CsPbBr3/CdSe Heterostructures for Photocatalytic CO2 Reduction

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Converting CO2 into chemical fuels using sunlight is a promising approach towards addressing the increasing levels of greenhouse gases while reducing our reliance on fossil fuels. Among the many identified photocatalysts to achieve this, metal halide perovskite nanocrystals are a prospective class due to their favourable optoelectronic and structural properties. However, the rapid and efficient radiative recombination, as well as limited CO2 activation by such pristine perovskite nanocrystals, hinders their photocatalytic efficiency. Herein, a ligand-engineering approach is harnessed to develop 0D CsPbBr3 nanocrystal – 2D CdSe nanoplatelet heterostructures to enhance photo-induced carrier separation and improve photocatalytic activity. This is demonstrated through photocurrent and CO2 reduction studies, which yield up to 8-fold-enhancements in CO and CH4 production yields relative to the pristine nanocrystals. Detailed characterisation of these heterostructures suggests that their photocatalytic properties are enabled by a staggered energy level alignment at the CdSe and CsPbBr3 interface, which promotes a built-in electric field of up to 0.5 eV. Electron spin resonance measurements further suggests that the heterojunction operates through a direct Z-scheme mechanism. This work highlights the potential of ligand-assisted heterojunction design in perovskite-based photocatalysts, providing a valuable platform for enhancing solar-to-chemical conversion efficiency.