Synergistic enhancement of bifunctional activity and stability of seawater electrolysis by in situ etching and concentration strategies

Abstract

An effective way to lessen the scarcity of freshwater resources is recognized as seawater electrolysis. Significant importance is attached to developing bifunctional catalysts appropriate for seawater electrolysis in industrial settings. In situ, etching and electrodeposition on nickel foam substrates were used in this study to create SNiFe@NF catalysts. Experiments demonstrated a positive link between catalytic activity and the KOH concentration in the electrolyte. The addition of sulfur not only increases catalytic activity but also increases resistance to Cl-. This is because sulfur has a low electronegativity, which helps to produce hydroxyl oxides by modulating the electronic structure between Ni and Fe. As predicted, at a current density of 100 mA cm−2, the SNiFe@NF catalyst demonstrated extraordinarily low overpotentials of 90 mV (HER) and 261 mV (OER). Moreover, after undergoing stability tests, the catalyst surface developed a SO42- layer that created a Cl- barrier, providing the basis for excellent stability. Interestingly, the electrolyzer used using SNiFe@NF catalysts also showed an outstanding 1.48 V at 100 mA cm−2 overall water splitting capacity. Furthermore, after 20 hours of continuous operation, no attenuation was seen in the catalysts' performance under high-temperature and high-alkalinity industrial settings. The results of this work provide a simple and efficient method for producing highly active bifunctional corrosion-resistant catalysts, which have significant ramifications for the development of the hydrogen economy.