Electrochemical synthesis of wormcast-like Pd-based polycrystalline high entropy aggregates for methanol water co-electrocatalysis†

Abstract

High entropy compound (HEC) nanostructures have attracted considerable attention for various electrocatalysis reactions due to their unique physicochemical features provided by the adjustable multi-elemental synergy. However, there is a lack of focus on grain boundary engineering in HEC nanomaterials for enhanced electrocatalysis. Herein, wormcast-like PdFeCoNiCu polycrystalline high-entropy nanomaterials (PdFeCoNiCu-pHENs) are synthesized by a facile two-stage potential electrodeposition method. The as-synthesized PdFeCoNiCu-pHENs wormcast-like porous nanostructure enriches grain boundary defects, which exhibit superior electroactivity toward both the hydrogen evolution reaction (HER) and methanol oxidation reaction (MOR), as well as excellent MOR-coupled hydrogen production in alkaline media. Benefiting from the electron synergistic effect of multiple elements and the full distribution of massive grain boundary defects in novel wormcast-like polycrystalline aggregation, PdFeCoNiCu-pHENs exhibited great MOR (a specific activity of 52.5 mA cm⁻²) and HER (an overpotential of 38.4 mV versus RHE at 10 mA cm⁻²) electroactivities and efficient MOR-assisted hydrogen generation (the required cell voltage of 1.11 V at 100 mA cm⁻²) ability. This study offers a new strategy to develop advantageous high-entropy electrocatalysts for efficient energy-saving hydrogen production.