Atomically Engineered Cobalt-doped Boron Nitride Nanosheets for Water Oxidation Reaction

Hexagonal boron nitride (h-BN) is a fascinating two-dimensional material with a wide range of potential applications. However, its application in electrocatalysis is limited due to the lack of proper active sites and poor electrical conductivity. Herein, we introduce cobalt as a dopant into h-BN nanosheets using a controlled molten salt technique at elevated temperature. The structural and morphological analysis confirms the successful formation of h-BN and cobalt-doped BN nanosheets. The presence of cobalt in the h-BN nanosheets disrupts the extended π conjugation of h-BN by electronically interacting with B and N. While bare h-BN exhibits poor catalytic activity towards the oxygen evolution reaction (OER), cobalt doping significantly enhances its performance. The Cobalt centers serve as the active sites for OER, with the material containing 2.5 weight% Cobalt (Co2.5-BN) demonstrating optimized catalytic performance, demanding only 322 mV overpotential at 10 mA/cm2 current density along with a robust stability of 20 hours. A turnover frequency (TOF) of 1.0 s-1 at 400 mV overpotential highlights the high intrinsic activity of Co2.5-BN. The in-situ EIS analysis reveals the fast kinetics and supports the proposed equivalent electrical circuit model at the electrode/electrolyte interface. This study utilizes the structural features of h-BN material via cobalt doping towards enhanced OER catalysis.