SnO₂ quantum dots dispersed TGCN nanosheets for improved ethanol sensing under ambient conditions

Abstract This study investigates ethanol sensing properties of a hybrid sensing material prepared by mechano-mixing of tin oxide (SnO 2 ) quantum dots (SQDs) and template-free graphitic carbon nitride (g-C 3 N 4 ) i.e. TGCN nanosheets (TNSs). Hybrid sensors comprising of various weight ratios of TNSs and SQDs ranging from 1:5 to 1:50 (T-SX where X denotes the proportion of SQDs) were prepared and tested for ethanol vapor sensing under ambient conditions. Structural, thermal, optical, and morphological properties of the hybrid samples were analyzed comprehensively using techniques such as x-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), UV–visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), and Raman microscopy. The results indicate that the SQDs crystallize in rutile crystal structure with an average diameter of ∼ 2.7 nm and are dispersed on the TNSs. The best response and recovery time were observed for T-S20 with a fast response time of 12 ± 3 s and recovery time of 20 ± 3 s under ambient conditions. The hybrid sensor showed a 48% faster response time, and 57% faster recovery time as compared to pure quantum dots. This improvement is attributed to dispersed SQDs on TNSs, optimum bond strength between SQDs and TNSs, surface plasmon states of SQDs, higher surface area of TNSs, catalytic activity of N-atoms and finally the heterojunction formed between SnO 2 quantum dots and TNSs which attracts bipolar hyroxyl group of ethanol vapors under ambient conditions and aids in their faster detection.