High surface area carbonous components from emulsion derived SiOC and their gas sensing behavior

A commercially available liquid polysiloxane polymer was emulsified via stirring in the presence of water and surfactant. After curing, porous microbead/capsule thermosets were obtained. The samples kept their shape upon pyrolysis and resulted in SiOC ceramics which were etched by hydrofluoric acid at room temperature. The specific surface area of the components increased considerably reaching to 310 m2/g when etching process was conducted. It was shown that the samples had hierarchical porosity including micro-meso and macro porosity (5-10 micron range). The etching process affected the conductivity and the room temperature NO2 sensing capability of the SiOC samples. It is shown that porous SiOC and carboneous materials produced via hydrofluoric acid etching, can be used to detect NO2 (5 ppm) at room temperature (for the etched sample) with an easy-to-read conductance (mS range) as well as fast response kinetics (few minutes) and a complete signal recovery.