Influence of cationic structures on oxygen reduction reaction at Pt electrode in fluorohydrogenate ionic liquids

• Published in: Journal of power sources Vol. 266; pp. 193 - 197
• Main Authors: Kiatkittikul, Pisit, Yamaguchi, Jumpei, Taniki, Ryosuke, Matsumoto, Kazuhiko, Nohira, Toshiyuki, Hagiwara, Rika
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.11.2014; Elsevier
• Subjects: Applied sciences; Cationic; Diffusion coefficient; Direct energy conversion and energy accumulation; Disks; Electrical engineering. Electrical power engineering; Electrical power engineering; Electrochemical conversion: primary and secondary batteries, fuel cells; Electrodes; Energy; Energy. Thermal use of fuels; Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc; Exact sciences and technology; Fluorohydrogenate; Fuel cell; Fuel cells; Ionic liquid; Ionic liquids; Oxygen reduction reaction; Platinum; Reduction; Solubility; Fluorohydrogenate; Oxygen reduction reaction; Fuel cell; Ionic liquid; Electrodes; Chemical reduction; Oxygen; Platinum; Transition metal; Structure
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2014.05.019

Various parameters related to the oxygen reduction reaction (ORR) on a Pt electrode such as kinetically limited current density (jk), yield of H2O2 (XH2O2), and solubility (C) and diffusion coefficient (D) of oxygen were evaluated at 298 K in fluorohydrogenate ionic liquids (FHILs) using the rotating ring-disk electrode (RRDE) method. The FHILs investigated in this study were 1-ethyl-3-methylimidazolium fluorohydrogenates (EMIm(FH)1.3F and EMIm(FH)2.3F), N-ethyl-N-methyl pyrrolidinium fluorohydrogenates (EMPyr(FH)1.7F and EMPyr(FH)2.3F), trimethylsulfonium fluorohydrogenate (S111(FH)1.9F), triethyl-n-pentylphosphonium fluorohydrogenate (P2225(FH)2.1F), and 5-azoniaspiro[4.4]nonane fluorohydrogenate (AS[4.4](FH)2.0F). Among them, EMPyr(FH)1.7F showed the largest jk value (−1.5 mA cm−2) at 0.7 V vs. RHE. EMPyr(FH)1.7F, EMPyr(FH)2.3F, and P2225(FH)2.1F showed small XH2O2 values around 1.5% at a disk electrode potential of 0.2 V vs. RHE. The C and D values obtained for the FHILs were in the ranges of 0.23–1.3 mmol dm−3 and (1.1–3.2) × 10−5 cm2 s−1, respectively. The crossover currents of oxygen in the FHILs were estimated using the obtained C and D values, which were of the same order of magnitude as that for a 0.5 M H2SO4 aqueous solution. •ORR on Pt electrode was evaluated in various fluorohydrogenate ionic liquids.•The largest kinetically limited current was observed in EMPyr(FH)1.7F.•Low yield of H2O2 (about 1.9%) was observed in EMPyr(FH)1.7F.•Diffusion coefficients and solubilities of oxygen in various ionic liquids were determined.•The estimated crossover currents of oxygen were small enough for practical use.