Stable and boosted oxygen evolution efficiency of mixed metal oxide and borate planner heterostructure over heteroatom (N) doped electrochemically exfoliated graphite foam

Abstract

Support-catalyst interface plays a critical role in electrocatalytic processes as the rates of involved reactions are directly linked with the interfacial charge transfer efficiency. Here, we are presenting nitrogen doped exfoliated graphite foil (NGF) as the 3D support which offers electronically coupled interface to catalytic heterostructure comprises of nickel-iron based oxide and its borate. As developed hybrid (NGF/NiFe/Borate) show excellent oxygen evolution reaction (OER) under alkaline condition with low overpotential of 281 mV at current density of 10 mA cm−2 and Tafel slope 62 mv dec−1. The results beat most nonprecious metal catalysts and noble commercial IrO2 deposited over same NGF substrate with outstanding long-term durability over 10 h at high current density 300 mA cm−2. Efficient electron injection from NGF support and its low resistance leads to enhancement in current density by more than 136 % at operative potential of 1.55 V, in comparison to un-doped exfoliated graphite foil support. Beside electronically tuned support, high catalytic efficiency is also linked with planner growth of borate nanosheets that helps in fast interfacial charge transfer in its transverse direction to the catalytic site. Our work highlights the importance of electronic tuning of catalyst support to enhance the performance of supported borate catalyst and to rationally design low cost, highly active OER catalyst.