Supercritical Fluids Synthesis of Catalyst Nanoparticles- Decorated Nanocarbon for Low Concentration Formaldehyde Sensing

Abstract

The formaldehyde (HCHO) is one of a major pollutants in indoor air and it is harmful to healthy even exposed in low concentration. It was regulated that the HCHO concentration should beyond 0.08 ppm[1]. The conventional methods to analyses formaldehyde are GC, HPLC and so on, but those methods are not user friendly. We aimed to develop an electrochemical formaldehyde sensor which is highly sensitive, quick response, cost effective and user friendly. In the previous study, platinum electrocatalyst has wildly applied for the catalytic oxidation of HCHO [2]. Furthermore, some other catalysts such as palladium and copper oxide were used as oxidation catalysts. In this study, the no surface tension property of supercritical fluids were exploited to decorate nanocatalyst onto nanocarbons uniformly. The surface morphology and chemical structure of the materials were characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectrometer (FTIR), respectively. The bimetallic electrocatalyst decorated nanocarbon exhibited highly catalytic properties, and the oxidation potential could be less than 0.2 V vs. Ag/AgCl. The sensor showed a wide sensing range from 0-100 ppm and the lower detection limit was 1 ppb. All sensing properties of this HCHO sensor, including sensitivity, stability and repeatability were examined carefully. The selectivity to the potential interferences and the temperature effect were accessed. The experimental results demonstrate high feasibility of this nanocarbon-based HCHO sensor for the indoor air quality monitoring.