Bimetallic Ru1−xVxO2 and trimetallic Ru1−x−yVxCryO2 alloy nanofibers for efficient, stable and pH-independent oxygen evolution reaction catalysis

Abstract

We present ruthenium-vanadium mixed alloy metal oxide (Ru1−xVxO2) nanofibers as well as chromium (Cr) doped Ru1−x−yVxCryO2 nanofibers using electrospinning and subsequent thermal annealing procedures as cost-effective, highly active and stable electrocatalyst for oxygen evolution reaction (OER). Both Ru1−xVxO2 and Ru1−x−yVxCryO2 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 Ru1−xVxO2 and Ru1−x−yVxCryO2 nanofibers showed excellent OER electrocatalytic activity, characterized by low overpotentials and small Tafel slopes, in both acidic and alkaline conditions. Ru1−xVxO2 (x = 0.52) nanofibers demonstrated an enhanced elemental substitution effect, leading to an enlarged active surface area that contributed to their exceptional OER activity. Ru1−x−yVxCryO2 nanofibers, achieved through optimal doping with Cr4+ ions, not only displayed significantly improved stability but also exhibited high OER activity. Interestingly, both Ru1−xVxO2 and Ru1−x−yVxCryO2 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. © 2023 Elsevier B.V.