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

Abstract

The major drawback of oxide-based sensors is the lack of selectivity. In this context, Sn x Ti 1−x O 2 /graphene oxide (GO)-based materials were synthesized via a simple hydrothermal route, varying the titanium content in the tin dioxide matrix. Then, toluene and acetone gas sensing performances of the as-prepared sensors were systematically investigated. Specifically, by using 32:1 SnO 2 /GO and 32:1 TiO 2 /GO, a greater selectivity towards acetone analyte, also at room temperature, was obtained even at ppb level. However, solid solutions possessing a higher content of tin relative to titanium (as 32:1 Sn 0.55 Ti 0.45 O 2 /GO) exhibited higher selectivity towards bigger and non-polar molecules (such as toluene) at 350 • C, rather than acetone. A deep experimental investigation of structural (XRPD and Raman), morphological (SEM, TEM, BET surface area and pores volume) and surface (XPS analyses) properties allowed us to give a feasible explanation of the different selectivity. Moreover, by exploiting the UV light, the lowest operating temperature to obtain a significant and reliable signal was 250 • C, keeping the greater selectivity to the toluene analyte. Hence, the feasibility of tuning the chemical selectivity by engineering the relative amount of SnO 2 and TiO 2 is a promising feature that may guide the future development of miniaturized chemoresistors.

Engineering of SnO2–Graphene Oxide Nanoheterojunctions for Selective Room-Temperature Chemical Sensing and Optoelectronic Devices

“…Notably, graphene materials possess several promising features such as thermoelectric conductivity and mechanical strength, which can enhance the sensing behavior of MOS by formation of nanoscale heterojunctions. Reduced graphene oxide (rGO) has been widely investigated for electrochemical applications and offers some potential for gas sensing. − For instance, Meng et al recently described a ternary sensing materials made of ZnO–rGO sensitized with graphitic carbon nitride that exhibits superior ethanol vapor sensing, reaching a 9-fold higher response than pure ZnO. Similarly, a newly ternary nanocomposite material comprising Au, SnO 2 , and rGO has been reported to successfully detect low ppm concentrations of ethanol at OT down to 50 °C.…”

Facile Fabrication of Hybrid Carbon Nanotube Sensors by Laser Direct Transfer

“…Although we could have applied different remedies to achieve full reversibility, i.e., heating or UV exposure of the SWCNT sensors, we noticed that these treatments led to a high baseline noise, and therefore, we looked into the direction of noncovalent SWCNT functionalization by decorating the SWCNTs with metal oxide nanoparticles (SnO 2 ). In particular, the strategy of introducing active sites with strong affinities has been followed previously in order to improve sensor sensitivity [23,24].…”

Disclosing the Sensitivity and Selectivity of Metal Oxide/Graphene Oxide-Based Chemoresistors towards VOCs

“…Four different n-type semiconductors, namely WO 3 , ZnO, SnO 2 , and Sn 0.55 Ti 0.45 O 2 solid solution, were chosen to be grown onto graphene oxide (GO) material by following a very easy hydrothermal method already reported in our previous works [4][5][6][7][8]. According to earlier studies, we adopted 32:1 salt precursor-to-GO weight ratio, since it resulted in being the optimal one in terms of sensing performances at low operating temperatures.…”

“…A final calcination step at 350 • C for 1 h was performed to guarantee good powder film adhesion on IDEs. Sensing measurements were performed, adopting the chamber already described elsewhere [7]. Four different VOCs, i.e., ethanol, acetone, ethylbenzene, and toluene, were investigated as the analyte species.…”