Ligand removal from CdS quantum dots for enhanced photocatalytic H-2 generation in pH neutral water

Ligand-free CdS quantum dots were produced by a reactive ligand stripping procedure and employed for photocatalytic H-2 evolution in pH neutral solution. The rate of H-2 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 H-2 per mol Co and 29 000 mol H-2 per mol CdS quantum dots was achieved after 88 h of UV-free solar light irradiation (lambda > 420 nm, 1 Sun intensity). Ligand removal is therefore a potent method to substantially enhance the photocatalytic performance of quantum dot systems.