Indirect boron doping enhances bifunctional oxygen electrocatalytic performance in CoN4-CNT single-atom catalysts: a DFT study

Abstract

The aim of this study is to investigate the effect of indirect boron doping on the bifunctional oxygen electrocatalytic performance of CoN₄-carbon nanotube (CNT) single-atom catalysts via density functional theory (DFT) calculations. Substituting carbon atoms adjacent to the CoN₄ active center with boron effectively preserves the coordination structure while enhancing thermodynamic stability. The optimized CoN₄B1-CNT configuration exhibits outstanding bifunctional activity, achieving low overpotentials of 0.38 V for the oxygen reduction reaction (ORR) and 0.38 V for the oxygen evolution reaction (OER), with a total energy barrier (ΔE) of only 0.76 V, surpassing most reported bifunctional catalysts. Projected density of states (PDOS) and crystal orbital Hamilton population (COHP) analyses reveal that near the Fermi level, effective d–p orbital hybridization occurs between B atoms and metallic active sites, resulting in a smoother and more continuous PDOS distribution. The integrated COHP (ICOHP) value of the modified catalyst system CoN₄B1-CNT is −2.84 eV, indicating more stable bonding. This study clarifies the intrinsic mechanism of boron doping and provides theoretical guidance for the rational design of high-performance non-precious metal bifunctional electrocatalysts.