Hydrothermally grown uniform sized nickel hydroxide/oxyhydroxide hexagonal nanoprisms exhibiting room temperature ethanol sensing properties

This work reports a simple hydrothermal method for the synthesis of uniform sized hexagonal nanoprisms (similar to 38 nm) of beta-nickel hydroxide/oxyhydroxide that show room temperature ethanol sensing properties. The films made of these nanoprisms show response as high as 120 against 100 ppm ethanol vapour at room temperature with good repeatability over several cycles and fast response and recovery times of 2 s and 17 s, respectively. The films of nanoprisms also show high selectivity to ethanol vapour as evident from their almost negligible responses to other alcohol vapors and non-alcoholic vapors tested in this work. What is unique about the material is that it shows no degradation in performance with aging and humidity; rather shows an improved response and selectivity to ethanol at 75% relative humidity. The enhanced performance is explained in terms of the special surface properties of the nanoprisms that can adsorb excess oxygen via oxyhydroxide formation and large surface area as confirmed by photoemission and surface adsorption studies. Further, the change in infrared absorption intensity is measured to understand the decomposition reaction of ethanol on the nanoprism surface. Thus, the synthesized material shows enormous promise as a low-cost material for room temperature ethanol sensing.