Synthesis Of Phosphorus-doped Carbon-supported Bimetallic Phosphides And Their Application In Electrocatalysis

Nowadays,renewable clean energy（e.g.,wind energy,tidal energy,solar energy）has partially replaced fossil fuels to alleviate energy crisis and environmental pollution.However,limited by the characteristics of renewable energy,such as geographical,oceanic,or intermittent,the development of energy storage and conversion system has become one of the critical aspects of using renewable energy at present.Hydrogen is regarded as an ideal energy carrier in the future low-carbon society due to its high energy density and zero-carbon emissions.Electrocatalytic overall water splitting（OWS）is considered a sustainable cleaning technology for hydrogen production,but it is still restricted by the sluggish kinetics of anode oxygen evolution reaction（OER）.Hydrazine oxidation reaction（Hz OR）requires a lower thermodynamic oxidation potential and does not produce carbon molecules,making it one of the options to replace OER for energy-efficient hydrogen production.In addition to hydrogen,biomass as a sustainable carbon source can also replace or complement petroleum-based fuels as a feedstock for the production of downstream value-added chemicals and catalytic conversion to biofuels.To date,a large number of noble metal-based materials,such as Pt,Ru,and Ir,have been used commercially as the benchmark catalysts for these catalytic conversions.However,the scarcity and high cost of these noble metal-based materials have severely hindered their practical application.So far,the research on electrochemical water splitting and catalytic conversion of biomass mainly focuses on the developing and designing catalytic materials with high stability,high efficiency,and low cost.This dissertation used low-cost transition metal phosphides to study one-dimensional P-doped carbon supported cobalt-doped nickel phosphide composites for electrocatalytic hydrazine oxidation-assisted water splitting for hydrogen production,and P-doped carbon supported copper-nickel phosphide composites bimetallic as the catalysts for catalytic conversion of biomass.The details of the study are as follows:（1）Herein,a Co Ni-bimetal phosphide nanoparticles embedded P doped carbon matrix structure((Co_0.6Ni_0.4)₂P@PC)is constructed via annealing a novel precursor composed of Co Ni-bimetal sites and P contained ligands for hydrazine-assisted water splitting.The P element can simultaneously in situ phosphorize the metal sites and carbon atoms.The(Co_0.6Ni_0.4)₂P@PC exhibits outstanding hydrogen evolution reaction（HER）performance with an overpotential of 67.9 m V at 10 m A cm^-2 and requires an ultralow potential of-83 m V at 10 m A cm^-2 for Hz OR in alkaline electrolyte.(Co_0.6Ni_0.4)₂P@PC exhibits excellent electrocatalytic activity and stability for HER over a wide p H range.Furthermore,the electrolyzer assembled with the(Co_0.6Ni_0.4)₂P@PC as both cathode and anode delivers a cell voltage of merely 0.048 V,which is much lower compared with the OER-HER system（1.60 V）for reaching 10m A cm^-2.The present work develops an eco-friendly synthetic method for designing a low-cost and highly efficient carbon matrix incorporated phosphide electrocatalyst for energy-saving hydrogen production.（2）Electrocatalytic hydrogenation（ECH）can convert biomass-derived molecules containing unsaturated functional groups into high-value fine chemicals and biofuels.Still,the efficient targeted catalytic conversion of biomass remains highly challenging due to the lack of efficient and stable non-precious metal catalysts.In this work,we reported a simple and controllable synthesis method to prepare a P-doped carbon-based bimetallic phosphide（Cu Ni P@PC）catalyst.Cu Ni P@PC is used for a furfural hydrogenation reaction（FHR）to produce economic furfuryl alcohol（FAL）in an alkaline medium.Electrochemical tests confirm that the Cu Ni P@PC could convert most biomass-derived furfural to furfuryl alcohol with conversion rate and selectivity over 80%,and maintain excellent activity after four cycles.The results indicate that Cu Ni P@PC has an excellent activity towards electrocatalytic hydrogenation on furfural.