Strong transboundary electron transfer of high-entropy quantum-dots driving rapid hydrogen evolution kinetics

Abstract

The sluggish Tafel kinetics and high noble metal usage of PtRu-based electrocatalysts in the hydrogen evolution reaction (HER) are the key challenges for practical proton exchange membrane water electrolysis (PEMWE). Here, highly dispersed sub-2 nm PtRuMoFeCoNi high-entropy alloy quantum dots (HEA-QDs) are synthesized through rapid microwave radiation. Advanced spectroscopy methods and theoretical calculations reveal that the strong transboundary electron transfer from Fe/Co/Ni/Mo to Pt/Ru sites weakens the strength of adsorbed hydrogen by enhancing the local electron density around Pt/Ru sites, thus effectively minimizing the Tafel step barrier. The synthesized HEA-QDs demonstrate superior HER activity with an overpotential of 11 mV@10 mA cm⁻², obviously outperforming that of Pt/C (18 mV@10 mA cm⁻²). Strikingly, the PEMWE device using HEA-QDs as a cathodic catalyst with an ultra-low loading of 100 μg_PtRu cm⁻² exhibits not only excellent performance (1.65 V@1.0 A cm⁻²), but also outstanding stability, even presenting a reduced cell voltage with a rate of −12.2 μV h⁻¹ over 1000 h of testing at 1.0 A cm⁻². Additionally, the HEA-QD cathode cell boasts an energy consumption of 3.98 kWh N m⁻³ H₂ (1.0 A cm⁻²) and a cost of US$0.88 per kg H₂, significantly exceeding the 2030 DOE target. This work offers new guidance for the precise construction of active centers with low kinetic barriers and their potential application in PEMWE devices with low noble metal usage.