3D ordered macroporous TiO2-supported Pt@CdS core-shell nanoparticles: design, synthesis and efficient photocatalytic conversion of CO2 with water to methane

A series of photocatalysts of three-dimensionally ordered macroporous (3DOM) TiO2-supported core-shell structured Pt@CdS nanoparticles were facilely synthesized by the gas bubbling-assisted membrane reduction-precipitation (GBMR/P) method. All the catalysts possess a well-defined 3DOM structure with interconnected networks of spherical voids, and the Pt@CdS core-shell nanoparticles with different molar ratios of Cd/Pt are well dispersed and supported on the inner wall of uniform macropores. The 3DOM structure can enhance the light-harvesting efficiency due to the increase of the distance of the light path by enhancing random light scattering. And the all-solid-state Z-scheme system with a CdS(shell)-Pt(core)-TiO2(support) nanojunction is favourable for the separation of photogenerated electrons and holes because of the vectorial electron transfer of TiO2 -> Pt -> CdS. 3DOM Pt@CdS/TiO2 catalysts exhibit super photocatalytic performance for CO2 reduction to CH4 under simulated solar irradiation. Among the as-prepared catalysts, the 3DOM Pt@CdS/TiO2-1 catalyst with the moderate thickness of a CdS nanolayer shell shows the highest photocatalytic activity and selectivity for CO2 reduction, e.g., its formation rate of CH4 is 36.8 mmol g(-1) h(-1) and its selectivity for CH4 production by CO2 reduction is 98.1%. The design and versatile synthetic approach of the all-solid-state Z-scheme system on the surface of 3DOM oxides are expected to throw new light on the fabrication of highly efficient photocatalysts for CO2 reduction to hydrocarbon.