Achieving rapid response and high sensitivity in ethanol gas sensing using a Pt/W18O49 ohmic contact via modulating the adsorption and activation properties: Theoretical and experimental insights

In this work, Pt nanoparticles-decorated urchin-like W18O49 microspheres are synthesized by a simple hydrothermal-photodeposition method, and the effect of a contact created between Pt nanoparticles and W18O49 nanorods on response, sensitivity, detection limit, and recovery time in ethanol gas sensing is explored. Transmission electron microscopy (TEM) results confirm the successful deposition of Pt nanoparticles with a size of 5-10 nm on the W18O49 nanorods. The deposition of Pt nanoparticles on the surface of W18O49 nanorods significantly enhances a gas-sensing performance for 10 ppm ethanol at 300 degrees C (with a response value of 22). Compared to the W18O49 sensor, the Pt/W18O49 sensor exhibits faster response-recovery time, lower detection limit, higher response value, and excellent selectivity for detection of ethanol gas. Furthermore, the Pt/W18O49 sensor also shows a fast response-recovery time of 28.5 s and 14.3 s toward 200 ppb ethanol. The results from gas chromatography demonstrate a significant difference between Pt/W18O49 and W18O49 sensors in the efficiency of ethanol conversion to CO2. The interface electron-transfer mechanism between the Pt and W18O49 is further studied by density functional theory (DFT) calculations, providing theoretical insights into the adsorption energy and activation ability of Pt/W18O49 and W18O49 for oxygen and ethanol molecules. The DFT results reveal that an Ohmic contact is formed at the Pt/W18O49 interfaces, indicating the enhanced ability of electron transfer and increased activation of gas molecules. Moreover, the influence of the Ohmic contact on the enhancement of the ethanol gas sensing performance is discussed via electron depletion theory. This study demonstrates a superior performance of Pt-modified W18O49 in ethanol gas detection with theoretical and experimental insights into the mechanism for enhanced ethanol gas sensing