Structurally designable Bi₂S₃/P-doped ZnO S-scheme photothermal metamaterial enhanced CO₂ reduction

In this study, a novel 3D Bi₂S₃/P-ZnO S-scheme gyroid metamaterial was prepared by 3D printing and the hydrothermal method. The unique gyroid macrostructure and nanoarray microstructure offer a large volume of active sites for the photothermal catalytic reaction, thus improving the overall utilization rate of light. ZnO obtained by sintering the precursor produces oxygen vacancies, primarily due to P doping. This enables it to have a photothermal effect. After loading Bi₂S₃, the photothermal effect of P-ZnO and Bi₂S₃ is coupled, further increasing the surface temperature of composite structure and speeding up the reaction rate. P-ZnO and Bi₂S₃ formed a S-scheme heterojunction, promoting the separation and transfer of photogenerated carriers. Under simulated sunlight, the CO and CH₄ yield of Bi₂S₃/P-ZnO S-scheme gyroid metamaterials are 8.87 and 1.49 μmol h⁻¹. These are 3.45 times and 4.65 times of P-ZnO gyroid structure, respectively. Through SEM, TEM, XPS, ESR and in-situ FTIR characterizations, the transfer paths of photogenerated carriers between heterojunctions were revealed, and the reaction paths of photothermal catalytic CO₂ reduction were explored. The co-design of 3D structure and material allows for a novel concept for further improving photothermal catalytic performance.