Fabrication of inverse opal TiO2-supported Au@CdS core-shell nanoparticles for efficient photocatalytic CO2 conversion

The photocatalytic conversion of CO2 with H2O into renewable hydrocarbon fuels by solar energy is of significance in solving both energy and environmental problems. Herein, we firstly report a practical fabrication of all-solid-state three-component Z-scheme system with the core-shell structured Au@CdS core-shell nanoparticles on inverse opal TiO2 (Au@CdS/IO-TiO2) via the gas bubbling-assisted membrane reduction-precipitation (GBMR/P) method. All the catalysts possess well-defined inverse opal structure with the interconnected networks of spherical voids, and the Au@CdS core-shell nanoparticles with different molar ratios of Cd/Au are well dispersed and supported on the inner wall of uniform macropore. The slow photon effect of inverse opal structure with moderate macropore sizes can enhance the light-harvesting efficiency. And the all-solid-state Z-scheme system with CdS(shell)-Au(core)-TiO2(support) nanojunction is favourable for the separation of photogenerated electrons and holes due to the vectorial electron transfer of TiO2 -> Au -> CdS. The Au@CdS/IO-TiO2 catalysts exhibit super photocatalytic performance for CO2 reduction to CH4 under the simulated solar irradiation. Among the as-prepared catalysts, Au@CdS/IO-TiO2-1 catalyst with the moderate thickness of CdS nanolayer shell shows the highest photocatalytic activity and selectivity for CO2 reduction, e.g., its formation rate of CH4 is 41.6 mu mol g(-1) h(-1) and its selectivity to CH4 production by CO2 reduction is 98.6%. The design and versatile synthetic approach of all-solid-state Z-scheme system on the surface of inverse opal oxides are expected to throw new light on the fabrication of highly efficient photocatalyst for CO2 reduction to hydrocarbon. Crown Copyright (C) 2015 Published by Elsevier B.V. All rights reserved.