Boosting alkaline hydrogen evolution reaction kinetics by a local electric field created by polarization of CeO₂(100)

In this study, a simple and versatile strategy is demonstrated to create acid-like local environments (ALLE) to boost alkaline hydrogen evolution reaction (HER) kinetics of Pt/C, Pt/CoS₂, and other electrocatalysts by introducing a local electric field (LEF) stemming from the polar-faceted cubic CeO₂ (C–CeO₂). The surface polarity of the C–CeO₂ facets is confirmed by trimethylphosphine oxide-³¹P nuclear magnetic resonance. Operando Raman scattering provides evidence that H₃O⁺ intermediates produce the ALLE. This ALLE shows great enhancement in alkaline HER with activities of the C–CeO₂ modified Pt/C and Pt/CoS₂ promoted by 2.5 and 5.5 times compared to the counterparts, respectively. The LEF changes the mechanism from slow Volmer–Heyrovsky to fast Volmer–Tafel process. As a result, Pt/CoS₂ + C–CeO₂ shows a small Tafel slop of 23.8 mV dec⁻¹ and low overpotentials of 20 and 59 mV at current densities of 10 and 100 mA cm⁻², respectively. Importantly, the LEF produces similar effects in other electrocatalysts. © 2023 Hydrogen Energy Publications LLC.