Tailoring the electronic structure of an Ni2P aerogel via ruthenium doping for energy-efficient hydrogen generation in anion-exchange membrane-based seawater electrolysis

Abstract

Alkaline seawater electrolysis is confronted with considerable challenges, including the underperformance of bifunctional catalysts in terms of catalytic activity and susceptibility to chlorine-induced corrosion. In this study, an Ni₂P aerogel with ruthenium heteroatoms (Ru-Ni₂P AG/nickel foam (NF)) was synthesized through a novel electrochemically assisted strategy including electrodeposition and voltage-induced cation enrichment effects. The incorporation of Ru species provided resistance to chloride ion corrosion and effectively modulated the local electronic structure of Ni₂P, increasing the intrinsic activity of Ni₂P AG/NF. Concurrently, the highly porous aerogel provided exposed active centers and interconnected mass transport channels. Consequently, Ru-Ni₂P aerogel/NF demonstrated remarkable performance and required overpotentials of merely 33 mV and 148 mV to achieve 10 mA cm⁻² under artificial seawater conditions (1.0 M KOH + 0.5 M NaCl) for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. Furthermore, a stable, high-efficiency and energy-saving seawater electrolysis operation was achieved through the utilisation of Ru-Ni₂P aerogel/NF as the anode and cathode (1.53 V at 100 mA cm⁻²), coupled with satisfactory stability for 80 h without significant degradation. The intrinsic active sites of Ru-Ni₂P AG/NF for the HER and OER were studied via density functional theory (DFT) calculations, with each site performing its own function. From morphological modulation and electrical engineering perspectives, the innovative design of aerogel electrocatalysts constructed directly on the collector presents a novel concept for advanced catalytic applications in seawater media.