title: An Electrochemical Sensor Based on Nanostructured Hollandite-type Manganese Oxide for Detection of Potassium Ions.
abstract: The participation of cations in redox reactions of manganese oxides provides an opportunity for development of chemical sensors for non-electroactive ions. A sensor based on a nanostructured hollandite-type manganese oxide was investigated for voltammetric detection of potassium ions. The detection is based on the measurement of anodic current generated by oxidation of Mn(III) to Mn(IV) at the surface of the electrode and the subsequent extraction of the potassium ions into the hollandite structure. In this work, an amperometric procedure at an operating potential of 0.80 V (versus SCE) is exploited for amperometric monitoring. The current signals are linearly proportional to potassium ion concentration in the range 4.97 × 10(-5) to 9.05 × 10(-4) mol L(-1), with a correlation coefficient of 0.9997.
authors.affiliation: Department of Physics, Chemistry and Biology, Faculty of Science and Technology, University of State of Sao Paulo (UNESP), Rua Roberto Simonsen 305, CEP 19060-900 Presidente Prudente - SP, Brazil; E-Mails:  silvalima_alex@yahoo.com.br ;  homago@fct.unesp.br.
authors.forename: Alex S
authors.initials: AS
authors.lastname: Lima
authors.forename: Nerilso
authors.initials: N
authors.lastname: Bocchi
authors.forename: Homero M
authors.initials: HM
authors.lastname: Gomes
authors.forename: Marcos F S
authors.initials: MF
authors.lastname: Teixeira