Supercritical CO2-Tailored Topological Transfer from CuTCNQ II to CuTCNQ I for Enhanced Photocatalytic CO2 Reduction

Abstract

Photocatalytic CO2 reduction offers a promising approach for sustainable conversion of greenhouse gas into chemical fuels. However, the activity is severely limited by the rapid charge recombination in photocatalytic systems. Since precise atomic modulation is an effective approach to suppress charge recombination, metal–organic frameworks (MOFs) are considered to be ideal platforms for achieving efficient photocatalytic CO2 reduction. By utilizing the solvent effect and stress engineering of supercritical carbon dioxide (SC CO2), the structure of a typical charge transfer MOF, CuTCNQ, was precisely tailored, leading to the conversion from thermodynamically stable phase II to kinetically stable phase I. The SC CO2-tailored CuTCNQ exhibits significantly enhanced photocatalytic activity toward CO2 reduction under aqueous conditions, accompanied by the formation of a desirable amount of C2 products (342.1 μmol gCu–1 h–1 with 47.5% for C2 selectivity). In addition to facilitated charge transfer, the substantial activity enhancement is attributed to the extended exciton lifetime based on transient absorption spectroscopy.