Oxygen-Defective\nUltrathin BiVO₄ Nanosheets\nfor Enhanced Gas Sensing

Abstract

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