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A single-step electrophoretic deposition (EPD) process is used to fabricate catalyst layers which consist of nickel oxide nanoparticles attached on the surface of nanographitic flakes. Magnesium ions present in the colloid charge positively the flake's surface as they attach on it and are also used to bind nanographitic flakes together. The fabricated catalyst layers showed a very low onset voltage (-0.2 V vs Ag/AgCl) in the electro-oxidation of ethanol. To clarify the occurring catalytic mechanism, we performed annealing treatment to produce samples having a different electrochemical behavior with a large onset voltage. Temperature dependence measurements of the layer conductivity pointed toward a charge transport mechanism based on hopping for the nonannealed layers, while the drift transport is observed in the annealed layers. The hopping charge transport is responsible for the appearance of the low onset voltage in ethanol electro-oxidation.

In order to improve the performance of gas sensors based on ZnO nanoparticles, platinum was deposited on the nanoparticle surface using sputtering. Gas‐sensing experiments on Pt‐functionalized ZnO nanoparticles exhibited larger response to ethanol gas at lower operating temperature, attributed to the sensitization and spillover effects. The faster recovery time of Pt‐decorated ZnO nanoparticles is associated with the catalyst effect of Pt. The maximum sensitivity of Pt‐decorated ZnO nanoparticles was more than twice compared to that of bare ZnO nanoparticles. At 400 °C, the response time of Pt‐decorated ZnO nanoparticles to 15 ppm ethanol vapor was 150 s, while that of bare ZnO nanoparticles was of about 1200 s. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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