Room Temperature\nSensing of Volatile Organic Compounds\nUsing Hybrid Layered SnO Mesoflowers and Laser-Induced Graphitic Carbon\nDevices

In this work, we demonstrate chemiresistive volatile\norganic compound\n(VOC) sensors prepared by drop-cast assembly of layered tin monoxide\nmesoflowers (SnO-MFs) on additively produced laser-induced graphene-like\ncarbon (LIG). The SnO-MFs were synthesized below 100 °C at ambient\npressure and offer a low fabrication energy alternative route to typical\nfurnace-prepared metal-oxide materials. The additive dropcast assembly\nof room-temperature operating metal oxide active material allows the\nsubstitution of LIG for metal current collectors and glass for alumina,\nreducing the environmental footprint of the sensor. The sensors can\ndetect methanol (150–4000 ppm) at room temperature and humidity\n(∼18 °C, ∼55% RH), with response and recovery times\n(150 ppm methanol) of <i>t</i><sub>90,resp</sub> ≈\n50 ± 10 s and <i>t</i><sub>90,rec</sub> ≈ 5\n± 0.5 s, respectively. The sensors demonstrated a limit of detection\n(170 ± 40 ppm) below 8 h worker safety exposure levels (200 ppm)\nand stable DC resistance responses Δ<i>R</i>/<i>R</i> = 9 ± 2% to 710 ppm of methanol for over 21 days\nin ambient laboratory conditions, <i>n</i> = 4. First-principles\ndensity functional theory simulations were used to elucidate the interactions\nof VOC species on the SnO surfaces. LIG-SnO hybrid sensors thus present\na resource-efficient route to develop chemiresistive sensors for low-power\napplications, although with cross-selectivity to other alcohol species.