Bridging-induced densified MXene films with ultralow single-atom Pt loading for highly efficient hydrogen evolution

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.