High-performance amperometric carbon monoxide sensor based on a xerogel-modified PtCr/C microelectrode

Abstract

An amperometric biosensor based on a xerogel-modified PtCr/C microelectrode was developed for direct carbon monoxide (CO) detection. The effects of elemental Cr on the structural and electronic characteristics of the binary PtCr/C catalyst were characterized using various analytical techniques. Differential pulse voltammetry and amperometric measurements were performed to evaluate the electrocatalytic performance of the fabricated electrodes with respect to CO oxidation. The modified PtCr/C catalyst showed significantly improved electrocatalytic activity for CO oxidation, including a low applied potential of 0.3 V (vs. Ag/AgCl, high sensitivity of 12.5 nA μM−1 (standard deviation [SD] 0.52 nA μM−1)), excellent surface sensitivity of 726.6 nA μM−1 cm−2 (SD 30.4 nA μM−1 cm−2), and sufficiently high CO selectivity in the presence of other common metabolites. Modification of the PtCr/C-alloy catalyst surface with a fluorinated xerogel membrane minimized the effects of interfering species. Under optimal conditions, the xerogel-modified PtCr/C microelectrode exhibited a CO sensitivity of 8.82 nA μM−1 (SD 0.08 nA μM−1) and corresponding selectivity (logKCO,iamp) of < −5, −2.82 (SD 0.38), −3.16 (SD 0.03), − 2.57 (SD 0.05), −0.99 (SD 0.01), −2.02 (SD 0.01), and −1.79 (SD 0.05) for nitrite, ascorbic acid, uric acid, acetaminophen, dopamine, hydrogen peroxide, and nitric oxide. The xerogel-modified PtCr/C sensor was used to measure the CO directly generated on the surface of a living kidney in real time, and a CO concentration of 0.74 μM was estimated. Thus, our sensor can serve as a novel platform for developing high-performance electrochemical sensors suitable for practical applications.