Preparation And Application Of Graphene Semiconductor Composites In Catalytic Hydrogen Production

With the development of industry,fossil energy increasing depleted,environmental pollution becoming increasingly serious,and resulting shortage of energy and environmental pollution which are two major problems faced by humanity today.The search for alternative new energy sources is imminent,and hydrogen energy is considered to be one of the most ideal new sources of energy in the 21st century due to its cleanliness and sustainability.However,the traditional hydrogen production technology consumes a lot of energy,and the hydrogen production efficiency is low.Among the many hydrogen production methods,photocatalytic hydrogen production and electrocatalytic hydrogen production are the two most efficient ways to produce hydrogen.At present,although platinum?Pt?as a catalyst exhibits excellent catalytic performance in the catalytic hydrogen production reaction,its high price and scarce reserves largely limit the large-scale application.Graphene has attracted extensive attention due to its excellent conductivity and large specific surface area.It has become a research hotspot to improve the catalytic performance of composite catalysts by compounding graphene with catalytic materials.This paper studies the application of graphene-semiconductor composites in the field of catalytic hydrogen production.The specific research content includes the following two aspects:InChapter3,AuandTiO₂QDswereusedtosynthesize three-dimensional graphene composites?Au@TiO₂@3DGFs?as a catalyst for photoelectrocatalytic hydrogen production by electrodeposition.A series of characterizations and photoelectrocatalytic performance tests were performed.Through comparative experiments we found the optimum doping amountof Au.Theexperimentalresultsshowthatthecomposite Au@TiO₂@3DGFs has an amazing photoelectrocatalytic?PEC?activity and stability:Under the condition of the applied visible light irradiation with100 mW/cm² of light intensity and a low overpotential of-240 mV,the current density of the Au@TiO₂@3DGFs photoelectrode reached 90 mA/cm²,which is 3.6 times of the natural current density.In addition,the current density rose to 95 mA/cm² after continuous operation for 90 hours under lightconditions.Therefore,thecompositecatalystswhichweare investigating are expected to be used in large scale in hydrogen production.In Chapter 4,we synthesized a Ni quantum dot-doped MoS₂ composite?Ni@MoS₂@Graphene?using graphene as a support for the electrocatalytic hydrogen production through hydrothermal and atomic layer deposition techniques.A series of characterization and electrocatalytic performance tests were performed.The experimental results show that the composite Ni@MoS₂@Graphene has excellent hydrogen evolution reaction?HER?activity and stability:the current density reaches 34 mA/cm²at an overpotential of-216 mV,under the condition of a constant overpotential of-224 mV and the continuous operation of the composite electrode for 100hours,the current density did not decrease but gradually increased.Therefore,the graphene composite material prepared by this simple preparation method has the advantages of low cost,economical feasibility,and lays a foundation for the subsequent large-scale industrial application.