Air promotes efficient and selective CO2 photoreduction with a molecule/semiconductor hybrid photocatalyst: the significant role of simultaneous photodegradation of organic pollutants

The photoreduction of CO2 with atmospheric air represents a promising avenue toward the sustainable utilization of CO2. Herein, a noble-metal free molecule/semiconductor hybrid photocatalyst has been employed for the first time for converting CO2 to CO with 100% selectivity in water and simultaneous photodegradation of tetracycline in the presence of air. The hybrid photocatalyst consists of carbon nitride and a molecular Ni(ii)–terpyridine complex, which shows an order of magnitude improvement in CO yield when exposed to a mixed CO2/air atmosphere compared to high-purity CO2 conditions. The CO yield is up to 623.3 μmol g−1, among the highest for CO2 photoreduction in the presence of air. Our findings reveal that the simultaneous photodegradation of tetracycline is vital for the enhanced yield of CO in the presence of air. The photodegradation process consumes more photogenerated holes, aided by reactive oxygen species, which further optimizes the separation of photogenerated electron–hole pairs. Consequently, photogenerated electrons in the conduction band migrate more efficiently to the linked Ni(ii)–terpyridine moiety, leading to improved CO2 photoreduction efficiency. Notably, the presence of air does not inhibit but actually promotes the photoreduction of CO2. This study provides a unique strategy in which photocatalytic removal of organic pollutants is integrated with high-performance CO2 photoreduction with the aid of air.