Recovery of Active and Efficient Photocatalytic H2 Production for CdSe Quantum Dots

Abstract

Recently, colloidal semiconductor quantum dots (QDs) have shown great promise as photocatalysts for the production of chemical fuels by sunlight. Here, the efficiency of photocatalytic hydrogen (H2) production for integrated systems of large diameter (4.4 nm) CdSe QDs as light harvesting nanoparticles with varying concentrations of nickel–dihydrolipoic acid (Ni–DHLA) small molecule catalysts is measured. While exhibiting excellent robustness and longevity, the efficiency of H2 production for equimolar catalyst and QDs is relatively poor. However, the efficiency is found to increase substantially with increasing Ni–DHLA/QD molar ratios. Surprisingly, this high activity is only observed with the use of 3-mercaptopropionic acid (MPA) ligands, while CdSe QDs capped with dihydrolipoic acid (DHLA) exhibit poor performance in comparison, indicating that the QD capping ligand has a substantial impact on the catalytic performance. Ultrafast transient absorption spectroscopic measurements of the electron transfer (...