Iron-hydroxide controlled by cobalt and aluminium as an advanced electrocatalysts for overall water splitting and its temperature dependence

Abstract

Multimetal hydroxide catalysts have the potential to combine their advantages to facilitate the synergistic effects for enhanced catalytic activity in alkaline medium. In this work we assessed the performance of the electrodeposited Cox-Fey-Alz hydroxide electrode as an electrocatalyst in an alkaline electrolyzer, showcasing its superior functionality compared to other control systems. The catalysts demonstrate exceptional electrochemical properties, achieving low overpotentials of η = 264 mV for OER and η = 197 mV for HER at a current density of 100 mA cm−2. Moreover, they maintain excellent durability even after 50 hours of continuous operation and exhibit a low Tafel slope of 41.4 mV dec−1. Temperature-dependent studies in electrocatalysis become particularly relevant when we consider the practical applications of these remarkable catalysts. A water electrolyzer constructed using the Cox-Fey-Alz hydroxide at the anode and cathode displays an extremely low cell voltage of 1.56 V at 25°C and 1.47 V at 55 °C, respectively, at a current density of 10 mA cm−2 for 50 h. The variation in temperature from 25 °C to 55 °C has a substantial impact on the overall performance, emphasizing the need for temperature-dependent studies. Understanding the catalyst's behaviour under different temperature regimes is crucial for optimizing its efficiency and durability in real-world applications. This insight can lead to the development of more energy-efficient and robust electrochemical systems for a sustainable future. © 2024 Elsevier B.V.