Modulation of oxygen vacancy in hydrangea-like ceria via Zr doping for CO2 photoreduction

Abstract

The defects like oxygen vacancy in a photocatalyst are critical factors to influence the photocatalytic reactivity since they can have an impact on the behavior of photogenerated charge carrier. Since oxygen vacancy can be readily formed in the ceria due to reversible conversion of the oxidation states between Ce4+ and Ce3+, here ceria is used as the target material. A versatile and facile co-precipitation method was adopted to synthesize hydrangea-like Ce1−xZrxO2 (x = 0.00, 0.025, 0.05 and 0.10). The amount of oxygen vacancy in the obtained catalysts can be modulated by altering the molar fraction of doped Zr. The composition, morphology, physico-chemical properties of the as-synthesized Ce1−xZrxO2 were characterized by using different techniques. It is found that Zr doping into the ceria crystal lattice can lead not only to an enhanced specific surface area and surface adsorption capacity for CO2, but also to an increased concentration of oxygen vacancy that can exist in the bulk and on the surface. The Zr-doped ceria exhibits an enhanced activity for photoreduction of CO2, which can be explained based on the influence mechanism of oxygen vacancy. This work shows that the oxygen vacancy in the ceria can be modulated via a feasible Zr doping approach, which may help design the photocatalysts with high activity for CO2 photoreduction.