Ligand removal from CdS quantum dots for enhanced photocatalytic H2 generation in pH neutral water

Abstract

Ligand-free CdS quantum dots were produced by a reactive ligand stripping procedure and employed for photocatalytic H₂ evolution in pH neutral solution. The rate of H₂ generation of the ‘bare’ quantum dots was 175 times higher than that of the equivalent mercaptopropionic acid-capped quantum dots in the presence of a cobalt co-catalyst and Na₂SO₃ as a sacrificial electron donor. Under optimised conditions, a turnover number of 58 000 mol H₂ per mol Co and 29 000 mol H₂ per mol CdS quantum dots was achieved after 88 h of UV-free solar light irradiation (λ > 420 nm, 1 Sun intensity). Ligand removal is therefore a potent method to substantially enhance the photocatalytic performance of quantum dot systems.