Time-resolved spectroscopic studies of photocatalytic water splitting on semiconductor nanocrystals

Semiconductor nanocrystals hold promise for efficient solar to hydrogen conversion, but the progress is hindered by the gaps in the understanding of the charge transfer mechanism in the nanostructures.[1] Here, we employ ultrafast transient absorption and time-resolved photoluminescence spectroscopies to study the charge transfer dynamics in photocatalytic water splitting on cadmium chalcogenide nanocrystals. We demonstrate that through determining the limiting steps and through design of the nanostructures for the charge separation and recombination rates, nearly 100% quantum efficiency of hydrogen production can be achieved.[2-5] In addition, we show that combining the semiconductor nanocrystals with molecular catalyst enables complete water splitting into hydrogen and oxygen, without the use of any sacrificial agents.[6] Finally, we discuss the challenges facing the field of photocatalytic water splitting.
1. J.K. Stolarczyk et al., ACS Catalysis 2018, 8, 3602–3635
2. T. Simon et al., Nat. Mater. 2014, 13, 1013-1018
3. T. Simon et al., ACS Energy Lett. 2016, 1, 1137-1142
4. A. Manzi et al. J. Am. Chem. Soc. 2015, 137, 14007-14010
5. S. Bhattacharyya et al. Nat. Commun. 2017, 8, 1401.
6. C. Wolff et al., submitted.