Publication

Voltammetric pH Nanosensor

Author(s): Michalak, Magdalena and Kurel, Malgorzata and Jedraszko, Justyna and Diana and Wittstock, Gunther and Opallo, Marcin and Nogala, Wojciech
Title: Voltammetric pH Nanosensor
Abstract: Nanoscale pH evaluation is a prerequisite for understanding the and phenomena occurring at solid-liquid, liquid-liquid, and interfaces, e.g., heterogeneous catalysis, extraction, and corrosion. Research on the homogeneous processes small volumes such as intracellular fluids, microdroplets, and chips also requires nanometer scale pH assessment. Due to opacity of numerous systems, optical methods are useless and, if require addition of a pH-sensitive dye. Potentiometric suffer from many drawbacks such as potential drift and lack of Here, we present a voltammetric nanosensor for reliable pH between pH 2 and 12 with high spatial resolution. It consists a pyrolytic carbon nanoelectrode obtained by chemical vapor (CVD) inside a quartz nanopipette. The carbon is modified by of syringaldazine from its ethanolic solution. It exhibits a quasi-reversible cyclic voltammogram with nearly Nernstian of midpeak potentials (-54 mV/pH). This sensor was applied as probe for scanning electrochemical microscopy (SECM) in order to map over a platinum ultramicroelectrode (UME), generating hydroxide ions by the oxygen reduction reaction (ORR) at a diffusion-controlled in aerated phosphate buffered saline (PBS). The results reveal the of the electrolyte close to the oxygen reducing electrode, the insufficient buffer capacity of PBS to maintain a stable pH at the given conditions.
Pages: 11641-11645
Journal: ANALYTICAL CHEMISTRY
Publisher: AMER CHEMICAL SOC
Addres: 1155 16TH ST, NW, WASHINGTON, DC 20036 USA
Volume: 87
ID: ISI:000365931100008
Year: 2015
DOI: 10.1021/acs.analchem.5b03482