Photonic Crystals Assembled by SiO2@Ni/TiO2 for Photocatalytic Reduction of CO2

Abstract

Photonic crystal (PC) can manipulate light propagation due to the presence of photonic band gap (PBG). PBG can redistribute density of optical state. When the PBG overlaps with the emission of an emitter embedded in PC, the excited electrons will be prohibited from transferring to the ground state. Introducing PC with suitable PBG into photocatalyst will partially reduce the electron–hole combination and improve photocatalytic efficiency. Meanwhile, appropriate specific surface area of 3-D quasi-ordered structure can increase the contact area of catalysts and CO2 to provide more catalytic sites, which plays an important role in the improvement of photocatalytic activity. Herein, SiO2@Ni/TiO2 PCs with designed PBG were fabricated and applied as catalysts for photocatalytic CO2 reduction using [Ru(bpy)3]Cl2·6H2O as photosensitizer. The designed SiO2@Ni/TiO2 PCs has a suitable specific surface area and certain surface roughness, which can effectively adsorb CO2 for photocatalytic reduction. Meanwhile, the PBG of SiO2@Ni/TiO2 PCs matches well with the electron–hole combination energy of the photosensitizer, the electron–hole combination process from the excited state falling back to the ground state can be prevented partially. Suppressing the falling of excited electrons will make electrons transfer to the catalyst, thereby improving the photocatalytic performance.