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

Abstract

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.