Direct electrochemical sensing of ethanol gas by utilizing air/water interface at platinum nanohole array electrode.

This study demonstrated direct electrochemical ethanol gas sensing using the air/water interface of a platinum nanohole array (PtNH) electrode. The sensing unit comprised a PtNH electrode deposited on a hydrophobized porous anodic alumina (PAA) membrane, and the sensing unit was fixed at the open window on the side of the plastic container with an internal solution containing 3 M NaCl and 100 mM phosphate buffer (pH 8.5). Since an air/water interface was formed at the PtNH, the ethanol gas that passed through the cylindrical pores of the alumina (200 nm in diameter) could be detected electrochemically using the PtNH. In chronoamperometry measurements, the peak current of the oxidation of ethanol was proportional to the ethanol gas concentration in the concentration range of 10 ppm or less. The detection limit of the proposed sensor was 0.84 ppm, and the sensor sensitivity was 6.7 µA cm− 2 ppm–1.