A review of nanostructured non-titania photocatalysts and hole scavenging agents for CO₂ photoreduction processes

The imperative for the development of sustainable energy technologies to alleviate the heavy reliance on fossil fuels as well as to mitigate the serious environmental issues associated with CO₂ emission has fostered the development of solar fuels through CO₂ photoreduction. The well-documented TiO₂ and modified TiO₂-based photocatalysts have been shown to photoreduce CO₂ into hydrocarbons. Meanwhile, there is also an increasing interest in the utilisation of non-titania based materials, namely metal sulphides, oxides, oxynitrides and nitrides, for CO₂ photoreduction. Distinct from other published reviews, we discuss here recent progress made in designing metal sulphide, oxide, oxynitride and nitride photocatalysts for CO₂ photoreduction through morphological changes, aiming at providing a systematic summary of non-titania based materials for CO₂ photoreduction. Furthermore, the introduction of hole scavengers in order to maximise the CO₂ photoreduction efficiency is also reviewed.