Economical iron-based catalyst electrode for highly stable catalytic industrial-scale overall seawater splitting

Abstract

The development of economical and stable catalyst electrodes for industrial-scale seawater splitting is one of the current challenges in hydrogen production. The economical transition metals possess high electrical conductivity and offer the potential for designing electrodes with high intrinsic activity through appropriate modifications, thus holding promising applications in industrial contexts. Herein, a durable and economical self-supported bifunctional electrode (Fe@Ni) with high efficiency and large area is successfully constructed by one step in-situ deposition of iron on the porous structure of nickel foam (NF) via mild (298 K) electroplating method. Transition metals like iron and nickel offer high electrical conductivity and can be properly modified to achieve electrodes with high intrinsic activity. Due to the in-situ growth of cost-effective iron on the NF surface, the electrode surface morphology and electronic structure are reconstructed, which significantly improves the electrochemical activity surface area and electron transfer capability of the electrode. The hydrogen/oxygen evolution reaction (HER/OER) in simulated seawater (1 M KOH + 0.5 M NaCl) require only 129 mV and 323 mV overpotentials to achieve a current density of 100 mA cm−2. Overall seawater splitting (OWS) achieves 10 mA cm−2 at a low voltage of 1.49 V and with a faradaic efficiency of nearly 100%. More importantly, the bifunctional electrodes remain stable at industrial-level current density (1.0 A cm−2) for more than 50 days. More attractively, this work realizes the universal construction of large-area electrode for multiple metals (e.g., Fe, Cu, Al, etc.) with mild and simple process, which provides a new strategy for the current research of energy and materials.