Remarkable Visible-Light Photocatalytic Activity Enhancement over Au/p-type TiO₂ Promoted by Efficient Interfacial Charge Transfer

Metal-induced photocatalysis has emerged as a promising approach for exploiting visible-light-responsive composite materials for solar energy conversion, which is generally hindered by low photocatalytic efficiency. Herein, for the first time, an Au/p-TiO₂ (p-type TiO₂) strategy with the hole transfer mechanism is developed, remarkably promoting visible-light photocatalytic performance. An efficient acetone evolution rate (138 μmol·g^-1·h^-1) in the photocatalytic isopropyl alcohol (IPA) degradation under λ_ex = 500 nm light (light intensity, 5.5 mW/cm²) was achieved over Au/p-TiO₂, which is approximately 5 times as high as that over Au/n-TiO₂ under the same conditions. Photoluminescence and electrochemical impedance spectroscopy measurements indicate enhanced charge carrier separation and transfer for Au/p-TiO₂. In an elaborate study, apparent quantum efficiency and transmission electron microscopy characterization on selective PbO₂ deposition over p-TiO₂ revealed that visible-light-excited holes other than electrons generated in the Au interband transition transferred to p-TiO₂, which is opposite to the general route in Au/n-TiO₂ (n-type TiO₂). Energetic holes generated in the d band of Au led to a fluent transfer across the Schottky barrier, which is further confirmed by the IPA photodegradation mechanism study with different scavengers over Au/p-TiO₂. This discovery opens up new opportunities in designing and developing efficient metal semiconductor composite materials with visible-light response.