Current Oscillation during Simultaneous Reduction of Tin(II) ions, Nitrate, and Nitrobenzene at Au Electrode

#AiMES2018, Z01 General Student Poster Session.This is a slightly revised version of our presentation at AiMES 2018 in Cancun, Mexico on October 2, 2018 6:00PM (Abstract MA2018-02 2086).We have reported that NO3- is reduced efficiently at an Au electrode in the presence of Sn2+ though Au is not an excellent electrocatalyst for the reduction, and also that a nitrobenzene (NB) droplet put on the electrode moves like amoeba due to a Marangoni effect (J. Electrochem. Soc., 165, H473 (2018)). The motion occurs because Sn2+, NO3-, and NB are simultaneously reduced at the electrode. Recently, we have found that the simultaneous reduction shows a current oscillation. This present study investigates how the simultaneous reduction causes the oscillation. The nitrate reduction, which is the main current-producing reaction, includes an N-NDR characteristic that is essential for the appearance of the oscillation. The N-NDR characteristic is related to the reduction of NB to aniline. The oscillation is accompanied with a change in the optical reflectance at the electrode surface, which is attributed to a change in the amount of Sn(OH)2 precipitate near the electrode.