Interface Engineering of AuCu Bimetallic Nanoparticles/1T-MoS ₂ Electrocatalyst for Enhanced Hydrogen Evolution Reaction Activity in Natural Seawater and Alkaline Freshwater

Developing robust, high-performance electrochemical catalysts for hydrogen production from natural seawater or alkaline freshwater presents a significant challenge. Herein, we report an electrocatalyst system of AuCu bimetallic nanoparticles (NPs) supported on 1T-MoS 2 (AuCu/1T-MoS 2 ) synthesized via hydrothermal/solvothermal methods followed by controlled electrochemical deposition. Experimental electrochemical measurements combined with density functional theory (DFT) calculations reveal that the AuCu/1T-MoS 2 catalyst exhibits superior hydrogen evolution reaction (HER) activity in alkaline freshwater compared with natural seawater. DFT indicates that adsorption of Na + or Cl – on the active Au sites makes the Gibbs free energy of hydrogen adsorption (Δ G H ) more negative, thereby disfavoring H 2 desorption and reducing activity in seawater. Experimentally and theoretically, the introduction of AuCu NPs increases the density of accessible active sites by activating the otherwise inert basal planes of 1T-MoS 2 . The Cu component facilitates water dissociation and lowers Δ G H, while Au improves the electrical conductivity. The orbital hybridization between the d states of AuCu and those of Mo in 1T-MoS 2 results in a higher density of states at the Fermi level, thereby improving conductivity and reducing Δ G H . Charge redistribution at the AuCu/1T-MoS 2 interface produces a synergistic enhancement of HER kinetics. Our findings offer design principles for bimetallic/2D hybrid electrocatalysts tailored for seawater and alkaline electrolysis.