Implications of boron doping on electrocatalytic activities of graphyne and graphdiyne families: a first principles study

Dispersive force corrected density functional theory is used to map the oxygen reduction reaction (ORR) kinetics of six kinds of graphyne (Gy) and graphdiyne (Gdy) systems (namely alpha Gy, beta Gy, gamma Gy, delta Gy, 6,6,12Gy, RGy and Gdy) with substitutional boron (B) atom doping. To this end, the most favorable sites for B doping of each structures are determined by comparing their formation energies and then the best configuration for di-oxygen (O-2) adsorption is computed by analyzing the corresponding adsorption energies. Even though oxygen adsorption is found to be energetically favorable on all of these and all Gys and Gdy are found to distinctly favor the four electron pathways for ORR, a reaction scheme with monotonically exothermic Delta G is observed only for B doped RGy. Further computations performed by varying electrode potential indicated this monotonically exothermic nature of the Delta G of B doped RGy to persist in the range 0-0.22 V and also indicated the first (H+ + e) transfer step to be the rate limiting step.