Enhanced Adsorption Mediates Efficient CO<sub>2</sub> Reduction over a Ru/TiO<sub>2–<i>x</i></sub> Schottky Heterojunction
Yafei Zheng, S. Ling, Yujing Lv, Ying Wang, Tang Ke, Zhengxin Ding, Jinlin Long
Abstract
Photocatalytic reduction of CO 2 offers a sustainable pathway toward the advancement of renewable energy and the resolution of environmental issues. The adsorption and activation of nonpolar CO 2 molecules play a crucial role in the initial step of CO 2 reduction for most semiconductor materials, making it a challenging task to design active sites on catalyst surfaces that can enhance CO 2 adsorption. Herein, we propose oxygen vacancy (Vo)-regulated Ru/TiO 2– x Schottky heterojunction nanomaterials with exceptional CO 2 adsorption capacity and superior electron–hole separation ability as an advanced photocatalyst suitable for the photocatalytic reduction of CO 2 with water. The incorporation of Vo to increase the physical adsorption capacity of CO 2 by modulating catalyst surface charges, followed by constructing a Ru/TiO 2– x Schottky heterojunction with Ru, further enhances chemisorption and activates CO 2 while simultaneously improving water activation. Particularly, the incorporation of Ru in the form of Ru–O 2– pairs serves as a catalyst for medium basic sites, attracting acidic CO 2 molecules and thereby enhancing the chemical adsorption and dissociation capacity of CO 2 on Ru/TiO 2– x . Furthermore, the Schottky heterojunction induces directional migration of photogenerated electrons, facilitating the efficient separation of photogenerated charges and enhancing the utilization of photogenerated carriers. The synergistic interplay between Vo and metal Ru loading amplifies the photocatalytic performance of the Ru/TiO 2– x catalyst, culminating in a remarkable CO generation rate of 224.6 μmol·g –1 ·h –1 under simulated sunlight irradiation, with an impressive selectivity of 81.6%. This study provides a novel strategy for preparing high-performance photocatalysts by the integration of bifunctional sites, aiming to enhance the CO 2 adsorption efficiency in CO 2 reduction.