Thick films ethanol sensors were prepared. The composition of the electrode was measured qualitatively to consist of Ni, O, Al, Mg and Pb. Among these composing elements, it was found that only the nickel could sense the ethanol. Both the infrared (IR) spectrum and cyclic voltammetry (CV) tests were employed to investigate its derivatives in the sensing reaction. It was found that the derivatives presented as adsorbed enol group and b-ketoaldehyde as enols. Besides, both the redox between Ni(II) and Ni(III), and solid-state electrochemical reactions in the electrode were found to occur in this system simultaneously. A linear dependence of response current vs. ethanol concentration with a detection limit of 37 ppm was obtained and the response time was estimated to be 140 seconds in this sensing system.

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Electroless Co-doped sensors with good coverage were prepared to investigate their microstructure variation. The phases of the deposited electrodes were identified to be Ni and β­normalNifalse(OH)2, respectively. Scanning electron microscopy was employed to observe the morphology evolution for various values of deposition time. According to the peak intensity of the energy dispersive spectrum and the composition change of the deposited film, the growth phenomena of the deposited film were obtained. A hardball model was constructed to describe the microstructure variation of this electrode. Nevertheless, this model was utilized to deduce the ethanol sensing mechanism. It was found that the response current for the ethanol was mainly contributed from that of β/β rather than α/γ and its sensitivity depended on the competition between the γ phase and β phase. Besides, the deterioration of the stability for sensitivity resulted from the decay in the phase ratio of the β-NiOOH to γ-NiOOH during charging. © 2002 The Electrochemical Society. All rights reserved.

The nanoparticles of tin-silver solder, Sn-3.5Ag, of necklace geometry were made in a swirl batch. It was found that the addition of the element, Ag, did not vary the microstructure of the solder matrix, but Ag simply diluted into the Sn matrix randomly. The swirl flow facilitated the formation of particles with different sizes. It was found that the size distribution of the nanoparticles was strongly related to the height in the swirl batch. In addition, the aggregation of the nanoparticles was explored and the dispersion of the nanoparticles was achieved by adjusting the pH value of the solution near the neutral value