Rationally engineered Co and N co-doped WS₂ as bifunctional catalysts for pH-universal hydrogen evolution and oxidative dehydrogenation reactions

In the field of electrolysis of water, the design and synthesis of catalysts over a wide pH range have attracted extensive attentions. In this paper, Co and N are co-introduced into the structural unit of tungsten disulfide (WS₂), and the hydrogen evolution reaction (HER) performances of different WS₂-based catalysts are theoretically predicted and systematically studied by density functional theory (DFT) calculations. With the guidance of DFT calculations, an evaporation-pyrolysis strategy is applied to prepare Co and N co-doped WS₂ (Co,N-WS₂) flower-like nanosheets, which exhibits excellent HER performance over a wide pH range. In addition, the DFT calculations show that the active sites in Co,N-WS₂ have a good ability of hydrogen adsorption after the introduction of Co and N, suggesting that such a co-doping system will be an ideal catalyst for oxidative dehydrogenation (ODH). The following experiment results indeed evidence that the Co,N-WS₂ catalyst displays a high activity in the ODH of 1,2,3,4-tetrahydroquinoline (4H-quinoline) and its derivatives. Therefore, this work provides a good example for the rational design and accurate preparation of functional catalysts, which enables it possible to develop other efficient catalysts with multiple functions.