Oxygen-Defective Ultrathin BiVO₄ Nanosheets for Enhanced Gas Sensing

BiVO₄ nanomaterials are potentially applicable in gas sensing, but the sensing performance is limited by the less active sites on the BiVO₄ surface. In this work, we propose a strategy to improve the gas-sensing performance of BiVO₄ by forming ultrathin nanosheets and introducing oxygen vacancies, which increase the surface active sites. Two-dimensional (2D) BiVO₄ nanosheets with oxygen vacancies are prepared through a colloidal method with the assistance of nitric acid. Gas sensors based on the oxygen-defective 2D ultrathin BiVO₄ nanosheets exhibit an enhanced sensing response, which is 3.4 times higher than those of the sensors based on oxygen-abundant BiVO₄ nanosheets. The density functional theory calculation is employed to uncover the promoting effects of oxygen vacancies on enhancing the O₂ adsorption capability of BiVO₄ nanosheets. This work is not only expected to build a wide range of 2D metal oxide semiconductors with a high gas-sensing performance but also gives an insight into the mechanism of the enhanced response induced by the oxygen vacancies, which will be a guideline for further designing high-performance sensing materials.