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An on-demand solar hydrogen-evolution system for unassisted high-efficiency pure-water splitting

Solar water splitting of pure water offers an attractive means for sustainable and carbon-free H 2 production. However, current photocatalytic H 2 production systems still suffer from two basic issues: the kinetic bottleneck for O 2 release and the easy toxicity of the photocatalysts. Here, we devel...

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Bibliographic Details
Published in:Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2019, Vol.7 (29), p.17315-17323
Main Authors: Che, Wei, Su, Hui, Zhao, Xu, Li, Yuanli, Zhang, Hui, Zhou, Wanlin, Liu, Meihuan, Cheng, Weiren, Hu, Fengchun, Liu, Qinghua
Format: Article
Language:English
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Summary:Solar water splitting of pure water offers an attractive means for sustainable and carbon-free H 2 production. However, current photocatalytic H 2 production systems still suffer from two basic issues: the kinetic bottleneck for O 2 release and the easy toxicity of the photocatalysts. Here, we developed a consolidated photocatalyst, namely g-C 3 N 3.5 (O 0.5 H 0.5 ), that can boost sustainable and superior H 2 evolution without using any sacrificial reagent. By conceptual design analysis as the guideline for three synthetic steps, the surface hydroxylation structure of g-C 3 N 3.5 (O 0.5 H 0.5 ) concurrently increases the toxicity resistance and maximizes the charge separation for H 2 evolution. The obtained surface-hydroxylated g-C 3 N 3.5 (O 0.5 H 0.5 ) photocatalyst exhibited unassisted high-efficiency pure-water-splitting activity, with a benchmark H 2 -evolution rate up to 947.7 μmol h −1 g −1 under visible-light irradiation. Notably, the quantum efficiency of the g-C 3 N 3.5 (O 0.5 H 0.5 ) suspension reached ∼10.6 and ∼2.5% at 420 and 520 nm, respectively, 10-20 times that of pristine g-C 3 N 4 . For the first time, we observed a key phenomenon that H 2 O molecules can rapidly capture the photoexcited holes to produce H 2 O 2 , which can greatly promote the efficient charge separation for high H 2 evolution. A surface hydroxylation structure of g-C 3 N 3.5 (O 0.5 H 0.5 ) photocatalyst was designed to concurrently increase the toxicity resistance and maximize the charge separation for H 2 evolution.
ISSN:2050-7488
2050-7496
DOI:10.1039/c9ta05142b