Chemically bonded interface construction of the covalent organic framework/CsPbBr3 heterojunction for efficient photocatalytic CO2 reduction driven by visible light†

Abstract

Effective interface interaction is a key factor in enhancing photocatalytic performance due to rapid interfacial charge transport. However, the complex organic synthesis environment and abundance of surface ligands on most metal halide perovskite nanocrystals (MHP NCs) hinder the realization of strong interface interactions and rapid carrier transfer. Herein, a unique covalent organic framework (COF, TpBpy)/CsPbBr₃ catalyst constructed by in situ growth of CsPbBr₃ NCs on a COF in hydrobromic acid (HBr) solvent is formed with a chemical bond (Pb–N coordination) to enhance the CO₂ photoreduction performance. The chemically bonded interface facilitates the transport of photoelectrons from CsPbBr₃ NCs to TpBpy through the Pb–N bond, forming the TpBpy/CsPbBr₃ heterojunction with strong interface interaction and enabling effective separation of photoexcited electron–hole pairs. As a result, the photocatalytic efficiency of the TpBpy/CsPbBr₃ heterojunction reaches up to 239.46 μmol g⁻¹ h⁻¹ (CO) with a high selectivity of 99.66% under visible light irradiation, which is significantly higher than that of pure TpBpy (24.68 μmol g⁻¹ h⁻¹, 97.45%) and CsPbBr₃ NCs (12.58 μmol g⁻¹ h⁻¹, 97.19%), and superior to previous reports on COF/perovskite heterojunctions. This work demonstrates a promising strategy for construction of a COF/MHP heterojunction with strong interface interaction, which has great potential for various optoelectronic applications.