Electrocatalytic performance of Mn-adsorbed g-C3N4: a first-principles study†
Abstract
Single-atom catalysts with magnetic elements as the active center have been widely exploited as efficient oxygen evolution reaction (OER) electrocatalysts. Here, different contents of transition metal atom Mn adsorbed on graphitic carbon nitride (g-C3N4) were investigated for OER properties by first-principles calculations. Based on the Gibbs free energy, 2Mn–C3N4 possesses higher OER properties, and has a lower over-potential (1.22 V) than Mn–C3N4 (2.42 V). 2Mn–C3N4 has moderate absorption energies for OH and OOH, which benefits the first one-electron reaction and the O2 desorption during the OER. Additionally, by analyzing the partial density of states and projected crystal orbital Hamilton population, the anti-bonding states become less occupied and the adsorption strength of OH is enhanced in 2Mn–C3N4. Thus, the adsorptive strength of 2Mn–C3N4 for OH is stronger than that of Mn–C3N4, which causes 2Mn–C3N4 to show a higher OER activity. The metal–support interaction can alter the local electronic characteristics. The interaction between the metal active center and the reaction intermediates can influence the OER performance, where the specific orbital hybridization plays an important role. Therefore, our results provide a primary understanding of the influence of orbital hybridization intensity on effective OER catalysts.