Optimization of the Activity of Cobalt Spinel Nanoparticles by N-Species of Carbonaceous Coating for Acidic Oxygen Evolution Reaction

Abstract

The development of efficient non-noble metal electrocatalysts for the oxygen evolution reaction (OER) in acidic conditions remains a critical challenge. Here, we reported a N-doped carbonaceous component-engineered Co3O4 (NCEC) catalyst synthesized by sol-gel method. The dopamine hydrochloride (DA) derived nitrogen-doped carbonaceous components were revealed for boosting the OER performance of Co3O4. The thermodynamic overpotential scales inversely with the content of oxidized-N and pyridinic-N, while it scales with the pyrrolic-N content. Moreover, a large content of oxidized-N and pyridinic-N, and a small content of pyrrolic-N were found in the samples with small DA. This can explain the low overpotential of Co3O4@C/CP-0.5mM. We also provided an interpretation of the effect of N species on the activity of Co3O4 through density functional theoretical (DFT) calculations. Our calculations demonstrated that the oxidized-N showed the smallest overpotential while the pyrrolic-N showed the largest overpotential. It was found that oxidized-N exhibited the largest G*OH. This the main reason for oxidized-N in reducing the overpotential of Co3O4. Our study implies that the performance of NCEC in acid media can be further optimized by enhancing the content of oxidized-N species.

Keywords: Co3O4, dopamine, oxidized nitrogen, acidic OER, DFT