Hydrothermal Synthesis of SnO2 with Different Morphologies as Sensing Materials for HCHO Detection

Morphology regulation is an effective strategy for improving the sensor sensitivity of transition metal oxide nanostructures. In this work, SnO₂ with three different morphologies (nanorods, nanoparticles, and nanopillars) has been synthesized by a simple one-step solvothermal process with the addition of various solute ratios at 180 °C for 6 h for detecting formaldehyde (HCHO) at the optimum working temperature of 320 °C. Compared to nanorods and nanopillars, the created SnO₂ nanoparticles exhibit a much faster response time and sensitivity than other samples, showing the fastest recovery time (18 s) with the highest sensitivity of 6-100 ppm of the HCHO gas. The sensing mechanism of the sensors is investigated by Brunauer-Emmett-Teller (BET) methods and X-ray photoelectron spectroscopy (XPS) analysis, revealing that the pore size distribution and amount of O_V and O_C improve the charge transfer and HCHO adsorption of nanoparticle sensors. Such an effect of morphology control on sensing performance paves an idea for the development of different structure-based HCHO sensors.