Rapid fabrication of oxygen-deficient zirconia by flash sintering treatment
Xinghua Su, Wenjin Li, Da Chen, Shuai Zhang, Chengguang Lou, Qiang Tian, Jianguo Zhao, Peng Zhao
Abstract
The introduction of oxygen vacancies into zirconia is an effective strategy for enhancing its light absorption ability and photocatalytic performance. However, the cost-efficient preparation of oxygen-deficient zirconia (ZrO<sub>2−<i>x</i></sub>) remains challenging, which severely limits its broad application. In this study, flash sintering treatment was used to fabricate ZrO<sub>2−<i>x</i></sub> bulk in very short time of 90 s. Oxygen vacancies were introduced into ZrO<sub>2</sub> bulk through electrochemical reduction reactions. The as-prepared black ZrO<sub>2<i>−x</i></sub> exhibited excellent optical absorption capability, a small band gap (2.09 eV for direct and 1.67 eV for indirect), and a reduced conduction band energy, which is ascribed to the generation of oxygen vacancies and reduction of Zr cations. The as-prepared ZrO<sub>2−<i>x</i></sub> showed remarkable photocatalytic activity due to excellent solar light absorption and low recombination rate of electron‒hole pairs. Flash sintering treatment provides a cost-efficient approach for rapidly fabricating ZrO<sub>2−<i>x</i></sub> bulk materials with high concentrations of oxygen vacancies, which can also be applied to other materials.