title: Mixed-valence metal oxide nanoparticles as electrochemical half-cells: substituting the Ag/AgCl of reference electrodes by CeO(2-x) nanoparticles.
abstract: Cations of mixed valence at surfaces of metal oxide nanoparticles constitute electrochemical half-cells, with potentials intermediate between those of the dissolved cations and those in the solid. When only cations at surfaces of the particles are electrochemically active, the ratio of electrochemically active/all cations is ~0.1 for 15 nm diameter CeO(2-x) particles. CeO(2-x) nanoparticle-loaded hydrogel films on printed carbon and on sputtered gold constitute reference electrodes having a redox potential similar to that of Ag/AgCl in physiological (0.14 M) saline solutions. In vitro the characteristics of potentially subcutaneously implantable glucose monitoring sensors made with CeO(2-x) nanoparticle reference electrodes are undistinguishable from those of sensors made with Ag/AgCl reference electrodes. Cerium is 900 times more abundant than silver, and commercially produced CeO(2-x) nanoparticle solutions are available at prices well below those of the Ag/AgCl pastes used in the annual manufacture of ~10(9) reference electrodes of glucose monitoring strips for diabetes management.
authors.affiliation: Department of Chemical Engineering, Indian Institute of Technology, Kanpur, UP India-208016.
authors.forename: Rajaram K
authors.initials: RK
authors.lastname: Nagarale
authors.forename: Udo
authors.initials: U
authors.lastname: Hoss
authors.forename: Adam
authors.initials: A
authors.lastname: Heller
mesh_terms: D002244:Carbon / Q000737:chemistry; D002563:Cerium / Q000737:chemistry*; D055664:Electrochemical Techniques; D004566:Electrodes; D005947:Glucose / Q000032:analysis*; D053758:Nanoparticles / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*; D018030:Silver Compounds / Q000737:chemistry*
chemical_list: D018030:Silver Compounds; D002563:Cerium; D012834:Silver; C030583:ceric oxide; D002244:Carbon; D005947:Glucose; C037548:silver chloride