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Issue 14, 2018
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Surface stoichiometry manipulation enhances solar hydrogen evolution of CdSe quantum dots

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Abstract

Surface stoichiometry is a sensitive parameter affecting the decay dynamics of photogenerated hole–electron pairs of QDs. However, the effect of this manipulation on artificial photocatalytic H2 evolution is unclear. Here, we report that surface stoichiometry manipulation is a facile and feasible approach for enhancing H2 photogeneration of QDs. In the absence of an external cocatalyst, a decrease in the surface Se ratio of CdSe QDs from ∼16.7% to ∼4.9% gives a more than 10-fold increase in solar H2 evolution. Taking Ni(II) as an external cocatalyst, CdSe QDs with a surface Se ratio of ∼4.9% can produce ∼1600 ± 151 μmol H2 gas during 27 h of visible-light irradiation, giving a total turnover number of (1.24 ± 0.12) × 105 on CdSe QDs and an apparent quantum yield of 10.1%, which is about 8 times that of CdSe QDs with a surface Se ratio of ∼16.7% under the same conditions. Mechanistic insights obtained by a combination of steady-state and time-resolved spectroscopic techniques indicate that surface stoichiometry exerts a significant influence on the exciton kinetics of CdSe QDs: a higher ratio of surface Se would increase the possibility of exciton recombination through hole trapping, thus depressing the performance of solar H2 evolution.

Graphical abstract: Surface stoichiometry manipulation enhances solar hydrogen evolution of CdSe quantum dots

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Publication details

The article was received on 12 Jan 2018, accepted on 06 Mar 2018 and first published on 07 Mar 2018


Article type: Paper
DOI: 10.1039/C8TA00385H
Citation: J. Mater. Chem. A, 2018,6, 6015-6021
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    Surface stoichiometry manipulation enhances solar hydrogen evolution of CdSe quantum dots

    M. Huang, X. Li, Y. Gao, J. Li, H. Wu, L. Zhang, C. Tung and L. Wu, J. Mater. Chem. A, 2018, 6, 6015
    DOI: 10.1039/C8TA00385H

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