Platinum Nanoparticles Supported on TiO2 Photonic Crystals as Highly Active Photocatalyst for the Reduction of CO2 in the Presence of Water

Abstract

Photonic crystals can delay the propagation of light and increase its path length through a slow-light effect, which could have immense potential in improving photocatalytic conversion efficiencies. We employed a colloidal crystal template method to synthesize TiO2 photonic crystals (PC-TiO2), with platinum nanoparticles (Pt NPs) being deposited on the surface of the PC-TiO2 support at different loading amounts by the gas bubbling-assisted membrane reduction (GBMR) method. A series of Pt/PC-TiO2 photocatalysts with well-defined inverse-opal structure have uniform Pt NPs (about 2.5 nm) homogeneously dispersed on the pore walls of the support. The slow-light effect of photonic crystals effectively enhances the absorption efficiency of solar irradiation. Moreover, the Pt deposition significantly extends the spectral response and reduces the recombination rates of photoinduced electron–hole pairs. As a result, the Ptx/PC-TiO2 catalysts exhibit excellent photocatalytic activity for the reduction of CO2 in the presence of H2O. In addition, we propose a reaction mechanism for the photoreduction of CO2 under light irradiation.