Pd-catalyzed instant hydrogenation of TiO2 with enhanced photocatalytic performance

Abstract

Hydrogenated TiO₂ with remarkably elevated photocatalytic activity has triggered great interest, which, unfortunately, has been commonly obtained so far under severe conditions such as extraordinarily high pressure (20.0 bar) and/or high temperature (up to 700 °C) over a long period of treatment (up to several days). Here, through doping with a slight amount of Pd, hydrogenated TiO₂ is obtained at room temperature under non-pressurised H₂ or H₂/O₂ gas flow within several minutes. This extremely facile Pd-catalyzed hydrogenation strategy is based on the discovered fact that H₂ could spontaneously dissociate on the Pd surface to generate highly active atomic hydrogen species [H], which would diffuse into and interact with the TiO₂ lattice to generate durable point defects (Ti³⁺, oxygen vacancies) and even surface disorder, resulting in the largely enhanced solar energy utilization of TiO₂. Additionally, the proposed Pd-catalyzed hydrogenation strategy turns out to be applicable to reduce other transition metal oxides, providing a general methodology for oxide hydrogenation under ordinary conditions.