Carbon-dots-mediated flexible inverse opal perovskite film featuring structural robustness and highly selective photocatalytic CO₂ reduction

Direct conversion of CO₂ to chemical fuels by photocatalysis has emerged as a promising strategy to alleviate global warming and renewable energy shortage issues. Halide perovskites with unique photoelectronic attributes show great potential for CO₂ photoreduction. However, their low photogenerated electron–hole efficiency and intrinsic structural instability in aqueous solution are still a significant challenge. In this work, we propose a universal facile strategy of robust carbon dots (CDs) mediated inverse opal perovskite (IOP) free-standing film, which is demonstrated as a uniform porous photocatalytic platform for efficient CO₂ photoreduction. Due to the grain boundary passivation effect of CDs, the mechanical strength and water resistance of CDs/IOP films are greatly improved. By the synergetic effects of IO structure and CDs cocatalyst, highly selective CO evolution rate of 60.25 μmol·g⁻¹·h⁻¹ from photocatalytic CO₂ reduction is achieved on typical CDs/CsPbBr₃ IOP film, which is 15.6 times higher than that of opal CsPbBr₃, since the enhanced lifetime of photogenerated electrons–holes and light/mass transfers. This work provides a new opportunity for robust and highly stable perovskite photocatalyst preparation to address the environmental and energy issues via an efficient photocatalysis process.