modify the nanotubes,and iron hydroxides on the surface of the nanotubes was coated uniformly.The morphology,composition,and electrocatalytic property before and after the deposition of iron hydroxides onto the NiPO SWNTs were investigated in detail.Our results demonstrated that the OER activity of NiPO/Fe（OH）x SWNTs with different Fe contents exhibited a volcano-type shape.Benefiting from the ultrathin nanostructure and the synergistic effect between iron hydroxides and NiPO SWNTs,the optimized samples have achieved excellent electrocatalytic performance.In-situ growth of the nickel hydroxylphosphate single-wall nanotubes in nickel foam was successfully synthesized by using nickel foam as nickel source and substrate.The structure and composition of the materials were determined by characterization.The NiPO/NF as the effective electroactive material assisted by the nickel foam substrate,the OER performance shows the large current density and long time stability.