Preparation Of Metal Based Composite Catalysts And Study On Electrocatalytic Properties

As a clean and sustainable energy source,hydrogen is an ideal alternative to fossil fuels.Hydrogen produced by electrocatalytic water splitting has been widely concerned due to the extensive raw materials and non-polluting by-products.The hydrogen production by electrocatalytic water splitting consists of a hydrogen evolution reaction?HER?at the cathode and an oxygen evolution reaction?OER?at the anode.Both the HER and the OER need to overcome excessive reaction energy barriers,which results in high overpotential and low conversion efficiency.Noble metals and their oxides are recognized as the most effective catalysts for reducing the overpotential of HER and OER.However,the noble metal are small reserves and expensive,which severely limits its large-scale application.Therefore,it is of great significance to develop efficient and abundant electrolytic catalysts.Based on this,trace ruthenium-doped cobalt-based composite catalyst and Ni₂P/Mo S₂ composite catalyst are designed and prepared.?1?A nitrogen-doped carbon encapsulate Ru Co alloys catalyst?Ru Co@NC-750?was prepared by hydrothermal,impregnation and high-temperature roasting process.A small amount of Ru?1.56 wt%?modified the Co lattice matrix to form the active Ru Co alloy crystal form.The nitrogen-doped carbon layers benefit from the activation of the Ru Co alloy and generates catalytic active sites that are favorable for proton adsorption and reduction.Ru Co@NC-750 shows excellent catalytic performance for HER in a wide p H range and OER in alkaline media.At the current density of 10 m A cm^-2,it sows the overpotentials of 25 m V?1.0 M KOH?,29 m V?0.5 M H₂SO₄?,and 163?1.0M PBS?m V for HER,and 308 m V?1.0 M KOH?for OER.Meanwhile,when the Ru Co@NC-750 catalyst serves as the anode and cathode materials in a two-electrode electrolytic cell,it needs only 1.54 V to achieve a current density of 10 m A cm^-2?vs RHE?.A series of characterizations prove that the excellent catalytic performance of the Ru Co@NC-750 catalyst can be attributed to the optimization of the nitrogen-doped carbon layer by the active Ru Co alloy,which is conducive to the electron transfer and adjust the carbon-hydrogen bonding.This work provides a new idea for the preparation of highly active and low cost catalysts for overall water splitting.?2?A three-dimensional?3D?heterogeneous catalyst of hollow nickel phosphide spheres coupled with molybdenum sulfide nanosheets?Ni₂P@Mo S₂?were prepared by using hollow Ni₂P spheres as a template and Mo S₂ sheets was loaded on the surface of though a hydrothermal method.Benefiting from the hollow spherical structure and the coupling effects between Mo S₂ and Ni₂P,Ni₂P@Mo S₂catalyst shows superior activity for hydrogen generation over a wide p H range.It displays overpotentials of 181,269and 535 m V in 1.0 M KOH,0.5 M H₂SO₄ and 1.0 M PBS at a current density of 10m A cm^-2,respectively.A series of characterization demonstrate that the strong coupling interaction between Ni₂P and Mo S₂ effectively optimizes the electronic structure of the Ni₂P-Mo S₂ 3D/2D interfaces,beneficial for regulating H*adsorption energy.This work offers a novel strategy for enhancing the HER performance of metal phosphide/sulfide catalysts by constructing heterostructured materials with abundant3D/2D interfaces.