Low-temperature CO2 sensing performance of Pt-decorated ZnO and NiO thin films: synthesis and characterization

This work presents the synthesis of ZnO single-layer films and ZnO/NiO multilayer heterostructures decorated with Pt nanoparticles using aerosol-assisted chemical vapor deposition (AACVD). The method provided a scalable, efficient, and versatile route to fabricate crystalline coatings with tunable composition, controlled morphology, and optical properties at moderate processing temperatures. Structural and morphological analyses confirmed high crystallinity and defect control, directly influencing gas adsorption and sensing behavior. Gas sensing experiments using 10,000 ppm CO₂ demonstrated notable performance: ZnO films exhibited high sensitivity at 100 °C, while ZnO/NiO/Pt heterostructures achieved optimal operation at 200 °C. Under UV-A illumination, ZnO/Pt films displayed enhanced sensitivity, reaching 9.4 ± 0.6 % at 100 °C, with significantly reduced response (8.1 ± 1.3 min) and recovery times (9.4 ± 1.3 min). These findings reveal the synergistic effects of heterostructuring, Pt nanoparticle functionalization, and photoactivation, positioning AACVD-grown oxide films as a competitive platform for energy-efficient and scalable CO₂ sensing applications.