Acetate-assistant efficient cation-exchange of halide perovskite nanocrystals to boost the photocatalytic CO2 reduction

The judicious implantation of active metal cations into the surface of semiconductor nanocrystal (NC) through cation-exchange is one of the facile and viable strategies to enhance the activity of catalysts for photocatalytic CO2 reduction, by shortening the transfer pathway of photogenerated carriers and increasing the active sites simultaneously. However, cation-exchange is hard to achieve for halide perovskite NCs owing to the stable octahedron of [PbX6](4-) with strong interaction between halogen and lead. Herein, we report a facile method to overcome this obstacle by replacing partial Br- with acetate (Ac-) to generate CsPbBr3 NC (coded as CsPbBr3-xAcx). A small amount of Ac- instead of Br- does not change the crystal structure of halide perovskite. Owing to the weaker interaction between acetate and lead in comparison with bromide, the corresponding octahedron structure containing acetate in CsPbBr3-xAcx can be easily opened to realize efficient cation-exchange with Ni2+ ions. The resulting high loading amount of Ni2+ as active site endows CsPbBr3-xAcx with an improved performance for photocatalytic CO2 reduction under visible light irradiation, exhibiting a significantly increased CO yield of 44.09 mu mol.g(-1)h(-1), which is over 8 and 3 times higher than those of traditional pristine CsPbBr3 and nickel doped CsPbBr3 NC, respectively. This work provides a critical solution for the efficient metal doping of low-cost halide perovskite NCs to enhance their photocatalytic activity, promoting their practical applications in the field of photocatalysis.

Automated summary

The study presents a new method to enhance the photocatalytic activity of halide perovskite nanocrystals by partially replacing bromide ions with acetate to facilitate cation-exchange, resulting in improved CO2 reduction performance under visible light irradiation. CsPbBr3-xAcx exhibits a significantly increased CO yield compared to traditional CsPbBr3 and nickel-doped CsPbBr3 NC under visible light.