Self-Supported Fe/NF Catalysts Modified with Strongly Hydrophobic Carbon Materials for Enhanced Water Electrolysis

Abstract

In this paper, a coal tar-based polymer (PCT) carbon material was electrochemically deposited onto the surface of nickel foam (NF) to obtain a strongly hydrophobic, self-supported electrode, PCT/NF. Subsequently, iron nanoparticles were further grown on PCT/NF by a second-step electrochemical deposition method to acquire a moderately hydrophobic Fe/PCT/NF electrode in 0.1 M FeCl3 electrolyte. SEM, XRD, Raman, and XPS confirmed that iron nanoparticles were grown on the graphene-like PCT with a water contact angle of 170°. The electrocatalytic water-splitting performances of the self-supported electrodes were systematically evaluated in 1 M KOH solution. The results demonstrated that the hydrophobic carbon material PCT coating not only enhanced electrical conductivity but also effectively suppressed the corrosion of Fe and Ni active species in the alkaline electrolyte. Consequently, the Fe/PCT/NF self-supported electrode exhibited a bifunctional electrocatalyst, achieving 10 mA cm–2 at overpotentials of 188 mV for the hydrogen evolution reaction (HER) and 285 mV for the oxygen evolution reaction (OER), respectively. For overall water splitting (OWS), a cell voltage of 1.56 V achieved a current density of 10 mA cm–2, and Fe/PCT/NF maintained long-term stability for 100 h with negligible current density fluctuation. This study provided a strategy for developing high-performance electrocatalysts for water splitting using rich coal tar as a carbon resource.