Self-templated formation of hierarchical hollow β-MnO2 microspheres with enhanced oxygen reduction activities

• Published in: Colloids and surfaces. A, Physicochemical and engineering aspects Physicochemical and engineering aspects, 2022-03, Vol.637, p.128228, Article 128228
• Main Authors: Cheng, Gao, Liu, Peng, Chen, Shihong, Wu, Yanxue, Huang, Leheng, Chen, Meijie, Hu, Chengjun, Lan, Bang, Su, Xiaohui, Sun, Ming, Yu, Lin
• Format: Article
• Language: English
• Subjects: Hierarchical hollow microsphere; Hydrothermal; Oxygen reduction reaction; Self-templated process; β-MnO2
• ISSN: 0927-7757; 1873-4359
• DOI: 10.1016/j.colsurfa.2021.128228

Herein, hierarchical hollow β-MnO2 microspheres assembled by nanorod subunits are facilely fabricated using a one-step hydrothermal approach, which serve as electrocatalyst for oxygen reduction reaction (ORR). The influences of the reaction temperature and H2SO4 concentration on the crystalline phase and morphology of products are studied. Impressively, detailed characterizations reveal that the hollow β-MnO2 microspheres can be formed through a self-templated process by phase transformation, in which solid γ-MnO2 microspheres are first generated and then convert to hollow β-MnO2 microspheres. Owing to their unique hollow shape and robust O2 adsorption ability, the hollow β-MnO2 microspheres show superior ORR performance (a more positive half-wave potential of ~ 0.69 V, a larger limiting current density of 5.04 mA cm−1, and better stability) compared with commercial β-MnO2 particles. The insights afforded in this study offer positive guidance for the rational design of hollow Mn-based materials. Hierarchical hollow β-MnO2 microspheres were formed through a self-templated process by phase transformation, exhibiting enhanced electrocatalytic performance for ORR. [Display omitted] •Hierarchical hollow β-MnO2 microspheres constructed by nanorod are facilely prepared using a one-step hydrothermal approach.•The influences of reaction temperature and H2SO4 concentration on the phase and morphology of products are studied.•The formation of hollow β-MnO2 microspheres is through a novel self-templated process.•Hollow β-MnO2 microspheres deliver superior oxygen reduction reaction activity than that of commercial β-MnO2 particles.•Enhanced catalytic activity is due to unique shape of hollow microsphere and robust O2 adsorption ability.