Enhanced photocatalytic reduction of CO2 over pg-C3N4-supported TiO2 nanoparticles with Ag modification

Photoreduction of CO2 has been a promising route to decrease CO2 emission and obtain valuable fuels or chemical raw materials, but it still faces tremendous challenge. Composite catalyst fabricated with TiO2 and g-C3N4 might exhibit great competitive advantages, due to their potential application prospects in the field of photocatalysis. Herein, we prepared a novel pg-C3N4/Ag-TiO2 composite catalyst by using the porous defective g-C3N4 (pg-C3N4) and Ag doped TiO2, and a three-component S-scheme heterojunction had been built. Compared to individual g-C3N4 or Ag-TiO2, the synthesized pg-C3N4/Ag-TiO2 material demonstrates significantly increased photocatalytic activity for the reduction of CO2 and the AQE reaches 2.364%. In addition to improved charge separation efficiency of S-scheme heterojunctions, increased surface area of the catalyst could also be responsible for the enhanced photocatalytic performance. Experimental and computational reveals that when Ag is added to TiO2, its work function is adjusted, and electrons are transferred in a different direction, promoting the formation of S-scheme heterojunctions.