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-TiO 2 (p-type TiO 2 ) 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/cm 2 ) was achieved over Au/p-TiO 2, which is approximately 5 times as high as that over Au/n-TiO 2 under the same conditions. Photoluminescence and electrochemical impedance spectroscopy measurements indicate enhanced charge carrier separation and transfer for Au/p-TiO 2 . In an elaborate study, apparent quantum efficiency and transmission electron microscopy characterization on selective PbO 2 deposition over p-TiO 2 revealed that visible-light-excited holes other than electrons generated in the Au interband transition transferred to p-TiO 2, which is opposite to the general route in Au/n-TiO 2 (n-type TiO 2 ). 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-TiO 2 . This discovery opens up new opportunities in designing and developing efficient metal semiconductor composite materials with visible-light response.