Redox switches for chemical detection, extraction, purification, catalysis, and data and energy storage


University of Nevada, Reno researchers Dr. Masahiro Muraoka, Dr. Stephen L. Gillett (Mackay School of Mines), and Dr. Thomas W. Bell (Department of Chemistry) have developed a redox-switchable material technology comprised of a redox-active material connected by adsorption and/or chemical bonding to a semiconductor.

Technology Summary

Redox-switchable materials consist of a redox-active part that can have its chemical charge selectively and reversibly switched between a reduced state and an oxidized state (between positive and negative charge; hence, reduction-oxidation, or redox, switchable.) As described here, the material consists of a solid semiconductor base adsorbed, bonded, or both to the redox-active component.

Redox-switchable materials can be toggled by external triggers such as light, electricity, or chemical charge, and they can in turn change their own chemical charge; they are not only switchable but work as switches themselves. Their precise sensitivity to such triggers also makes them useful for sensing small quantities of solutes, selective transport of charged particles (filtration, for example), and catalysis. They may even have applications in molecular nanotechnology as controllers for the self-assembly of molecular devices.

Existing methods for “recognizing” and extracting solutes from a solution (i.e. ion-exchange resins, zeolites, and macrocylic compounds) have been developed, but they suffer in common from an “elution problem”: the adsorber or binding agent, once saturated with the extracted component, holds on to it and makes final removal difficult and expensive. This problem could be avoided if the adsorber or binding agent could have its affinity selectively changed, triggering it to “let go” of the solute—an option that redox-switchable materials make available.

The redox-active moieties demonstrated in this technology are ferrocenes, acridines, and quinones, but other redox-active materials suffice.

Potential Applications

Because of the wide applicability inherent in controlling the charge of a solution, redox-switchable materials have an extremely wide range of applications:

  • Switchable, selective extraction of certain solutes from aqueous solutions: pollution control, water purification, desalination, hydrometallurgy
  • Selective complexation of solutes: treatment of metal intoxication, design of antibiotics that use complexation, imaging agents in the body, ion-exchange materials, hydrometallurgy, metal ion sequestering in detergents
  • Sensors for detecting small quantities of solutes: biological applications, poison/toxin detection, geological surveying, water quality measurement, product quality control
  • Photoerasable, reusable writing media or data storage: advanced computing, chemical information backup, information science
  • Photochromic or electrochromic materials (materials whose properties change on application of light or an electric field): sunglasses, molecular switches, data storage, smart glass, smart windows
  • Catalysis of reactions, especially in electrosynthesis of fuels and other materials (i.e. chemical energy storage): electrolysis of water to store energy via hydrogen and other fuels
  • Electrosorption or “artificial photosynthesis” for solar/light energy storage
  • Nanotechnology: Controlling the self-assembly of molecular devices



The University of Nevada is seeking expressions of interest from parties interested in collaborative research to further develop, evaluate, or commercialize this technology.

IP Status

UNR ID#: UNR02-002
“Redox-switchable materials”
US Patent: No. 7,435,362


Reversible Photoinsertion of Ferrocene into a Hydrophobic Semiconductor Surface: A Chemionic Switch


Patent Information:
For Information, Contact:
April Sferrazzo
Account Tech
University of Nevada, Reno and Desert Research Institute
Stephen Gillett
Thomas Bell
Masahiro Muraoka