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.

Electroosmotic Flow in Cell Built with Electrodes Having Two Redox Couples

“…5 The redox potential of 10−20 nm CeO 2−x nanoparticles is ∼0.21 V versus standard hydrogen electrode (SHE), which is nearly identical to the redox potential of the Ag/AgCl electrode. 6 The nitrogen-containing graphene oxide comprises oxidizable and reducible nitrogen functions. The proton-generating anodic electrooxidation reactions are as follows: The redox potential of 10−20 nm CeO 2−x nanoparticles is ∼0.21 V versus SHE, which is nearly identical to the redox potential of the Ag/AgCl electrode, suggesting their use as reference electrodes in subcutaneously implantable glucose sensors.…”

Mesoporous Ce2Zr2O7/PbS Nanocomposite with an Excellent Supercapacitor Electrode Performance and Cyclic Stability

“…Figure S4 a, b and c display Raman Spectra for Ce 2 Zr 2 O 7 , PbS and Ce 2 Zr 2 O 7 /PbS, respectively (SI). The sharp and dominant peak at 467 cm −1 (Figure S4a) results from the symmetrical stretching vibrational mode of [Ce–O8] . The bands at around 305 and 623 cm −1 are related to the B 1g , B 3g modes of vibration and stretching vibration mode of Zr−O in Ce 2 Zr 2 O 7 , respectively .…”

“…The sharp and dominant peak at 467 cm À 1 ( Figure S4a) results from the symmetrical stretching vibrational mode of [Ce-O8]. [41] The bands at around 305 and 623 cm À 1 are related to the B 1g , B 3g modes of vibration and stretching vibration mode of ZrÀ O in Ce 2 Zr 2 O 7 , respectively. [35] In the Raman spectrum of PbS (Figure S 4b), the peaks at around 80 and 137 cm À 1 are attributed to the longitudinal and diagonal acoustic modes, whereas those at 271 and 434 cm À 1 are linked respectively to the two-phonon process and probably 2 longitudinal optical phonon modes.…”

Electrochemical Simultaneous Sensing of Melatonin, Dopamine and Acetaminophen at Platinum Doped and Decorated Alpha Iron Oxide

“…Iron oxide nanoparticle is an n‐type semiconductor with band gap energy 2.2 eV and desired electrical and chemical properties. Its nontoxic and magnetic properties enable applications in drug delivery, biosensing, magnetic separation, magnetic resonance imaging and catalyst in electrochemical, optical, and electronic devices . Hence searching for efficient and cost effective methods for iron nanoparticle synthesis is being continued.…”