Artificial Photosynthesis of C4 Hydrocarbon on Dual-Vacancy Copper–Indium Sulfide

Abstract

Isobutane (C4H10) is an important raw material for the synthesis of various industrial products, including hydrocarbon refrigerants, alkylated gasoline, and propylene oxide. Conventionally, it is produced via catalytic cracking under harsh conditions, typically at temperatures of 423–673 K and pressures of 2.0–4.0 MPa. In this study, we report a novel approach for converting CO2 into C4H10 under ambient pressure. Our method employs a mild photocatalytic route, achieving an impressive production rate of 33.57 μmol·g–1·h–1 with a remarkable selectivity of 96.17%. During photocatalytic CO2 reduction in aqueous solution, the CuInS2 (CIS) nanoflower catalyst undergoes in situ reconstruction, transforming into a CuInS2/In(OH)3 (CIS/IOH) composite featuring both sulfur (Sv) and indium (Inv) vacancies. These vacancies within the CIS/IOH structure significantly enhance asymmetric charge distribution at the dual metal sites, stabilize key reaction intermediates, and reduce the energy barrier for C–C coupling, thereby facilitating the hydrogenation process that leads to the formation of C4H10. This work presents an artificial photosynthesis strategy for selectively producing high-purity C4H10 with low production cost under mild reaction conditions, aligning with the principles of green chemistry and low energy consumption.