Preparation Of MXene And CdIn₂S₄-based Composite Photocatalysts And Study On Their Catalytic Organic Synthesis

Photocatalytic selective oxidation of aromatic alcohols to aromatic aldehydes has always been a hotspot in photocatalytic research.The transition metal nickel phosphide has the advantages of high hydrogen production activity and long-term stability,so it is considered a good hydrogen evolution catalyst.Therefore,we have synthesized a bifunctional catalyst that can simultaneously achieve benzyl alcohol to benzaldehyde and to produce hydrogen under visible light.First,we explored the optimal synthesis temperature of CdIn₂S₄ by solvent method,and synthesized 520nm Ni₂P nanoparticles by solvothermal method after grinding.Ni₂P/CdIn₂S₄ composite catalyst was synthesized using a secondary solvent.According to the experimental results,the optimal loading was 5%Ni₂P/CdIn₂S₄.After 4 hours under visible light irradiation,The yields of H₂ and benzaldehyde were 592.4?mol/h and 639.1?mol/h,which were 10.0 and 8.8 times that of pure CdIn₂S₄?59.0?mol/h H₂ and 72.72?mol/h benzaldehyde?.The utilization rate of photo-generated electron-hole pairs is 92.8%.We have developed a highly efficient use of photo-generated electrons-hole pair carries out the system of aromatic alcohol to generate aromatic aldehyde and hydrogen evolution.According to the analysis of experimental results,when visible light is irradiated to the surface of the CdIn₂S₄ photocatalyst,electron-hole pairs are generated.Most of the electron-hole pairs are directly recombined,and a few are used to oxidize benzyl alcohol and to reduce H⁺.When a small amount of Ni₂P nanoparticles are added,more electron-hole pairs will be released,and the increase of the forbidden band width will lead to an increase in the electron-hole pair recombination distance.Due to the adsorption of electrons by Ni₂P nanoparticles,the electrons and holes will be sufficient separation.The photogenerated holes in the valence band first interact with benzyl alcohol to form an active intermediate{Ph?CH?OH?}.The generated intermediate will be oxidized by another hole to form benzaldehyde and release two hydrogen protons?H⁺?;two Hydrogen protons?H⁺?are directly reduced to H₂ by photo-excited electrons on the surface of Ni₂P particles and CdIn₂S₄ photocatalyst.We used aromatic alcohol benzyl alcohol to evaluate catalyst performance and explored other catalysts around non-aromatic alcohol 5-hydroxymethylfurfuryl alcohol.Everyone knows,Selective oxidation of 5-hydroxyfurfural?HMF?to the corresponding aldehyde and acid is one of the key reactions in the production of chemical products using biomass and derivatives.In recent years,the emerging Ti₃C₂T_x is a two-dimensional titanium carbide material,due to the metallic properties and hydrophilic surface of Ti₃C₂T_x,It is widely used in photochemistry and electrochemistry,but selective oxidation of non-aromatic alcohols and aromatic alcohols has not been reported yet.In this paper,we have prepared a new photocatalyst Ti₃C₂Tx/g-C₃N₄?MX/CN?composite by evaporation induced self-assembly.Selective oxidation of non-aromatic alcohol HMF to DFF to evaluate photocatalytic activity.Under air atmosphere,room temperature and visible light irradiation at 400 nm,Use 6%MX/CN as a catalyst and photoreaction for 10 hours,the conversion rate was 96%selectivity yield was 96%.In order to further study the trial range of the catalyst,we achieved a selective oxidation of the aromatic alcohol p-methoxybenzyl alcohol to p-methoxybenzaldehyde,under the same conditions,photoreaction for 2 hours,the conversion rate was 86%selectivity yield was 96%.The reactive species are·O₂^-and h⁺.PL shows 6%MX/CN exhibits lower combination of electrons and vacancies with g-C₃N₄,due to Ti₃C₂T_x can aggregate electrons.This study provides a way to enhance g-C₃N₄ utilization under mild conditions.