Regulation of the surface micro-structure and crystal phase of Pd2B mesoporous nanoparticles for enhanced hydrogen evolution electrocatalysis

Abstract

The hydrogen evolution reaction (HER) is the crucial cathodic half-reaction in electrocatalytic water splitting systems. The development of highly efficient catalysts that can trigger proton reduction with minimal overpotential and have fast kinetics is pivotal for sustainable hydrogen production by means of the HER. Crystal phase engineering and surface functionalization as feasible strategies have attracted growing interest in modulating the HER reactivity of metal-based catalysts. Herein, polyethylenimine-modified Pd₂B mesoporous nanoparticles (Pd₂B@PEI mNPs) with a stable hexagonal close-packed (hcp) phase were rationally designed and successfully prepared by a two-step strategy using Pd mesoporous nanoparticles as the starting material. With the dominant HER-active hcp Pd boride phase and modified surface micro-structure (e.g., increased interfacial proton concentration), the electrocatalytic activity of the as-prepared Pd₂B@PEI mNPs for hydrogen evolution in acid electrolyte exceeds those of unmodified Pd₂B mNPs and even commercial Pt/C. This study provides new insights for catalyst design through collaborative interface engineering and component modulation.