Thin film technology offered several possibilities and advancements in modern gas sensor devices. We have developed template-free, Sb-doped nanometer thin-SnO 2 films for CO/NH 3 gas detection using a facile spray technique on the glass substrates. Structural, surface, optical, and resistivity properties of as-deposited films were investigated as a function of film thickness for enhanced gas sensor performance. Structural analysis confirms tetragonal phase formation along with the texture behavior of the films. Increasing film thickness leads to an increase in the texture growth of the film, which can also impact gas sensing. As-deposited films display a polygon microstructure with dense film formation, leading to a large sensing surface. HR-TEM analysis confirms that Sb-doped nanometer-thin SnO 2 (ATO) films have a relatively low crystallite size than pristine TO films. Pristine SnO 2 (TO) film has better bandgap matching with bulk SnO 2 samples. ATO thin films have relatively lower band gap values and decrease as a function of film thickness due to enhanced free carrier density upon Sb doping. To determine the best optimum condition, gas sensing analysis was investigated at different operating temperatures (150, 200, and 250 °C) for different gas concentrations (5 to 25 ppm). Designed TO and ATO film base sensors exhibit rectifying gas-sensing behavior, indicating the formation of a potential barrier across the film surface and metal (Au) interface. ATO film-based gas sensor devices showed enhanced response toward CO/NH 3 gas detection compared to pristine TO thin film. Also, ATO thin films exhibited better stability and selectivity toward CO gas detection than NH 3 gas. However, the ATO film with very low resistance below 1 kΩ is not able to be used as a gas sensor. Hence, the results obtained indicate the optimum resistive behavior of nanometer ATO films' applicability toward enhanced CO/NH 3 gas detection.

Summary Reduced graphene oxide (RGO) based composite non‐selective solar absorber coatings (RGO/silicate) were developed using a simple spray technique. RGO powders were prepared using the modified Hummers' method. RGO‐silicate suspensions were obtained by adding an appropriate quantity of RGO in a sodium silicate solution. Transmission electron microscopy studies showed the corrugated morphology of reduced graphene oxide powders. The presence of RGO in the composite absorber coatings was confirmed by X‐ray photoelectron spectroscopy data. In order to study the thermal stability, the coatings were deposited on stainless steel (SS) and Inconel substrates. The composite nonselective coating exhibited an absorptance (α) of 0.96 and emittance (ε) of 0.88 at 82°C on SS and Inconel substrates. The coatings sprayed on SS substrates showed good thermal stability for 428 hours at 500°C in air. The coatings sprayed on Inconel substrates were thermally stable in air at 600°C for 96 hours. The performance evaluation tests revealed that these coatings can be used for concentrated solar power applications.