Bi quantum dots obtained via in situ photodeposition method as a new photocatalytic CO2 reduction cocatalyst instead of noble metals: Borrowing redox conversion between Bi2O3 and Bi

Scientific Achievement

Bi quantum dot is applied as the cocatalyst instead of noble metals, for the first time, in photocatalytic CO₂ reduction and exhibits significant increase in CO yield compared to that of pristine photocatalyst, about 4.8 times. Such small Bi is unstable in air, making it very difficult for the preservation. We found the unstable metal Bi can be stored via using the form of Bi/Bi₂O₃ quantum dots (Bi₂O₃ is main body of white Bi/Bi₂O₃ composites). When carried out the photocatalytic CO₂ reduction, the white Bi/Bi₂O₃ can be easily transformed into grey Bi/Bi₂O₃ composites (the main body of grey Bi/Bi₂O₃ composites is metal Bi) to improve the photocatalytic CO₂ reduction rate. This reason is that CB level of Bi₂O₃ quantum dots has shifted to a more negative position due to quantum confinement effect compared to the standard redox potential of Bi₂O₃/Bi (0.37eV), leading to Bi₂O₃ easily to be reduced to metal Bi under the effect of photogenerated electrons derived from TiO₂.

Significance and Impact

This work demonstrated the mutual conversion between storage and utilization may offer an attractive approach for the application of unstable quantum dot materials or single atom materials.

Research Details

The TiO₂/Bi/ Bi₂O₃ composites photocatalysts were prepared via using in-situ photodeposition methods;

The prepared samples were characterized by SEM, TEM, DSR, XPS, PL and so on;

The CO₂ photo-reduction activities of samples were performed via the photocatalytic system.