Charge-compensated co-doping of graphdiyne with boron and nitrogen to form metal-free electrocatalysts for the oxygen reduction reaction

The development of metal-free catalysts for the oxygen reduction reaction (ORR) is critical for rechargeable metal-air batteries and full cells. Various light non-metallic-atom-doped graphdiyne (GDY) materials have been designed based on density functional theory and evaluated as efficient ORR electrocatalysts. Volcano curve correlations between the overpotential and Gibbs adsorption free energies of oxygenated intermediates have been derived for the ORR. Optimized compensated B,N co-doped GDY monolayers exhibit the lowest ORR overpotential of 0.57 V. In compensated B,N co-doped GDY, the B atoms are positioned in the benzene rings, and the N atoms are positioned in the acetylene linkages. Moreover, some B,N co-doped GDYs have two active sites with almost the same catalytic activity: the B atom and the C atom bearing an effective positive charge nearest to the doped N atom. Based on the theoretical analysis, ideal doped GDY monolayers are expected to exhibit comparable catalytic activity to Pt-based catalysts.