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

Abstract

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 μmol 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.