Boosting Artificial Photosynthesis: CO₂ Chemisorption and S-Scheme Charge Separation via Anchoring Inorganic QDs on COFs

Photocatalytic conversion of CO2 into valuable hydrocarbon fuels holds great promise in addressing emerging energy shortages and environmental crises while fulfilling pressing societal and national development demands. Nonetheless, its efficiency is hindered by restricted CO2 chemisorption, rapid electron-hole recombination, and weak redox capability. Drawing inspiration from the distinctive characteristics of Schiff-based covalent organic frameworks (COFs), including substantial specific surface area, unique pore structure, and an abundance of weakly alkaline nitrogen elements, we employ the TPA-COF to enhance the chemisorption and activation of acidic CO2 molecules, as validated by the CO2-temperature-programmed desorption analysis. Furthermore, anchoring CsPbBr3 quantum dots (QDs) onto the COF facilitates the effective spatial separation of photoinduced charge carriers with strong redox capability, resulting from the formation of S-scheme heterojunctions between the COF and QDs as substantiated by in situ irradiation X-ray photoelectron spectroscopy, femtosecond transient absorption spectroscopy, and density functional theory simulations. As anticipated, the optimized COF/QDs heterostructures exhibit remarkable enhancements in CO2 photoreduction performance in the absence of any molecule cocatalyst or scavenger, yielding CO and CH4 at rates of 41.2 and 13.7 mu mol g(-1), respectively. This work provides valuable insights into the development of novel organic/inorganic heterojunction photocatalysts with CO2 chemisorption and S-scheme charge separation, offering great potential for sustainable artificial photosynthesis.