RuO2 nanoparticles supported on MnO2 nanorods as high efficient bifunctional electrocatalyst of lithium-oxygen battery. (October 2016)

• Record Type: Journal Article
• Authors: Xu, Yue-Feng; Chen, Yuan; Xu, Gui-Liang; Zhang, Xiao-Ru; Chen, Zonghai; Li, Jun-Tao; Huang, Ling; Amine, Khalil; Sun, Shi-Gang
• Is Part Of: Nano energy. Volume 28(2016:Oct.)
• Page Start: 63
• Page End: 70
• Publication Date: 2016-10
• Subjects: RuO2 nanoparticles on MnO2 nanorods -- Bifunctional electrocatalysts -- ORR -- OER -- Lithium-oxygen battery; Nanoscience -- Periodicals; Nanotechnology -- Periodicals; Nanostructured materials -- Periodicals; Power resources -- Technological innovations -- Periodicals; Nanoscience; Nanostructured materials; Nanotechnology; Power resources -- Technological innovations; Periodicals; 621.042
• DOI: 10.1016/j.nanoen.2016.08.009
• Languages: English
• ISSNs: 2211-2855

Abstract

Abstract: RuO2 nanoparticles supported on MnO2 nanorods (denoted as np-RuO2 /nr-MnO2 ) were synthesized via a two-step hydrothermal reaction. SEM and TEM images both illustrated that RuO2 nanoparticles are well dispersed on the surface of MnO2 nanorods in the as-prepared np-RuO2 /nr-MnO2 material. Electrochemical results demonstrated that the np-RuO2 /nr-MnO2 as oxygen cathode of Li–O2 batteries could maintain a reversible capacity of 500 mA h g −1 within 75 cycles at a rate of 50 mA g −1, and a higher capacity of 4000 mA h g −1 within 20 cycles at a rate as high as 200 mA g −1 . Moreover, the cell with the np-RuO2 /nr-MnO2 catalyst presented much lower voltage polarization (about 0.58 V at a rate of 50 mA g −1 ) than that measured with only MnO2 nanorods during charge/discharge processes. The catalytic property of the np-RuO2 /nr-MnO2 and MnO2 nanorods were further compared by conducting studies of using rotating disk electrode (RDE), chronoamperommetry and linear sweep voltammetry. The results illustrated that the np-RuO2 /nr-MnO2 exhibited excellent bifunctional electrocatalytic activities towards both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Furthermore, in-situ high-energy X-ray diffraction was employed to trace evolution of species on the np-RuO2 /nr-MnO2 cathode during the discharge processes. In-situ XRD patterns demonstrated the formation process of the discharge products that consisted of mainly Li2 O2 . Ex-situ SEM images were recorded to investigate the morphology and decomposition of the sphere-like Li2 O2, which could be observed clearly after discharge process, while are decomposed almost after charge process. The excellent electrochemical performances of the np-RuO2 /nr-MnO2 as cathode of Li–O2 battery could be contributed to the excellent bifunctional electrocatalytic activities for both the ORR and OER, and to the one-dimensional structure which would benefit the diffusion of oxygen and the storage of Li2 O2 in the discharge process of Li–O2 battery. Graphical abstract: Highlights: The np-RuO2 /nr-MnO2 were firstly synthesized via a two-step hydrothermal reaction. The np-RuO2 /nr-MnO2 as cathode of Li–O2 battery exhibits high bifunctional electrocatalytic activity. In-situ synchrotron HEXRD illustrated the formation process of Li2 O2 .