Open AccessMixed-Valence Metal Oxide Nanoparticles as Electrochemical Half-Cells: Substituting the Ag/AgCl of Reference Electrodes by CeO2–x Nanoparticles
Author(s) -
Rajaram K. Nagarale,
Udo Hoss,
Adam Heller
Publication year - 2012
Publication title -
journal of the american chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.115
H-Index - 612
eISSN - 1520-5126
pISSN - 0002-7863
DOI - 10.1021/ja3103549
Subject(s) - nanoparticle , electrochemistry , chemistry , electrode , reference electrode , cerium oxide , valence (chemistry) , metal , oxide , inorganic chemistry , redox , working electrode , cerium , nanotechnology , chemical engineering , materials science , organic chemistry , engineering
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.