Interfacial engineering of Bi2WO6/Fe-substituted palygorskite with a dual Z-scheme heterostructure for efficient and selective photocatalytic CO2-to-CO conversion

Fe ions were incorporated into octahedral sites of palygorskite to achieve lattice reconstruction via a facile hydrothermal route. • A dual Z-scheme heterojunction was constructed in Bi 2 WO 6 /Fe-substituted palygorskite composites for efficient charge separation. • In-situ formed Fe 2 O 3 nanoparticles enhanced visible-light absorption and provided abundant active sites for CO 2 adsorption and activation. • The optimized photocatalyst showed a CO generation rate of 831.26 μmol g −1 h −1 with high selectivity up to 74.82% toward CO. The rational utilization of natural nano-minerals toward high-performance photocatalysts is highly desirable yet challenging. In this work, Fe ions were introduced into the octahedral sites of acid-activated palygorskite (Pal) to realize lattice reconstruction via a thermostatic oil bath-assisted hydrothermal strategy. Bi 2 WO 6 /Fe-substituted Pal (BWO/Fe-Pal) composites were then fabricated by hydrothermal deposition of Bi 2 WO 6 nanosheets on Fe-Pal supports. Fe substitution preserved the basic crystalline structure of Pal while effectively narrowing its band gap. When the Fe mass ratio exceeded 20 wt%, Fe 2 O 3 nanoparticles were in-situ precipitated on Pal surfaces, which strengthened visible-light absorption and provided abundant active sites for synergistic adsorption and photoactivation of CO 2 . The optimized 30FPB-0.3 photocatalyst exhibited a CO generation rate of 831.26 μmol g −1 h −1 , approximately 26.12 times higher than that of pure Bi 2 WO 6 (31.82 μmol g −1 h −1 ). Meanwhile, CO selectivity was significantly improved from 17.6% to 74.82%. Systematic characterizations demonstrated that Fe doping and in-situ formed Fe 2 O 3 modulated the band structure of Pal and increased surface-active sites. Moreover, the hybridization with Bi 2 WO 6 induced the formation of a dual Z-scheme heterojunction, which broadened the photoresponse range and greatly promoted the separation and migration of photogenerated charge carriers. This study provides a green, low-cost, and feasible route for designing efficient mineral-based photocatalysts toward photocatalytic CO 2 reduction. Download: Download high-res image (374KB) Download: Download full-size image