V₂O₅ Nanowires with an Intrinsic Peroxidase‐Like Activity

Abstract

Abstract V 2 O 5 nanowires exhibit an intrinsic catalytic activity towards classical peroxidase substrates such as 2,2‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid) (ABTS) and 3,3,5,5,‐tetramethylbenzdine (TMB) in the presence of H 2 O 2 . These V 2 O 5 nanowires show an optimum reactivity at a pH of 4.0 and the catalytic activity is dependent on the concentration. The Michaelis‐Menten kinetics of the ABTS oxidation over these nanowires reveals a behavior similar to that of their natural vanadium‐dependent haloperoxidase (V‐HPO) counterparts. The V 2 O 5 nanowires mediate the oxidation of ABTS in the presence of H 2 O 2 with a turnover frequency ( k cat ) of 2.5 × 10 3 s −1 . The K M values of the V 2 O 5 nanowires for ABTS oxidation (0.4 μ M ) and for H 2 O 2 (2.9 μ M ) at a pH of 4.0 are significantly smaller than those reported for horseradish peroxidases (HRP) and V‐HPO indicating a higher affinity of the substrates for the V 2 O 5 nanowire surface. Based on the kinetic parameters and similarity with vanadium‐based complexes a mechanism is proposed where an intermediate metastable peroxo complex is formed as the first catalytic step. The nanostructured vanadium‐based material can be re‐used up to 10 times and retains its catalytic activity in a wide range of organic solvents (up to 90%) making it a promising mimic of peroxidase catalysts.