One-pot synthesis of MIL-68(In)-derived CdIn2S4/In2S3 tubular heterojunction for highly selective CO2 photoreduction

The goal of photocatalytic CO₂ reduction is to obtain a single energy-bearing product with high efficiency and stability. Consequently, constructing highly selective photocatalysts with enhanced surface and optoelectronic properties is crucial for achieving this objective. Here, we have developed a simple one-pot vulcanization method to synthesize a MIL-68(In)-derived CdIn₂S₄/In₂S₃ heterojunction that exhibited stable and high selectivity. Multiple characterizations of the CdIn₂S₄/In₂S₃ heterojunction revealed a hierarchical tubular structure with numerous surface reactive sites, a high visible-light utilization rate (λ < 600 nm), efficient charge separation, and a prolonged charge-carrier lifetime. Moreover, an S-scheme charge transfer mechanism, based on the interleaved band between the two components, improved the reduction capability of the electrons. Benefiting from the compositional and structural synergy, the yield CO by CdIn₂S₄/In₂S₃-250 (CI-250) reached 135.62 μmol·g⁻¹·h⁻¹, which was 49.32 times and 32.88 times higher than that of In₂S₃ and CdIn₂S₄, respectively. The CdIn₂S₄/In₂S₃ heterojunction exhibited a quantum efficiency of 4.23% with a CO selectivity of 71%. Four cycle tests confirmed the good stability and recyclability of the CI-250. This work provides a new approach for designing and preparing high-performance hollow MOFs-based photocatalysts for scalable and sustainable CO₂ reduction.