Abstract: Electrocatalyst designs based on oxophilic foreign atoms are considered a promising approach for devel-oping efficient pH-universal hydrogen evolution reaction (HER) electrocatalysts by overcoming the slug-gish alkaline HER kinetics. Here, we design ternary transition metals-based nickel telluride (MoWNiTe) catalysts consisting of high valence non-3d Mo and W metals and oxophilic Te as a first demonstration of non-precious heterogeneous electrocatalysts following the bifunctional mechanism. The MoWNiTe showed excellent HER catalytic performance with overpotentials of 72, 125, and 182 mV to reach the cur-rent densities of 10, 100, and 1000 mA cm^-2, respectively, and the corresponding Tafel slope of 47, 52, and 58 mV dec^-1 in alkaline media, which is much superior to commercial Pt/C. Additionally, the HER performance of MoWNiTe is well maintained up to 3000 h at the current density of 100 mA cm^-2. It is further demonstrated that the MoWNiTe exhibits remarkable HER activities with an overpotential of 45 mV (31 mV) and Tafel slope of 60 mV dec^-1 (34 mV dec^-1) at 10 mA cm^-2 in neutral (acid) media. The superior HER performance of MoWNiTe is attributed to the electronic structure modulation, inducing highly active low valence states by the incorporation of high valence non-3d transition metals. It is also attributed to the oxophilic effect of Te, accelerating water dissociation kinetics through a bifunctional cat-alytic mechanism in alkaline media. Density functional theory calculations further reveal that such syn-ergistic effects lead to reduced free energy for an efficient water dissociation process, resulting in remarkable HER catalytic performances within universal pH environments.

Key words: Telluride catalyst, Oxophilic effect, High valence non-3d metal, Bifunctional mechanism, pH-universal hydrogen evolution reaction