Published online by Cambridge University Press: 28 December 2018
In this study, non-cadmium-based quantum dots were synthesized and used as catalysts for the photochemical reduction of bicarbonate to value-added formic acid. Three types of quantum dots (CuS, CuInS2, and CuInS2/ZnS) were chosen because of they feature environmentally benign properties, possess wide optical absorption, and exhibit excellent photocatalytic activity. All three photocatalysts exhibited excellent efficiency in the photo-reduction of bicarbonate to formic acid, with CuInS2/ZnS showing the highest photon to formate conversion efficiency of 6.07 ± 0.07%. We attribute these exceptional results to their smaller bandgap leading to enhanced visible light absorption and the application of an appropriate hole scavenger that prolongs photo-generated charge carrier separation. To the best of our knowledge, the application of quantum dots in photocatalysis is still quite limited; this report describes the highest apparent quantum efficiency (AQE) to date.