Electrocatalytic performance of Mn-adsorbed g-C3N4: a first-principles study

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 O-2 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.

Automated summary

Single-atom catalysts with magnetic elements have been widely utilized as efficient OER electrocatalysts. By investigating the adsorption of different contents of transition metal atom Mn on g-C3N4, it was found that 2Mn-C3N4 exhibited higher OER activity and lower over-potential compared to Mn-C3N4. The metal-support interaction can influence the OER performance, with orbital hybridization intensity playing an important role in the catalytic activity.