An electrochemical outlook upon the gaseous ethanol sensing by graphene oxide-SnO2 hybrid materials

Breakthroughs in the synthesis of hybrid materials have led to the development of a plethora of chemiresistors that could operate at lower and lower temperatures. Herein, we report the fabrication of novel composite ma- terials (SnO2-GO 4:1, 8:1 and 16:1) based on graphene oxide (GO) sheets decorated with tin dioxide nano- particles, through a controlled chemical growth. We succeeded in obtaining widely spaced isles of the metal oxide on the carbonaceous material, thus enhancing the electron transfer process (i.e. favored convergent dif- fusion, as investigated through cyclic voltammetric analysis), which plays a pivotal role for the final sensing behavior. Indeed, only with SnO2-GO 16:1 sample, superior responses towards gaseous ethanol were observed both at 150 \ub0C and at RT (by exploiting the UV light), with respect to pristine SnO2 and mechanically prepared SnO2(16)@GO material. Particularly, an improvement of the sensitivity (down to 10 ppb), response and recovery times (about of 60\u201370 s) was assessed. Besides, all the powders were finely characterized on structural (XRPD, FTIR and Raman spectroscopies), surface (active surface area, pores volume, XPS), morphological (SEM, TEM) and electrochemical (cyclic voltammetries) points of view, confirming the effective growth of SnO2 nano- particles on the GO sheets