Journal
NANO ENERGY
Volume 26, Issue -, Pages 405-416Publisher
ELSEVIER SCIENCE BV
DOI: 10.1016/j.nanoen.2016.05.051
Keywords
Cu dopant; Zn0.5Cd0.5S; Mechanism; Photocatalytic H-2 evolution; Water splitting; Visible light
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Funding
- National Project for EV Batteries [20121110]
- Guangdong Innovation Team Project [2013N080]
- U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences
- US Department of Energy-Basic Energy Sciences
- NSERC
- University of Washington
- Canadian Light Source and the Advanced Photon Source [AC02-06CH11357]
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Cu-doping into Zn1-xCdxS can greatly enhance the photocatalytic H-2 evolution from water splitting under visible-light irradiation. However, it is still controversial for how the Cu-dopant improves this performance. Here, we report that appropriate Cu-doped Zn0.5Cd0.5S nanocrystals reach 21.4 mmol/h/g of H-2 evolution rate without cocatalyst in the visible-light region, which is also 2.8 times as high as that of the undoped counterpart, and the corresponding apparent quantum efficiency is 18.8% at 428 nm. It is firstly confirmed that the Cu2+ changes into Cu+ after being doped by soft X-ray absorption spectroscopy (sXAS). We theoretically propose that the transformation of 2Cu(2+) to 2Cu(+) results in one adjacent S-2- vacancy (V-s) in host during the doping process, while the Cu+-dopant and V-s attract the photo excited holes and electrons, respectively. Accordingly, the photocatalytic activity is improved due to the enhanced separation of photoexcited carriers accompanied with the enhanced light absorption resulting from the Cu+-dopant and 2Cu(+)/V-s complex as possible active site for photocatalytic H-2 evolution. (C) 2016 Elsevier Ltd. All rights reserved.
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