Balancing the piezoelectric coefficient and carrier concentration of Bi <sub>2</sub>WO <sub>6− <i>x</i> </sub> for ultrahigh piezocatalysis
Ying Wang, Xiaoli Xu, Lingbo Xiao, L Li, Qiuhua Xu, Zhenhai Wen, Laishun Qin, Yanmin Jia, Dong‐Liang Peng, Wanping Chen, Da Chen
Abstract
Balancing the piezoelectric coefficient and carrier concentration of materials is key in the field of piezocatalysis. In this work, Bi<sub>2</sub>WO<sub>6</sub> material with both piezoelectric and semiconductor properties was chosen as a model material. A one-step ethylene glycol (EG)-assisted solvothermal method was used to synthesize Bi<sub>2</sub>WO<sub>6</sub> with oxygen vacancies. By controlling the solvothermal time and temperature, the oxygen vacancy concentration (<i>C</i><sub>OV</sub>) was regulated. As <i>C</i><sub>OV</sub> increases, the piezoelectric coefficient decreases, the carrier concentration increases, and the hydrogen production rate first increases but then decreases. When <i>C</i><sub>OV</sub> reaches 1.45×10<sup>12</sup> spins·mg<sup>−1</sup>, the corresponding piezoelectric coefficient and carrier concentration are 13.9 pm·V<sup>−1</sup> and 2.90×10<sup>20</sup> cm<sup>−3</sup>, respectively. The optimal hydrogen production rate per power of 2.21 μmol·g<sup>−1</sup>·h<sup>−1</sup>·W<sup>−1</sup> is equivalent to or even better than that of most reported piezocatalysts. The piezoelectric coefficient and carrier concentration, as two factors, jointly determine the piezocatalytic performance. The findings of this research can provide important and deep-seated insights for better piezocatalysts in the future.