2D-2D heterojunction engineering for enhanced photothermal CO2 reduction: synergistic effect of deprotonation and LSPR on Ultrathin BiOI/Ti3C2 nanosheets

Abstract

Due to the shortage of protons and electrons in carbon dioxide (CO₂) reduction experiments, the current catalytic process is facing efficiency issues. This study synthesized Ti₃C₂ Mxene through etching and ultrasonic exfoliation, and integrated BiOI nanosheets with Ti₃C₂ using solvothermal method to create a 2D/2D BiOI/Ti₃C₂ Schottky heterojunction. The oxygen vacancies in BiOI capture water molecules for deprotonation, providing sufficient protons for photocatalytic CO₂ reduction reactions. Due to the formation of 2D/2D Schottky heterojunctions, utilizing large heterojunction interfaces and short carrier migration paths facilitates charge separation and transfer, thereby improving the charge separation efficiency at heterojunction interfaces. In addition, the localized surface plasmon resonance (LSPR) effect of Ti₃C₂ enhances catalytic activity by promoting the generation of hot electrons and converting light energy into thermal energy, thereby generating a photothermal synergistic effect. Under simulated sunlight, BiOI/Ti₃C₂ nanosheets significantly improved the photocatalytic CO₂ reduction efficiency, producing 4.8 times and 5.3 times more carbon monoxide (CO) than using BiOI and Ti₃C₂ alone. After three cycles of experiments, the catalytic performance of the composite material remains stable, and the loss can be ignored. These findings provide valuable insights into catalyst design for future CO₂ reduction applications.