Journal of Materials Research

Articles

A room-temperature TiO2-nanotube hydrogen sensor able to self-clean photoactively from environmental contamination

Gopal K. Mora1, Maria A. Carvalhoa2, Ooman K. Varghesea3, Michael V. Pishkoa4 and Craig A. Grimesa5 c1

a1 Department of Electrical Engineering and Department of Materials Science and Engineering, 217 Materials Research Laboratory, The Pennsylvania State University, University Park, Pennsylvania 16802

a2 Department of Chemical Engineering, 267 Materials Research Laboratory, The Pennsylvania State University, University Park, Pennsylvania 16802

a3 Department of Electrical Engineering and Department of Materials Science and Engineering. 217 Materials Research Laboratory, The Pennsylvania State University, University Park, Pennsylvania 16802

a4 Department of Chemical Engineering, 267 Materials Research Laboratory, The Pennsylvania State University, University Park, Pennsylvania 16802

a5 Department of Electrical Engineering and Department of Materials Science and Engineering, 217 Materials Research Laboratory, The Pensylvania State University, University Park, Pennsylvania 16802

Abstract

Described is a room-temperature hydrogen sensor comprised of a TiO2-nanotube array able to recover substantially from sensor poisoning through ultraviolet (UV) photocatalytic oxidation of the contaminating agent; in this case, various grades of motor oil. The TiO2 nanotubes comprising the sensor are a mixture of both anatase and rutile phases, having nominal dimensions of 22-nm inner diameter, 13.5-nm wall thickness, and 400-nm length, coated with a 10-nm-thick noncontinuous palladium layer. At 24 °C, in response to 1000 ppm of hydrogen, the sensors show a fully reversible change in electrical resistance of approximately 175,000%. Cyclic voltammograms using a 1 N KOH electrolyte under 170 mW/cm2 UV illumination show, for both a clean and an oil-contaminated sensor, anodic current densities of approximately 28 mA/cm2 at 2.5 V. The open circuit oxidation potential shows a shift from 0.5 V to −0.97 V upon UV illumination.

(Received August 14 2003)

(Accepted November 13 2003)

Key Words:

  • Surface reaction;
  • Ceramic;
  • Chemical reactivity

Correspondence:

c1 Address all correspondence to this author. e-mail: cgrimes@engr.psu.edu

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