Doping engineering in S-scheme composite for Regulating the selectivity of photocatalytic CO reduction.

Regulating product selectivity in photocatalytic CO reduction to enhance the yield of valuable hydrocarbons remains a formidable challenge because of the diversity of reduction products and the competitive reduction of HO. Herein, ultrathin BiO/ Co-doped SrBiTiO S-scheme photocatalysts (Co-BS) were synthesized using a hydrothermal method. The BiO/Co-doped SrBiTiO photocatalyst exhibited significantly higher selectivity for CH (62.3 μmolg) and CHOH (54.1 μmolg) in CO reduction compared with pure SrBiTiO (27.2 and 0.8 μmolg) and the BiO/SrBiTiO S-scheme without Co (30.2 and 0 μmolg). The experimental results demonstrated that the inclusion of Co into SrBiTiO expanded the range of light absorption and generated an internal electric field between Co-doped SrBiTiO and BiO. Density functional theory calculations and other experimental findings confirmed the formation of a new doping energy level in the BiO/SrBiTiO S-scheme heterojunction after Co doping. The valence band electrons of BiO/SrBiTiO transitioned to the Co-doped level because of the interconversion between Co and Co under the action of the internal electric field. Furthermore, the corresponding characterizations revealed that the adsorption and electron transfer rates of the surface active sites were accelerated after Co doping, enhancing electron involvement in the photocatalytic reaction process. This study presented a metal-doped S-scheme heterojunction approach for CO reduction to produce high-value products, enhancing the conversion of solar energy into energy resources.