Flower-like Z-scheme heterostructure of cobalt porphyrin/ZnIn2S4 for boosting photocatalytic solar fuel production

Abstract

Molecular catalysts have attracted significant attention in photocatalytic CO2 reduction (PCR) due to well-defined structure and exceptional catalytic selectivity. However, they are still limited by recycling challenges and inherent instability. Forming an organic-inorganic composite can address these issues and enhance PCR performance simultaneously. Herein, we developed a flower-like Z-scheme heterojunction of cobalt porphyrin ([meso-tetra(4-sulfonatophenyl)porphyrin], CoTPPS) and ZnIn2S4 (ZIS). The optimized ZIS@CoTPPS exhibited a superior CO evolution rate of 388.26 μmol g−1 h−1, which is 8.96 times of pristine ZIS (43.32 μmol g−1 h−1). The superior PCR activity is contributed by the enhanced light absorption, and photoinduced charge separation facilitated by the Z-scheme structure and the cobalt active sites. Moreover, theoretical calculations confirm the heterojunction relies on a substantial interfacial coupling between the Zn atoms of ZIS and the sulfonic acid groups of CoTPPS through coordination assembly. This investigation affords a useful inspiration for consciously constructing novel ZIS-incorporated atomistic Z-scheme photocatalysts.