Green hydrogen production via anion exchange membrane water electrolysis by precious metal-free high-entropy oxides

The development of efficient and affordable technologies for green hydrogen production can significantly help the transition to sustainable energy systems. Among them, anion-exchange membrane water electrolysis (AEMWE) can offer an appealing balance between performance and cost. This requires simple methods for the large-scale synthesis of efficient and low-cost electrocatalysts. In this paper, precious metal-free high-entropy oxides synthesized by the sol-gel method and calcination at different temperatures (400800 °C) are utilized to fabricate the anode of a zero-gap AEMWE full cell, while for the fabrication of the cathode they are first reduced in a H2/Ar atmosphere. The effect of calcination temperature on the cell electrochemical performance, as resulting from the physicochemical properties of the obtained electrode materials, is studied. The electrode pair obtained from the oxide calcined at 600°C allows achieving a current density of 1.33 A cm2 at a potential of 1.93 V at 50°C in 1M KOH electrolyte. Besides, it is capable of operating at current densities reaching even 1.0 A cm2 for 1100 h at a cell potential never exceeding 2.1 V. Overall, the study provides insights into the temperature-driven evolution of multicomponent oxide catalyst properties and its impact on AEMWE performance, contributing to the rational design of efficient and scalable materials for practical applications in sustainable hydrogen generation.