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

Exploring SnxTi1−xO2 Solid Solutions Grown onto Graphene Oxide (GO) as Selective Toluene Gas Sensors

“…In this context and with our promising results already reported on the synergistic effect between p-type MOS and n-type graphene oxide (GO), especially in reducing the operating temperature [27,35], we believe that the Sn x Ti 1−x O 2 /GO solid solution system may be an efficient active material with even improved selectivity. Indeed, there are already several papers [36][37][38][39][40] dealing with both synthesis and successful application of SnO 2 -TiO 2 mixed oxides as either photocatalysts or sensing materials.…”

“…Graphene oxide (GO) was prepared by adopting a modified Hummers' method, already reported elsewhere [27,35]. For the solid solution Sn x Ti 1−x O 2 /GO materials, different tin(IV) chloride pentahydrate (SnCl 4 × 5H 2 O, by Sigma-Adrich, Darmstadt, Germany, 98%) contents were dissolved in 3.0 g L −1 of a 2-propanol-based (by Sigma-Aldrich, ≥95.5%) GO suspension to produce both Sn/(Sn + Ti) precursor molar ratios equal to 0.21, 0.35, 0.44, 0.55 and 0.71, and Sn + Ti salt precursors-to-GO weight ratios always of 32:1.…”

“…Powders were deposited on glass substrates topped with interdigitated Au electrodes (Au-IDEs) by a simple hot-spray method reported in our previous works [27,35]. Therefore, the tested IDEs were prepared by adopting both pristine and solid solution metal oxides.…”

“…For the gas sensing tests, two gold probes were separately placed on top of the powders covered IDEs, and the dynamic response was recorded by an electrochemical workstation (Autolab PGStat30, Ecochemie The Netherlands, potentiostat/galvanostat controlled by NOVA 2.0 software), applying a bias of +1.0 V. The sensor response is reported as: (R air /R analyte ) − 1, where R air is the film resistance in air and R analyte is the film resistance at a given concentration of the target gas [42]. As reported in our previous works [27,35], both sensors' response and recovery times have been evaluated considering the 90% of the final response.…”

“…Furthermore, BET isotherms ( Figure S1a) unveil the presence of bottle-necked pores [49], with a typical H2-type hysteresis loop for pure TiO 2 , SnO 2 and 32:1 TiO 2 /GO. However, 32:1 Sn x Ti 1−x O 2 /GO materials, along with 32:1 SnO 2 /GO, are characterized by a hysteresis loop shape between that of pure SnO 2 or TiO 2 and the one of GO [35]. Therefore, some of these powders possess bottle neck-shaped pores (typical of SnO 2 ), others slit-shaped ones (typical of GO).…”