Carbon-Doped Boron Nitride Nanosheet: An Efficient Metal-Free Electrocatalyst for the Oxygen Reduction Reaction

Replacing precious Pt-based catalysts with cheap and earth-abundant materials to facilitate the sluggish oxygen reduction reaction (ORR) at the cathode is critical to realize the commercialization of fuel cells. In this work, we explored the potential of utilizing the experimentally available carbon (C)-doped boron nitride (BN) nanosheet as an ORR electrocatalyst by means of comprehensive density functional theory (DFT) computations. Our computations revealed that C-singly doping into h-BN nanosheets can cause high spin density and charge density and reduce the energy gap, resulting in the enhancement of O-2 adsorption. In particular, the C-N sheet (substituting N by C atom) exhibits appropriate chemical reactivity toward O-2 activation and promotes the subsequent ORR steps to take place though a four-electron OOH hydrogenation pathway with the largest activation barrier of 0.61 eV, which is lower than that of the Pt-based catalyst (0.79 eV). Therefore, the C-N-based BN sheet is a promising metal-free ORR catalyst for fuel cells.