Photocatalytic reduction of CO2 over platinised Bi2WO6-based materials

Abstract

The photocatalytic reduction of CO₂ with H₂O to produce CH₄ in the gas phase was carried out in the presence of two Bi₂WO₆-based materials. For this purpose, single Bi₂WO₆ and a coupled Bi₂WO₆–TiO₂ system were synthesised and metallised with Pt, through a Pt photodeposition method. Then, the samples were characterised and the photocatalytic activity was evaluated in a continuous fluidised-bed reactor irradiated with UV light. Single Bi₂WO₆ presents an interesting behaviour under H₂O rich conditions. In particular, the metallisation improves the material's performance for CH₄ formation, while the TiO₂ addition to Bi₂WO₆ increases the CH₄ yield only at low H₂O/CO₂ ratio. The Bi₂WO₆–TiO₂ system metallised with a Pt photocatalyst displayed the highest CH₄ yield among all the prepared photocatalysts. The stability of the system can be enhanced through the addition of a blue phosphor to the reactant mixture, especially under H₂O rich conditions.