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

The Ni(P2N2)2 catalysts are among the most efficient non-noble-metal based molecular catalysts for H2 cycling. However, these catalysts are O2 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 H2 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 H2 is used by the catalyst to convert O2 to H2O, thereby providing the “active” layer with a barrier against O2. 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 H2 oxidation as well as O2 tolerance. Bio-inspired Ni-based molecular catalysts are efficient for H2 oxidation, but are suffering from the poor stability in the presence of O2. Here, the authors develop a strategy to boost greatly their stability by dispersing them in a hydrophobic and redox-silent polymer matrix.