Creating Cation Vacancies in BiOCl Nanosheets Toward Exceptional Visible‐Light‐Driven Photocatalytic CO2 Reduction

Abstract BiOCl‐based materials have emerged as promising photocatalysts for converting CO 2 into valuable products and fuels. However, challenges such as low light absorption and inefficient charge carrier separation require effective solutions, with vacancy engineering offering a promising approach. Current research primarily focuses on anion vacancies, leaving cation vacancies less explored. In contrast, this study presents a novel method to enhance visible‐light‐driven photocatalysts by Bi cation vacancies in ultrathin BiOCl nanosheets through a straightforward hydrochloric acid etching process (HAE‐BiOCl). These introduced Bi vacancies not only expand the light absorption range and enhance carrier separation, but also serve as active sites for CO 2 adsorption. Additionally, Bi vacancies can effectively lower the activation energy of COOH − species and thereby enhance overall reaction activity. As a result, the HAE‐BiOCl catalyst exhibits exceptional photocatalytic CO 2 reduction performance without the need for co‐catalysts or sacrificial agents. It achieves high CO generation rates of 68.39 and 17.43 µmol g −1 h −1 under 300 W Xe lamp and visible light irradiation, respectively. These rates are significantly higher compared to counterparts without vacancy creation and surpass those of most reported Bi‐based photocatalysts. This study underscores the potential of inducing cation vacancies via acid etching as a valuable strategy for advancing photocatalysis.