One-pot synthesis of K-doped g-C3N4 nanosheets with enhanced photocatalytic hydrogen production under visible-light irradiation

[Display omitted] •Synthesis of K-doped g-C3N4 by one-pot calcination.•K-doped g-C3N4 reduced the electron-hole recombination rate.•K-doped increased the polymerization degree and π-conjugated systems of g-C3N4.•K-doped g-C3N4 increased the photocatalytic performance significantly. Graphite carbon n...

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Bibliographic Details
Published in:Applied surface science 2018-05, Vol.440, p.258-265
Main Authors: Wang, Yanyun, Zhao, Shuo, Zhang, Yiwei, Fang, Jiasheng, Zhou, Yuming, Yuan, Shenhao, Zhang, Chao, Chen, Wenxia
Format: Article
Language:English
Subjects:
g-C3N4
K-doped
Photocatalytic hydrogen evolution
π-conjugated system
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Summary:[Display omitted] •Synthesis of K-doped g-C3N4 by one-pot calcination.•K-doped g-C3N4 reduced the electron-hole recombination rate.•K-doped increased the polymerization degree and π-conjugated systems of g-C3N4.•K-doped g-C3N4 increased the photocatalytic performance significantly. Graphite carbon nitride (g-C3N4), as a promising low cost, visible light driven conjugated polymer semiconductor photocatalyst, has attracted wide attentions from researchers. However, low light absorption efficiency and inadequate charge separation limit the potential applications of g-C3N4. This paper exhibits K-doped g-C3N4 prepared by a facile thermal polymerization with KBr as the K source. The experiments of photocatalytic hydrogen evolution demonstrate that KBr content strongly affects the activity of the catalyst. XRD, FT-IR, XPS, SEM, TEM, UV–vis diffuse reflectance spectra, photoluminescence (PL) characterization methods are used to study the effects of potassium on the catalyst performance. The results find that K-modified g-C3N4 has a narrower band gap and enhanced light harvesting properties. Moreover, the photocatalytic hydrogen evolution rate (HER) of the optimized K-doped g-C3N4 nanosheets (10 wt % KBr) reaches 1337.2 μmol g−1h−1, which is about 5.6 times in comparison with that of pure g-C3N4 (239.8 μmol g−1h−1). The doping of the potassium may increase the π-conjugated systems and accelerate the electron transport rate, then improve the photocatalytic properties. Based on the results of the analysis, a possible mechanism is proposed.
ISSN:0169-4332
1873-5584
DOI:10.1016/j.apsusc.2018.01.091