Phosphomolybdate@Carbon‐Based Nanocomposites as Electrocatalysts for Oxygen Reduction Reaction

Abstract Functional materials as electrocatalysts for the oxygen reduction reaction (ORR) are crucial for several renewable energy applications. Herein, we report the application of several nanocomposites, prepared by the incorporation of a vanadium‐substituted phosphomolybdate [PMo 11 VO 40 ] 4− (PMo 11 V) into some carbon‐based materials (carbon black (CBV), single‐walled carbon nanotubes (SWCNT) and graphene (GF)), as ORR electrocatalysts. All nanocomposites, denominated as PMo 11 V@CBV, PMo 11 V@SWCNT and PMo 11 V@GF, show electrocatalytic activity for the ORR in acidic medium (pH 2.5 H 2 SO 4 /Li 2 SO 4 buffer solution), with a strong dependency between the electrocatalytic ORR performance and the carbon‐based material employed. Among the materials studied, the PMo 11 V@GF nanocomposite exhibits the most promising performance, having the less negative onset potential ( E onset =‐0.16 V vs. Ag/AgCl (0.18 V vs. RHE)), which is explained by the excellent electronic properties of GF. An ORR process based in a 2‐electron mechanism is assumed for all modified electrodes. The PMo 11 V‐ and the nanocomposite‐modified electrodes are also effective for the reduction of hydrogen peroxide, with PMo 11 V@GF displaying the most promising electrocatalytic performance. The successful preparation of the nanocomposites is confirmed by X‐ray photoelectron spectroscopy and Fourier transformed infrared spectroscopy techniques. The electrochemical characterization of all modified electrodes is also reported.