Dual properties of a hydrogen oxidation Ni-catalyst entrapped within a polymer promote self-defense against oxygen

The Ni(P(2)N(2))(2) catalysts are among the most efficient non-noble-metal based molecular catalysts for H(2) cycling. However, these catalysts are O(2) sensitive and lack long term stability under operating conditions. Here, we show that in a redox silent polymer matrix the catalyst is dispersed into two functionally different reaction layers. Close to the electrode surface is the “active” layer where the catalyst oxidizes H(2) and exchanges electrons with the electrode generating a current. At the outer film boundary, insulation of the catalyst from the electrode forms a “protection” layer in which H(2) is used by the catalyst to convert O(2) to H(2)O, thereby providing the “active” layer with a barrier against O(2). This simple but efficient polymer-based electrode design solves one of the biggest limitations of these otherwise very efficient catalysts enhancing its stability for catalytic H(2) oxidation as well as O(2) tolerance.