Layered vanadium oxide nanofibers as impressive electrocatalyst for hydrogen evolution reaction in acidic medium.

Development of abundant and cost-effective electrocatalysts for hydrogen evolution reaction (HER) has gained momentum in recent years. In spite of being one of the largest class of materials, very few metal oxides have shown the propensity for HER in acidic medium. Herein, we report V 10 O 24.nH 2 O nanofibers as an excellent electrocatalyst material for HER for the first time. We show that V 10 O 24.nH 2 O nanostructures with a mixed V5+/V4+ oxidation state and a jute-fiber like morphology having a layered disposition and large interlayer spacing of 1.3 nm characterized by interlayer water molecules, can act as an excellent HER electrocatalyst in acidic medium. It required a low overpotential of 118 mV reaching to −10 mA cm−2 current density and at 600 mV overpotential reached a current density of −405 mA cm−2. It showed excellent durability retaining ca. 90% of its initial activity even after cycling for more than 11 h. Mechanism of the HER electrocatalysis was investigated by Tafel analysis that revealed typical Volmer-Heyrovsky mechanism for the HER with an excellent exchange current density of 1.62 mA cm−2. The vanadium oxide catalyst was also explored as oxygen reduction reaction electrocatalyst for application in alkaline fuel-cells. • Layered V 10 O 24.nH 2 O nanofibers with large interlamellar spacings of ∼ 1.3 nm was synthesized via hydrothermal method. • HER activity was achieved in acidic medium, one of the rare instances where metal oxides have been reported for the same. • Requires low overpotentials of -126 and 600 mV to achieve current densities of -10 mAcm-2 and -425 mAcm-2, respectively. • Nanofibers were also active for oxygen reduction reaction in alkaline medium with onset potential of ∼ 0.67 V vs RHE. [ABSTRACT FROM AUTHOR]