Graphene‐Supported Substoichiometric Sodium Tantalate as a Methanol‐Tolerant, Non‐Noble‐Metal Catalyst for the Electroreduction of Oxygen

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Abstract
For the oxygen reduction reaction (ORR) in acidic medium, a good combination of an active and stable catalyst highly dispersed on a conductive and durable support is required. Moreover, for direct methanol fuel‐cell applications, a suitable tolerance to methanol poisoning is also necessary. In this communication, we report on a new graphene‐supported sodium tantalate (Na2Ta8O21−x) electrocatalyst obtained at high temperature and characterized by significant substoichiometry. The synthesis includes the precipitation of tantalum oxide on a high surface area graphene and subsequent thermal treatment at 900 °C. A novel sodium tantalate phase with oxygen vacancies is thereafter obtained. This catalyst formulation shows promising activity towards the ORR especially in the presence of a high methanol concentration, as evidenced by a high tolerance to methanol poisoning. Accelerated stress tests and chemical leaching experiments also show the remarkable stability of the catalyst. This material presents good perspectives for application in cost‐effective fuel cells.

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