No abstract

No abstract

We examine in detail the roles of Ti 3+ defects and the associated oxygen vacancies in the activity and selectivity of TiO 2 -supported Au catalysts (Au@TiO 2 ) for renewable hydrogen production by photoreforming of ethanol. A series of Au@TiO 2 catalysts was synthesized using varied exposure to reducing agent NaBH 4 . The electronic structure of the series of Au@TiO 2 catalysts was examined spectroscopically and showed that increased exposure to NaBH 4 increased the concentration of Ti 3+ defects and the associated oxygen vacancies in TiO 2 , and increased the amount of electron-rich Au. The activity and selectivity of the catalysts increased as the concentration of defect sites increased. During ethanol photoreforming, the Au@TiO 2 catalyst with the highest concentration of defects produced highpurity H 2 at a record rate of ∼7093 μmol g cat −1 h −1 and the carbon−carbon bond (C−C) cleavage of ethanol to form CH 4 and CO 2 was significantly inhibited. Extensive spectroscopic data support the conclusion that TiO 2 surface oxygen vacancies adjacent to Au may be active catalytic sites that assist the adsorption and activation of ethanol as well as the delivery of photogenerated charge carriers to the activated species during the photoreforming of ethanol.

No abstract

The photo-driven oxidation of organic molecules into corresponding high-value-added products has become a promising method in chemical synthesis. This strategy can drive thermodynamically non-spontaneous reactions and achieve challenging thermocatalytic processes under ambient conditions. Reactive oxygen species (ROS) are not only significant intermediates for producing target products via photoinduced oxidation reactions but also contribute to the creation of sustainable chemical processes. Here, the latest advances in heterogeneous photo-driven oxidation reactions involving ROS are summarized. The major types of ROS and their generation are introduced, and the behaviors of various ROS involved in photo-driven processes are reviewed in terms of the formation of different bonds. Emphasis is placed on unraveling the reaction mechanisms of ROS and establishing strategies for their regulation, and the remaining challenges and perspectives are summarized and analyzed. This Review is expected to provide an in-depth understanding of the mechanisms of ROS involved in photo-driven oxidation processes as an important foundation for the design of efficient catalysts. Clarifying the role of ROS in oxidation reactions has important scientific significance for improving the atomic and energy efficiency of reactions in practical applications.