Aspect ratio dependent photocatalytic enhancement of CsPbBr3 in CO2 reduction with two-dimensional metal organic framework as a cocatalyst

All-inorganic CsPbBr3 perovskites have been regarded as promising candidates for photocatalytic CO2 reduction, but the conversion efficiency is limited by serious charge recombination and poor surface reactivity. Herein, a two-dimensional Ni based metal-organic framework (NMF) has been employed as a cocatalyst, which not only acts as an electron extractor in enhancing the electron-hole separation, but also serves as a CO2 capturing agent in facilitating the adsorption and activation of CO2 molecules. As a result, 1.8, 2.5 and 4.1-fold enhancement in CO production has been realized for CsPbBr3 nanocubes, nanorods and nanowires, respectively, which is proved to be positively correlated with the aspect ratio of CsPbBr3. The aspect ratio dependent photocatalytic enhancement is attributed to the increased energy difference at the interface between the conduction band of CsPbBr3 and NMF with the elongation of CsPbBr3, which produces an enlarged driving force for promoted interfacial electron transfer and superior charge separation properties.