Engineering a CsPbBr3-based nanocomposite for efficient photocatalytic CO2 reduction: improved charge separation concomitant with increased activity sites.

Metal-halide perovskite nanocrystals have emerged as one of the promising photocatalysts in the photocatalysis field owing to their low-cost and excellent optoelectronic properties. However, this type of nanocrystals generally displays low activity in photocatalytic CO2 reduction owing to the lack of intrinsic catalytic sites and insufficient charge separation. Herein, we functionalized CsPbBr3 nanocrystals with graphitic carbon nitride, containing titanium-oxide species (TiO-CN) to develop an efficient composite catalyst system for photocatalytic CO2 reduction using water as the electron source. Compared to its congener with pristine CsPbBr3, the introduction of TiO-CN could not only increase the number of active sites, but also led to a swift interfacial charge separation between CsPbBr3 and TiO-CN due to their favorable energy-offsets and strong chemical bonding behaviors, which endowed this composite system with an obviously enhanced photocatalytic activity in the reduction of CO2 to CO with water as the sacrificial reductant. Over 3-fold and 6-fold higher activities than those of pristine CsPbBr3 nanocrystals and TiO-CN nanosheets, respectively, were observed under visible light irradiation. Our study provides an effective strategy for improving the photocatalytic activity of metal-halide perovskite nanocrystals, thus promoting their photocatalytic application in the field of artificial photosynthesis.