Improved charge separation and carbon dioxide photoreduction performance of surface oxygen vacancy-enriched zinc ferrite@titanium dioxide hollow nanospheres with spatially separated cocatalysts.

Here, we describe the fabrication of surface oxygen vacancy-enriched ZnFeO@TiO double-shell hollow heterostructure nanospheres (ZnFeO@H-TiO) coupled with spatially separated CoO and Au-Cu bimetallic cocatalysts. The ZnFeO@TiO heterojunction and spatially separated dual cocatalysts can significantly promote the separation of photoinduced charge carriers. Combined with the unique hollow double-shell heterostructure characteristics and improved surface state properties, the hybrid nanospheres can efficiently adsorb and activate CO molecules. These advantages cause the optimized catalyst to exhibit remarkably higher gas-phase photocatalytic CO reduction activity than the control CoO/ZnFeO/Au-Cu and ZnFeO@H-TiO double-shell hollow nanospheres loaded with a single cocatalyst. Meanwhile, the Au-Cu bimetal effect boosts the CO conversion rate and CH selectivity. The optimized hybrid catalyst with a Au/Cu ratio of 1:1 provides a CH yield of 21.39 μmol g h with 93.8% selectivity. This work provides a rational photocatalyst design to improve CO conversion and CH selectivity.