Ultralow iridium content and oxygen vacancy-rich Ir–Co3O4 electrocatalyst to boost acidic oxygen evolution

It is essential to develop cost-effective and high durable electrocatalysts for efficient acidic oxygen evolution reaction (OER) for the large-scale industrial hydrogen production of proton exchange membrane water electrolyzers (PEMWEs). Herein, self-supported V_O-Ir-Co₃O₄@CFP with three-dimensional petal-like microstructure and abundant oxygen vacancies was prepared on carbon fiber paper (CFP) matrix by a simple hydrothermal reaction-spontaneous galvanic displacement-calcination-solution reduction approach. The resultant V_O-Ir-Co₃O₄@CFP manifests dual advantages in both cost and superior electrocatalytic performance for OER, which has IrO₂ content of as low as 0.202 mg cm⁻² and exhibits remarkably superior catalytic activity towards OER with a low overpotential of only 169 mV at 10 mA cm⁻², a Tafel slope of 39.8 mV dec⁻¹, and excellent long-term durability at a large current density of 100 mA cm⁻² for 50 h consecutive water oxidation. Moreover, V_O-Ir-Co₃O₄@CFP exhibits the mass activity of 461.77 mAcm⁻² mg_Ir⁻¹, which is 34 times higher than that of benchmark IrO₂. This work provides a strategy of fabricating catalysts with exceptional OER performance through galvanic displacement reaction and creating oxygen vacancies via chemical reduction.