Ultrafast Joule heating-induced formation of amorphous CoFeNi phosphate for efficient and stable oxygen evolution reaction

Abstract

Developing efficient and durable non-precious metal-based catalysts for the oxygen evolution reaction (OER) in water electrolysis is crucial for large-scale and affordable hydrogen production. Many transition metal-based OER catalysts have been explored, but controlling their transformation into active oxyhydroxides during reconstruction, with fast reaction kinetics and low energy barriers, remains challenging. This article reports an ultrafast Joule heating strategy to synthesize efficient and stable amorphous transition metal phosphate electrocatalysts from metal chlorides and phytic acid precursors within 100 milliseconds at around 420 °C. The resulting amorphous CoFeNi phosphate coated on a superhydrophilic activated carbon cloth (CoFeNiPi@ACC) delivered a low overpotential of 235 mV at 10 mA cm⁻², a small Tafel slope of 32.2 mV dec⁻¹, and high stability for OER in 1.0 M KOH solution over 100 hours. The transient Joule heating process facilitates the rapid formation of an amorphous metal phosphate structure with abundant active sites, higher oxidation states for metal cations, self-reconstruction into active metal oxyhydroxides, and enhanced charge carrier diffusion rates, resulting in outstanding OER performance. This approach could be extended to other advanced material combinations for sustainable and efficient renewable energy production and storage.