Bi₁₂TiO₂₀-TiO₂ S-scheme heterojunction for improved photocatalytic NO removal: Experimental and DFT insights

The fabrication of step-scheme (S-scheme) photocatalysts with superior redox ability for air purification is very important but remains a challenge. In this study, an S-scheme Bi₁₂TiO₂₀-TiO₂ heterojunction is prepared for photocatalytic NO removal. The optimized Bi₁₂TiO₂₀-TiO₂ heterojunction shows higher NO removal efficiency (42.6 %) than that of pristine Bi₁₂TiO₂₀ (8.7 %) and TiO₂ (21.4 %) under simulated solar light irradiation. The enhanced photocatalytic activity can be attributed to the efficient separation and transfer efficiency of photoinduced electrons-hole pairs, enhanced redox ability, and increased NO adsorption capacity induced by S-scheme heterojunction between Bi₁₂TiO₂₀ and TiO₂. The S-scheme charge transfer mechanism on Bi₁₂TiO₂₀-TiO₂ heterojunction is proposed based on characterizations and theoretical calculations. The NO conversion process is investigated using in-situ Fourier transform infrared spectroscopy (in-situ FTIR). This study provides new insights for exploring highly efficient photocatalysts for NO removal.