Drastic improvement in the photocatalytic activity of Ga2O3 modified with Mg–Al layered double hydroxide for the conversion of CO2 in water

Abstract

Photocatalytic conversion of CO₂ to useful chemicals is a promising countermeasure against increasing concentrations of CO₂ in the atmosphere as photocatalytic reactions can drive a thermodynamically uphill reaction (so-called “artificial photosynthesis”). Our group has earlier reported that Ga₂O₃ photocatalysts loaded with a Ag cocatalyst exhibit high activity for the conversion of CO₂ to CO in water, and further modification of the catalysts with ZnGa₂O₄ improves the selectivity for CO over the other reduction products by suppressing H₂. In this study, Ga₂O₃ modified with a Mg–Al layered double hydroxide (LDH) considerably enhanced not only the amount of CO evolved but also the selectivity toward CO evolution. By using 1.0 g of a Mg–Al LDH/Ga₂O₃ composite photocatalyst loaded with 0.25 wt% of a Ag cocatalyst, the CO formation rate and selectivity for CO were 211.7 μmol h⁻¹ and 61.7%, respectively. Moreover, the turnover number (TON) of electrons utilized to reduce CO₂ to CO was 75.4 per Ag atom during 5 h of photoirradiation.