High Performance Nanostructured MoS₂ Electrodes with Spontaneous Ultra-Low Gold Loading for Hydrogen Evolution

The scarcity and cost of noble metals used in commercial electrolyzers limit the sustainability and scalability of water electrolysis for green hydrogen production. Herein, we report the ultralow loading of Au nanoparticles onto MoS₂ electrodes by the spontaneous process of galvanic deposition. AuNP@MoS₂ electrode synthesis was optimized, and electrodes containing the smallest Au nanoparticle diameter (2.9 nm) and the lowest Au loading (0.044 μg cm^–2) exhibited the best overall and intrinsic electrocatalytic performance. This enhancement is attributed to an increased Au–MoS₂ interaction with smaller nanoparticles, making the MoS₂ electrode more n-type. DC electrochemical characterization for the AuNP@MoS₂ electrodes showed an exchange current density of 7.28 μA cm–2 and an overpotential at 10 mA cm–2 of −323 mV. These values are 4.5 times higher and 100 mV lower than those of the unmodified MoS₂ electrode, respectively. Electrochemical AC experiments were used to evaluate the electrodes’ intrinsic catalytic activity, and it was shown that the AuNP@MoS₂ electrodes exhibited an enhanced activity by as much as 3.5 times compared with MoS2. Additionally, the turnover frequency as estimated by the reciprocal of the R_ctC_dl product, the latter calculated from the AC data, is estimated to be 58.8 s^–1 and is among one of the highest reported for composite MoS₂ materials.