Dual-functional copper (Cu0/Cu2+)-modified SrTiO3-δ nanosheets with enhanced photothermal catalytic performance for CO2 reduction and H2 evolution

In recent years, metal–semiconductor heterojunctions have been intensively researched in the field of photocatalysis due to the effective spatial separation of photo-induced electron-hole pairs. Here, the dual-functional copper (Cu0/Cu2+)-modified SrTiO3-δ nanosheets (Cu/STCO) are successfully synthesized by a two-step route. First, Cu2+-doped SrTiO3-δ (STCO) nanosheets are synthesized by a hydrothermal method and then Cu0 nanoparticles (NPs) are in situ formed from the STCO under H2 atmosphere at 500 °C. The optimized ratio 6 %-Cu/STCO photocatalyst exhibits the best photothermal catalytic performance for CO2 reduction reaction (CO2RR) and H2 evolution performance. The detailed characterization demonstrate that the Cu2+ dopant extend the light absorption range and the in situ generated Cu0 NPs effectively improve the separation ability of photogenerated charge carriers by forming the Schottky contact with STCO. The excited localized surface plasmon resonance (LSPR) effect of metallic Cu0 in Cu/STCO shows a considerable catalysis performance even under 600 nm monochromatic light irradiation. The density functional theory (DFT) calculations suggest that the Cu/STCO diminishes the barrier of the rate-determining steps of the CO2RR and H2 evolution thus perform the outstanding catalysis ability in two filed. This work presents the synergistic effect of Cu0 and Cu2+ on enhancing the photothermal catalytic performance for CO2RR and H2 evolution and offers a novel strategy to synthesize the metal–semiconductor nanostructures for efficient harnessing of solar energy into fuel.