Synthesis Of Pd-Cu/TiO₂ Nanosheet Catalysts And Their Photocatalytic CO₂ Reduction Properties

Photocatalytic CO₂ reduction is an ideal pathway for carbon resource conversion,which can be designed by photocatalysts to reduce CO₂ to hydrocarbon fuel for the purpose of utilizing CO₂ and mitigating the greenhouse effect.There are still problems of low product generation rate,poor product selectivity and high catalyst feedstock cost in the photocatalytic CO₂ reduction reaction.In this paper,Pd-Cu/TiO₂NS catalysts were prepared for the photocatalytic CO₂ reduction reaction,and the structural properties of the catalysts were characterized to investigate their catalytic performance in the catalytic reaction,to investigate the conformational relationship between catalyst structure and catalytic performance,and to establish a highly active,stable and selective photocatalytic CO₂ reduction system.In the paper,TiO₂ nanosheet carriers（TiO₂ NS）were prepared by exfoliation layering method,and Pd-Cu/TiO₂ NS catalysts were prepared by depositing the active metals Pd and Cu onto the surface of the carriers by photoprecipitation method.The effects of photodeposition time,photodeposition temperature,Pd loading,Cu loading,calcination temperature and carriers on the catalytic performance of the catalysts were investigated during the preparation process,and the preparation conditions of the catalysts were determined.The catalysts were characterized by XRD,SEM,TEM,XPS,FT-IR,UV-vis DRS,SPV,PL,EIS and Raman.The results show that the two-dimensional thin layer structure of the catalyst increases the dispersion of the active metal particles,shortens the migration distance of photogenerated electrons to the active metal,reduces the carrier loss,and facilitates the doping of the active metal components in the surface lattice,resulting in better photoelectric response performance and smaller forbidden band width;The Cu active components co-exist in the form of Cu O and Cu₂O,which are partially doped in the carrier surface lattice and partially wrap the Pd particles on the surface,forming high electron density Pd centers and high hole density Cu centers to improve the separation efficiency of photogenerated electron-hole pairs.The prepared 2 wt.%Pd-4wt.%Cu/TiO₂ NS-400°C catalyst was used in the photocatalytic CO₂ reduction reaction,and under the optimized reaction conditions,the average production rates of the photocatalytic CO₂reduction products CH₄ and CO were 1.15μmol·g^-1·h^-1 and 0.377μmol·g^-1·h^-1,and the selectivity of CH₄ was 92.43%,and the catalyst maintained good stability after five cycles.