Fabricating dendritic N-C/MnOx to enable a highly efficient oxygen evolution reaction electrocatalysis

• Dendritic N-C/Mn 2 O 3 are fabricated via a facile hydrothermal and annealing method. • The introduced N-CDs are favorable for promoting charge transfer. • The N-C/Mn 2 O 3 catalyst shows excellent OER performance. Exploiting effective and low-cost electrocatalysts toward water oxidation is of vital significance for boosting overall water splitting. Herein, we proposed a simple method for constructing dendritic N-doped carbon/ manganese oxides (N-C/MnO x ) hybrid nanocomposites by annealing the composite of nitrogen-doped carbon quantum dots (N-CQDs) and γ-MnOOH (γ-MnOOH@N-CQDs) at different temperatures under N 2 /O 2 atmosphere. The obtained N-C/MnO x exhibited remarkable electrocatalytic activity and stability for oxygen evolution reaction (OER) owing to their unique dendritic structure, rich oxygen vacancies, optimized electronic structure, abundant Mn-C/N, and large electrochemical active area. Among of the prepared N-C/MnO x hybrid nanocomposites, N-C/Mn 2 O 3 showed the best performance toward OER with an overpotential of merely 347 mV to reach to 10 mA cm −2 , along with a small Tafel slope of 75.51 mV dec −1 . More remarkably, by combining Pt/C with N-C/Mn 2 O 3 for overall water splitting, a battery voltage of only 1.67 V is needed to reach the 10 mA cm −2 , rivaling the activity of the state-of-the-art IrO 2 ‖ Pt/C couple.