In Situ Construction of Hierarchical Nanoflower-Like MnO2/Biomass-Based Boron-Doped Carbon Spheres for Oxygen Evolution Reaction

Abstract

Herein, a novel boron doped carbon sphere (BCS) and its derived MnO2 nanocomposite electrode (abbreviated as MnO2/BCS) are firstly prepared via a facile hydrothermal strategy, which was successfully confirmed via a combined characterization including SEM, TEM, EDS, FT-IR, Raman and XPS. Due to the introduction of BCS, the MnO2/BCS shows hierarchical nanoflower-like morphology with a smaller particle size and higher specific surface area than that of pristine MnO2. Importantly, the resultant MnO2/BCS with proper addition of BCS displays superior OER performance than those of the pristine MnO2. The electrochemical measurement results demonstrate that the optimal MnO2/BCS0.08 can give rise to a lowest overpotential mere 170 mV at 10 mA·cm−2, onset potential reaching 1.33 V together with smallest Tafel slope value of 31.43 mV dec−1, which can be mainly due to the higher conductivity, faster charge transfer kinetics and higher electrocatalytic active sites of the MnO2/BCS0.08 than those of other counterparts. Undoubtedly, the incorporation of BCS is mainly responsible for the enhanced electrocatalytic activity. Furthermore, the MnO2/BCS0.08 also has a prominent long-term stability in alkaline conditions. In conclusion, our present work demonstrates an effective strategy to enhance the OER performance of MnO2 by incorporation of the carbon nanomaterials.