Construction of 2D Bismuth Silicate Heterojunctions from Natural Mineral toward Cost-Effective Photocatalytic Reduction of CO2

Photocatalytic reduction of carbon dioxide to chemical fuels is an attractive route to generate renewable energy and curtail the green house effect. However, it remains a great challenge to explore cost-effective photocatalysts using natural and readily available clay minerals. In this work, one-dimensional natural palygorskite (Pal) is treated with acid to remove most of the metal ions from the silica framework, and bismuth ions are incorporated to grow two-dimensional (2D) bismuth silicate (Bi12SiO20) nanosheet under a microwave-hydrothermal process. Excess Bi ions generate bismuth oxide (BiO2-x) nanoparticles that respond to near infrared (NIR) light and coprecipitate on the surface of Bi12SiO20, which forms a well-defined S-scheme Bi12SiO20/BiO2-x heterojunction facilitating the charge transfer and maintaining high redox potentials. The abundant active sites on the 2D Bi12SiO20 sheet and the oxygen vacancies in BiO2-x particles are found to favor the cooperative activation and adsorption of CO2. The influence of various amounts of BiO2-x on CO2 reduction performance is explored. Bi12SiO20/BiO2-x-30 wt % shows the best photocatalytic reaction rate at 31.16 mu molmiddotg-1middoth-1 for CH3OH formation during sunlight irradiation. In NIR light, the Bi12SiO20/ BiO2-x-30 wt % even achieves a CH3OH generation rate of 17.1 mu molmiddotg-1middoth-1. The current study potentially provides a sustainable approach for CO2 conversion.