4.7 Article

Electron-enriched regulation of sulfur-active site for accelerating atomic hydrogen desorption of S-rich MoWS2+x cocatalyst toward efficient photocatalytic H-2 evolution of TiO2

期刊

CHEMICAL ENGINEERING JOURNAL
卷 449, 期 -, 页码 -

出版社

ELSEVIER SCIENCE SA
DOI: 10.1016/j.cej.2022.137803

关键词

Photocatalysis; Cocatalysts; H-2 evolution; Active site regulation; Electron-enriched S atoms

资金

  1. National Natural Science Foundation of China [51872221, 22075220]
  2. 111 Project

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Metal chalcogenides (MSx) as H-2-evolution cocatalysts often have poor H desorption properties due to strong interfacial interactions with electronegative S sites, hindering the release of free H-2. A universal strategy involving electron-enriched regulation of sulfur-active sites by introducing W heteroatoms into MoS2+x has been developed to weaken S-Hads bonds and enhance hydrogen-evolution activity. This study demonstrates the importance of optimizing electron densities at active sites for the development of efficient catalytic materials.
Metal chalcogenides (MSx) as H-2-evolution cocatalysts generally suffer from unfavorable H desorption property because of the strong interfacial interaction between the adsorbed H and intensely electronegative S sites (S-H-ads, 363 KJ mol(-1)), which seriously hampers the H-ads from desorbing to generate free H-2. Herein, a universal strategy of electron-enriched regulation of sulfur-active site is developed to weaken the strong S-Hads bonds by introducing W heteroatoms into MoS2+x to form sulfur-rich MoWS2+x bimetal cocatalyst (expressed as MoWS2+x). In this case, the S-enriched MoWS2+x is skillfully produced and simultaneously anchored with the TiO2 by a facile photoinduced electron-reduction method, involving the aforehand formation of homogeneous W(MoS4)(x) and their subsequent in-situ photoinduced deposition procedure. Photoactivity experiments exhibit that the MoWS2+x/TiO2(2:1) sample obtains the highest H-2-evolution rate of 4620.8 mu mol h(-1) g(-1) (AQE = 22.2 %) with a great promotion of 3.6 folds compared to the MoS2+x/TiO2 sample. In situ/ex situ XPS characterizations and density functional theory (DFT) calculations reveal that the integration of W heteroatom into MoS2+x can regulate its electron density to form electron-enriched S(2+delta)- sites, thus availably weakening the S-H-ads bonds to optimize atomic H desorption and accordingly enhancing the hydrogen-evolution activity of TiO2. This study provides a unique idea to optimize the electron densities of activity sites, which is vital for the development of efficient catalytic materials.

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