Construction of biochar assisted S-scheme of CeO2/g-C3N4 with enhanced photoreduction CO2 to CO activity and selectivity

The multi-interface contacted S-scheme photocatalyst was used for CO₂ reduction in this research. A hybrid nanostructures catalyst was constructed using g-C₃N₄ nanosheet, oxidized CeO₂ nanoparticles, and biochar (BIO, cattail-derived). The g-C₃N₄-BIO/CeO₂ catalyst exhibited high selectivity (> 95 %) in converting CO₂ to CO in a gas-solid-liquid phase CO₂ reduction system. Theoretical and experimental evidence suggests that the multi-interface and interfacial internal electric field (IEF) play a crucial role in enhancing electron transfer and redox ability in CO₂ reduction processes. Ce⁴⁺ species in CeO₂ have the capability to donate two electrons, facilitating the two-electron reduction process involved in the transformation of CO₂ to CO. Additionally, Ce⁴⁺ in CeO₂ acted as an electron trapping agent and could be reduced to Ce³⁺ ion after trapping electrons, which facilitated the separation process of photogenerated carriers inside CeO₂. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) demonstrated that COOH* intermediate played a key role as the rate determining step in the overall CO₂ photoreduction to CO. This investigation will contribute to the development and application of new and environmentally friendly BIO-based S-scheme photocatalysts.