Mechanistic understanding on effect of doping nitrogen with graphene supported single-atom Ir toward HER and OER: A computational consideration

Abstract

The electrochemical hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) hold tremendous potential as pathways for generating clean energy. In this study, we conducted comprehensive density functional theory (DFT) calculations to investigate the influence of nitrogen (N) dopants, in terms of their types (Pyrrolic-N and Pyridinic-N) and concentrations, on the performance of 2D graphene-based catalysts containing single atoms of iridium (Ir SACs) for HER and OER. Our computational results demonstrate that the incorporation of N dopants into graphene-based supports significantly enhances the stability of Ir SACs. The bonding strength between the individual Ir atoms and the support material increases as the N content rises. Moreover, as the number of N dopants increases, the electron loss from Ir decreases. Notably, Ir-3-N1-Pi exhibits superior HER performance with a ΔGH* value of 0.24 eV, while Ir-4-N4-Po demonstrates excellent OER performance with an overpotential (η) of 0.47 V. By understanding the influence of N dopants, this study can pave the way for better tailor graphene-based catalysts for enhanced HER and OER performance, thus advancing the development of clean and sustainable energy technologies.