Sulfur-vacancy rich nonstoichiometric TiS2-x/NiS heterostructures for superior universal hydrogen evolution

Authors：Wu, Jing; Zhong, Wenda; Yang, Chenfan; Xu, Wenli; Zhao, Rong; Xiang, Hui; Zhang, Qin^*; Li, Xuanke^*; Yang, Nianjun^*

Source：Applied Catalysis B: Environmental , 2022, 310: 121332.

DOI：10.1016/j.apcatb.2022.121332

• Hydrogen evolution reaction
• Nonstoichiometric effect
• Sulfur vacancies
• d -band center
• Electronic structure

Water electrolysis has been recognized as one of the most promising approaches to produce green hydrogen and eventually target carbon neutrality. Various cost-effective and light transition metal sulfides have been developed as the electrocatalysts to promote hydrogen evolution reaction (HER), one half-reaction of water electrolysis. Unfortunately, full use of their intrinsic electrocatalytic traits and exposed active sites is still challenging. Here, a nonstoichiometric titanium sulfide/nickel sulfide (TiS2-x/NiS) hetero-catalyst is designed and constructed to induce a high-density of sulfur vacancies. As a HER electrocatalyst, it features the overpotentials of only 63 and 134 mV at a current density of 10 mA cm(-2) in 1.0 M KOH and 0.5 M H2SO4, respectively, which is equipped with glorious durability even at high current densities (e.g., 100 mA cm(-2) and 500 mA cm(-2)). Such outstanding performance partially stems from the sulfur vacancies induced by a nonstoichiometric effect, namely the intensified interfacial charge transfer nearby the TiS2-x/NiS heterointerface. The existence of sulfur vacancies partially regulates the d-electronic structure of Ti and Ni active sites, ultimately bringing in reduced energy barrier of water dissociation as well as optimized adsorption free energy for H* intermediates. The strategy of employing both a nonstoichiometric effect and interface engineering of a metal sulfide catalyst paves a new way to design high-performance and cost-effective HER electrocatalyst in universal media.

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