PtO nanoclusters on ultra-thin 2D Mo₂C enhance hydrated cation interaction for superior alkaline hydrogen evolution reaction

Platinum oxide (PtO) is regarded as an effective catalyst beyond platinum metal for the hydrogen evolution reaction (HER). However, slow kinetics and structural instability limit its wide application as alkaline electrocatalyst. Herein, PtO nanoclusters decorated ultrathin two-dimensional (2D) Mo₂C with a Pt concentration of 0.98 wt% (Mo₂C-PtO) is designed and prepared to overcome these hurdles. The Mo₂C-PtO catalyst shows significant interfacial charge reconstruction and strong electrostatic interaction with hydrated ions and exhibits remarkable HER performance with an ultra-low overpotential of 5, 64 and 329 mV at 10, 100 and 1000 mA cm⁻² and a small Tafel slope of 25 mV dec⁻¹ in alkaline solution, as well as the long-term durability of hydrogen production at 500 mA cm⁻². In situ Raman scattering and theoretical calculation reveal the fast migration and dissociation of cationic hydration water at interface, which accelerates Volmer reaction. The key intermediates of OH* and H* transfer rapidly from the interface to Mo₂C and PtO, respectively, which increases the availability of interfacial sites and facilitates the fast Volmer-Tafel mechanism. This study highlights the potential of carbide-supported PtO nanoclusters as highly efficient catalysts for alkaline hydrogen production and offers insights into the interfacial water evolution mechanism. © 2025 Elsevier Inc.