Enhanced CO₂ Photoreduction over Bi₂Te₃/TiO₂ Nanocomposite via a Seebeck Effect

Abstract

The activation of carbon dioxide (CO2) molecules and separation/transfer of photoinduced charge carriers are two crucial factors influencing the efficiency of CO2 photoreduction. Herein, we report a p-type Bi2Te3/commercial TiO2 (pBT/P25) nanocomposite for enhanced CO2 photoreduction. Upon light irradiation, a temperature gradient formed in pBT induces the Seebeck effect to build a thermoelectric field, which promotes the charge carriers’ separation/transfer. Additionally, pBT with a strong light absorption capacity generates the photothermal effect favoring the activation of CO2 molecules. In addition, the excellent electric conductivity and large work function render pBT an efficient cocatalyst for further improving the charge carriers’ separation/transfer. Owing to the synergistic enhancement effect of pBT on the activation of CO2 molecules and promotion of charge separation/transfer, we achieved the highest CO evolution rate over pBT(2)/P25 of 19.2 μmol·gcat−1·h−1, which was approximately 5.5 times that of bare P25. This work suggests that a thermoelectric material/semiconductor nanocomposite could be developed as an efficient photo-thermo-electro-chemical conversion system for enhanced CO2 reduction via promoting the charge carriers’ separation/transfer.

Keywords

• TiO₂
• Bi₂Te₃
• Seebeck effect
• CO₂ photoreduction
• charge separation