Construction of a phosphorus-based integrated electrode for efficient and durable seawater splitting at a large current density

Abstract

Constructing economical and corrosion-resistant catalytic electrodes for efficient and high-current seawater splitting is a significant challenge. Herein, we employed a gentle, one-step immersion method to obtain an efficient and stable self-supporting integrated catalytic electrode via nickel foam (NF) etched in situ by sodium hypophosphite and trace ruthenium (Ru@P–NF). The successful growth of spherical Ru on the P–NF resulted in high intrinsic activity and rapid electron transfer capabilities. The Ru@P–NF electrode achieved a current density of 100 mA cm⁻² in the hydrogen evolution reaction (HER) with an overpotential of only 32 mV in an alkaline simulated seawater system (1 M KOH + 0.5 M NaCl). An overpotential of only 153 mV resulted in a current density of 10 mA cm⁻² in the oxygen evolution reaction (OER). Moreover, this electrode necessitated a mere 1.42 V at 20 mA cm⁻² to facilitate overall water splitting. Impressively, the operation of Ru@P–NF was stable at 100 mA cm⁻² for over 1500 hours without significant degradation, and thus demonstrated stable catalysis for an impressive 300 h at an industrial-level high current density in a weakly alkaline seawater and urine system. This work provides robust theoretical support for the construction of efficient industrial-scale catalytic electrodes for water electrolysis.