Design And Preparation Of Metal Sulfur/oxide And Its Photo/electrocatalytic Performance Studies

The rapid development of the economy has been accompanied by the depletion of fossil fuels.Therefore,finding green and renewable energy sources is of practical significance for national economic development and achieving"carbon neutrality"as soon as possible.Catalytic technology,as one of the important means to solve environmental pollution control and new energy shortage problems,has received increasing attention and research.The use of photocatalysis to convert solar energy into chemical energy by decomposing water,as well as the synthesis of fine chemicals from biomass as raw materials through electrocatalysis,is an effective way to reduce dependence on fossil fuels.However,existing photocatalytic and electrocatalytic materials cannot achieve large-scale commercial applications due to their low efficiency.Therefore,improving the catalytic efficiency of materials is one of the key issues that need to be addressed urgently.Although noble metal catalysts have excellent performance,their application is limited due to their high cost.Metal sulfides/oxides have attracted attention because of their excellent catalytic activity,simple preparation,and abundant reserves.Therefore,this article focuses on studying photocatalytic materials such as BS,Mo SSe,Al S,and Zn O and uses first-principles calculations to reveal the physical mechanism and key influencing factors of the differences in photocatalytic activity of these materials.The article also describes the migration of carriers and band edge potentials in materials at the atomic scale,speculates on the redox reactions that occur between photo-induced electrons and holes in the photocatalytic process,and discusses the possibility of using these materials in photocatalytic water splitting.Based on an understanding of photocatalytic water splitting,this study focuses on a new type of electrocatalytic material,Co-doped Ni₃S₂,and investigates the main factors that affect the oxidation ability and performance enhancement of 5-hydroxymethylfurfural（HMF）using this composite material as the research object.The main research contents of this paper are as follows:（1）Using the first-principles study,we investigated the geometric structures,electronic structures,and carrier mobility of monolayer and single-walled BS nanotubes.Compared with the monolayer structure,the band gap of the nanotube is significantly reduced,effectively extending its absorption range to solar light.Moreover,the larger-diameter BS nanotubes meet the oxidation-reduction potential for water splitting and exhibit hole mobility as high as4684.61cm²V^-1s^-1,which is two orders of magnitude larger than the electron mobility.The larger difference in mobility further enhances the separation of photogenerated electron-hole pairs in BS nanotubes.This study primarily focuses on the application of BS nanotube materials as photocatalysts,providing new directions for expanding the practical range of BS materials.（2）This study systematically investigates the electronic properties and photocatalytic performance of Al X（X=S,Se）nanotubes as photocatalysts.The band gaps of the most thermodynamically stable Al S and Al Se nanotubes are smaller compared to their monolayer counterparts,effectively extending the absorption range of visible light.The effective mass values of electrons and holes in the nanotubes differ by one order of magnitude,reducing the recombination of photogenerated electron-hole pairs.The application of strain engineering can effectively regulate the redox potentials of Al X nanotubes,enabling spontaneous water-splitting reactions in acidic and neutral water solutions.These unique and excellent properties make Al X（X=S,Se）nanotubes a promising candidate for a new type of photocatalyst.（3）Based on the first-principles study,the electronic structure and photocatalytic performance of single-walled and double-walled Janus Mo SSe nanotubes under strain were investigated.It was found that the bandgap of Janus Mo SSe nanotubes can be effectively adjusted by applying strain,exhibiting an increasing and decreasing trend under compression and tension,respectively.Moreover,the bandgap of the constructed double-walled Janus Mo SSe nanotubes is smaller than that of single-walled nanotubes and exhibits a type-II band alignment,which enhances the electron-hole separation rate and further improves their photocatalytic performance.These results provide a promising platform for designing novel structured photocatalytic materials for water splitting.（4）Based on density functional theory（DFT）,the optimized geometry and electronic structures of single-walled and double-walled Zn O nanotubes were studied using hybrid functional B3LYP.The stability and band-edge positions of the nanotubes were calculated.It was calculated that the band gap of double-walled nanotubes increases with the increase of wall spacing.The results show that the morphology control can effectively adjust the bandgap of Zn O,and double-walled Zn O nanotubes may exhibit higher photocatalytic efficiency than single-walled nanotubes.This study further explores the traditional photocatalyst Zn O and explores the possibility of improving its photocatalytic performance,providing new impetus for the development of hydrogen energy to replace fossil fuels.（5）Co-doped Ni₂S₃ composite material was synthesized using the hydrothermal method.The introduction of Co atoms significantly improved the oxidation ability of Ni₂S₃ towards HMF,and the material showed excellent performance in practical reactions,maintaining high stability even after ten cycles.Compared with Ni₂S₃/NF,Co_0.004-Ni₂S₃/NF exhibited better morphology uniformity and sharper edges of the synthesized nanosheets,as Co ions acted as morphology regulators for Ni₂S₃.Co-Ni₂S₃/NF exhibited good HMF oxidation activity,requiring an overpotential of 1.08 V vs.RHE for the same current density,which was about 92m V lower than that of Ni₂S₃/NF.The C_dl of Co_0.004-Ni₂S₃/NF was 52.51 m F cm^-2,much higher than that of Ni₂S₃/NF at 32.42 m F cm^-2,as the cross-nanoplate array structure provided Co_0.004-Ni₂S₃/NF with a larger specific surface area and more active centers.