Abstract

DING, K.; WANG, Q.  and  ZHAO, M.. Cyclic Voltammetric Investigation on the Catalysis of Electrodeposited Manganese Oxide on the Electrochemical Reduction of Oxygen (ORR) in Room Temperature Ionic Liquids (RTILs) of 1-Ethyl-3-Methylimidazolium Tetrafluorobroate (EMIBF₄) on Glass Carbon (GC) Electrode. Port. Electrochim. Acta [online]. 2007, vol.25, n.3, pp.335-348. ISSN 0872-1904.

In this preliminary work, for the first time, the electrochemical oxygen reduction reaction (ORR) was investigated using cyclic voltammetry (CV) on the electrodeposited manganese oxide (MnO_x)-modified glass carbon electrode (MnO_x-GC) at room temperature ionic liquids (RTILs) of EMIBF₄, i.e., 1-ethyl-3-methylimidazolium tetrafluorobroate (EMIBF₄). The results demonstrated that, after being modified by MnO_x on GC, the reduction peak current of oxygen was increased to some extent, while the oxidation peak current, corresponding to the oxidation of superoxide anion, O₂^-, was attenuated in some degree, suggesting that MnO_xcatalyzed ORR in RTILs of EMIBF₄, which is consistent with the results obtained in aqueous solution. To accelerate the electron transfer rate, multi-walled carbon nanotubes (MWCNTs) were modified on GC, and then MnO_x was electrodeposited onto the MWCNTs-modified GC electrode to give rise to the MnO_x /MWCNTs-modified GC electrode; consequently, the improved standard rate constant, κ_s,originated from the modified MWCNTs, along with the modification of electrodeposited MnO_x, showed us a satisfactory electrocatalysis for ORR in RTILs of EMIBF₄. In addition, not only for the MnO_x-modified GC but also for the MnO_x/ MWCNTs-modified GC, there is a novel small oxidation peak appearing at -0.2 V vs. solid Ag/AgCl, implying that the catalysis of MnO_x for ORR in EMIBF₄ is somewhat different from that observed in aqueous solution, though the exact interpretation is not achieved in this preliminary work. Initiating the catalysis of MnO_xon ORR in RTILs is the main contribution of this work. Further discussions are in progress.

Keywords : manganese oxide (MnO_x); multi-walled carbon nanotubes (MWCNTs); room temperature ionic liquids (RTILs); electrochemical oxygen reduction reaction (ORR); glass carbon (GC) electrode.

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