Characteristic evaluation of pencil-drawn carbon electrode by potassium and sodium ion selectivity measurement and energy-dispersive X-ray spectroscopy

• Published in: Japanese Journal of Applied Physics Vol. 59; no. 4; pp. 47001 - 47007
• Main Authors: Kawahara, Ryotaro, Kamahori, Masao, Murase, Naoya, Goto, Tomotaka, Minemoto, Takashi, Uno, Shigeyasu
• Format: Journal Article
• Language: English
• Published: Tokyo IOP Publishing 01.04.2020; Japanese Journal of Applied Physics
• Subjects: Aluminum; Carbon; Cation exchanging; Dispersion; Electrical conduction; Electrodes; Energy dispersive X ray spectroscopy; Evaluation; Ion exchange; Ion exchangers; paper electronics; pencil-drawn carbon electrode; pH selectivity; pH sensor; Selectivity; Silicon; Sodium; Spectrum analysis
• ISSN: 0021-4922; 1347-4065
• DOI: 10.35848/1347-4065/ab7864

This paper explains the ion-sensing mechanism and selectivity evaluation of the pencil-drawn carbon electrode (PCE) employed as a pH electrode in the authors' previous report. The elemental composition of the PCE was found to be C, O, Si, Al, and Na by energy-dispersive X-ray spectroscopy (EDX). The carbon is regarded as the graphite performing electrical conduction, while the other elements formed clay as an ion exchanger. Furthermore, the potential responses to K+ and Na+ were measured, and the selectivity is discussed quantitatively under the Eisenman equation which describes the ion exchanger potential with cation interference. The selectivity coefficients were estimated to be 10−4.10 to 10−3.87 and 10−5.00 to 10−4.89 for K+ and Na+ with n of 4 to 5, respectively. The EDX analysis and selectivity measurement show that the PCE might have ion exchange properties similar to those of a glass electrode and it sufficiently behaves as a pH electrode in wide targets having only slightly interfering cations.