The development of high-performance and non-platinum electrocatalysts capable of operating at industrial-scale current densities is crucial for cost-effective green hydrogen production. While rhenium (Re) exhibits promising attributes, its implementation is hindered by the difficulty in synthesizing metallic Re and the suboptimal activity of its bulk forms. Herein, we demonstrate a facile electrochemical strategy to immobilize Re single atoms onto a Co, Mo-doped NiSe₂/NiCoMo alloy heterostructure (Re_SA-NiCoMo-Se) in a deep eutectic solvent. The optimized electrocatalyst delivers exceptional hydrogen evolution reaction (HER) performance in alkaline media, requiring ultralow overpotentials of only 23 and 292 mV at current densities of 10 and 1000 mA·cm⁻², respectively. When configured as a cathode in a flowing alkaline water electrolyzer, it enables competitive water splitting performance and robust operational stability for over 500 h. Structural characterization and theoretical calculations reveal that the atomically dispersed Re sites act as the active centers to facilitate the water dissociation and optimize hydrogen adsorption energy, simultaneously triggering a profound electron redistribution within the heterostructure support that leads to a collective enhancement of the reaction kinetics. This study showcases the feasibility of synthesizing Re single-atom materials via the electrochemical approach and highlights their potential as high-performance and stable electrocatalysts suitable for industrial applications.

Platinum (Pt)-based materials have garnered significant attention due to their exceptional electrocatalytic performance and potential for advancing water splitting technology. However, reducing Pt usage simultaneously maintaining its high catalytic performance remains a critical challenge. Here, ultralow content (0.25 wt.‰) of Pt single atoms (SAs) was successfully anchored onto Ti_3−xC₂T_y MXene nanosheets, followed by the preparation of self-supported, densified MXene film electrocatalysts through a sequential bridging process involving hydrogen and covalent bonding (denoted as 0.25-HCM@Pt_SA). The resulting 0.25-HCM@Pt_SA film catalyst exhibits excellent hydrogen evolution reaction (HER) performance, showcasing a small overpotential of 48 mV at 10 mA·cm⁻², an ultrahigh mass activity of 28.93 A·mg_Pt⁻¹, and a large turnover frequency of 23.45 s⁻¹ at an overpotential of 100 mV. Furthermore, density functional theory calculations reveal that the anchoring Pt SAs on the densified MXene film reduce the binding energy and hybridization strength between H atoms and the support, contributing to rapid hydrogen adsorption–desorption kinetics and high HER activity. This work provides a promising and scalable strategy for designing two-dimensional (2D) materials-based noble metal electrocatalysts with ultralow metal loading and high catalytic activity.