3D homogeneous porous copper-ceria catalyst for solar light driven photothermal CO-PROX in H2-rich gas: Enhanced light absorption and abundant oxygen vacancy

Photothermal preferential oxidation of CO (CO-PROX) on copper-ceria catalyst has emerged as an efficient and energy-saving approach for trace CO purification in hydrogen-rich gas. However, the limited light absorption and photo-to-thermal conversion capability of the copper-ceria catalyst hinder its catalytic performance for photothermal CO-PROX. In this study, a three-dimensional homogeneous porous copper-ceria catalyst (3DHP) was developed by using ordered SiO2 microspheres as the hard template. Compared to 3DIP catalyst with disordered silica colloid as the template, the uniform 3D pore structure, smaller particle size and abundant oxygen vacancy in 3DHP remarkably promote its photothermal catalytic performance for CO-PROX driven by the simulated solar light. The uniform 3D pore structure of 3DHP catalyst greatly strengthens the light absorption and photo-to-thermal conversion ability due to the slow photon effect of photonic crystals, which obtained higher surface temperature under the light irradiation. The higher specific surface area contributed to the high dispersion of copper species on 3DHP catalyst. Additionally, the more abundant oxygen vacancy facilitated the activation of O2 and the efficient electron-hole separation in 3DHP catalyst. Moreover, the visible light contributes to the largest portion of the total CO conversion due to the strong absorption ability of 3DHP in this range.