Ni–Fe-based alloy as oxygen evolving anode for sustainable aluminum production

Abstract

Achieving global net-zero carbon targets by 2050 requires the decarbonization of metal production. Molten salt electrolysis, combined with the rapidly expanding renewable energy sector, provides a transformative and sustainable alternative to conventional metallurgical processes and reduces greenhouse gas emissions. Today, aluminum is produced by electrolysis in molten fluoride melts, using consumable carbon anodes for their feasibility, low cost, good conductivity, and efficient reaction kinetics. However, achieving carbon-free aluminum production requires the development of a cost-effective, non-consumable, and efficient oxygen evolving anode (OEA)—a critical challenge that remains unsolved. Here, we demonstrate an earth-abundant and easily processable Ni–Fe-based anode, capable of forming a protective NiFe2O4 oxide, both ex-situ and in-situ, that enhances stability and catalytic activity for OEA. The principal approach to evaluating OEA alloy suitability combines analyzing oxide thermodynamics, investigating oxidation kinetics, and performing extended electrolysis in fluoride melts to elucidate the mechanism of protective oxide formation. By optimizing the Ni/Fe ratio in alloy, we demonstrate reduced alloy corrosion, high purity aluminum production, and efficient oxygen evolution. This method lays the framework for a durable and active Ni–Fe-based OEA, thereby advancing carbon-free sustainable aluminum production.