Proton exchange membrane (PEM) water electrolysis is a promising technology for producing green hydrogen from renewable energy. However, its large-scale deployment is hindered by the reliance on precious platinum-based catalysts. As a low-cost alternative, MoS2 has attracted considerable attention for the hydrogen evolution reaction (HER). Nevertheless, its catalytic performance is limited because active sites are primarily located at the S-edges, while the basal plane is largely inert. Therefore, simultaneously exposing and stabilizing MoS2 edge sites while enhancing the HER activity of both basal plane and edge sites remains a critical challenge.
Schematic illustration of Te substituting both Mo and S for high-efficiency HER (Image by Guomin Li)
In a study published in the Angewandte Chemie International Edition, a research team led by Prof. DENG Dehui, Prof. CUI Xiaoju, and Prof. YU Liang from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) developed a dual-site substitution strategy, in which single Te atoms simultaneously substitute for both Mo and S atoms in the MoS2 lattice. The resulting Te-MoS2 catalyst presents outstanding HER performance at large current densities in acidic electrolytes.
The researchers demonstrated that the Te-MoS2 catalyst requires an overpotential of only 364 mV to achieve an industrial-level current density of 1000 mA·cm-2, significantly lower than the 662 mV required for commercial 20 wt% Pt/C. Moreover, the catalyst maintains stable performance for 200 hours without decay.
Comprehensive analyses revealed that the simultaneous substitution of Mo and S with Te atoms not only activates neighboring S atoms but also promotes the formation of smaller, edge-rich MoS2 nanosheets, generating abundant active S sites on both the basal plane and edge regions while optimizing hydrogen adsorption.
"This work introduces the concept of single-element dual-site substitution, offering a valuable strategy for designing highly efficient MoS2-based catalysts for hydrogen evolution," said Prof. DENG.