Bimetallic Ru_1−xV_xO₂ and trimetallic Ru_1−x−yV_xCr_yO₂ alloy nanofibers for efficient, stable and pH-independent oxygen evolution reaction catalysis

We present ruthenium-vanadium mixed alloy metal oxide (Ru_1−xV_xO₂) nanofibers as well as chromium (Cr) doped Ru_1−x−yV_xCr_yO₂ nanofibers using electrospinning and subsequent thermal annealing procedures as cost-effective, highly active and stable electrocatalyst for oxygen evolution reaction (OER). Both Ru_1−xV_xO₂ and Ru_1−x−yV_xCr_yO₂ nanofibers exhibited tetragonal crystalline structure, confirming that Ru, V, and Cr ions randomly occupied the tetragonal lattice sites due to the similar ionic sizes. Both Ru_1−xV_xO₂ and Ru_1−x−yV_xCr_yO₂ nanofibers showed excellent OER electrocatalytic activity, characterized by low overpotentials and small Tafel slopes, in both acidic and alkaline conditions. Ru_1−xV_xO₂ (x = 0.52) nanofibers demonstrated an enhanced elemental substitution effect, leading to an enlarged active surface area that contributed to their exceptional OER activity. Ru_1−x−yV_xCr_yO₂ nanofibers, achieved through optimal doping with Cr⁴⁺ ions, not only displayed significantly improved stability but also exhibited high OER activity. Interestingly, both Ru_1−xV_xO₂ and Ru_1−x−yV_xCr_yO₂ nanofibers consistently catalyzed alkaline OER, even under conditions of reactant depletion. These nanofibers, containing noble Ru with less than half of the total metal content, are proposed as efficient and cost-effective OER catalysts for use in both acidic and alkaline media.