Sensors of volatile organic compounds (VOCs) are of great importance for environmental monitoring. Nevertheless, it is a great challenge to develop highly sensitive and selective sensors. In this sense, we report the synthesis of ZnO twin-rods via a combination of the ultrasonic spray nozzle and microwave-assisted hydrothermal methods, which were then loaded with platinum (Pt) nanoparticles (NPs) to obtain Pt/ZnO heterostructures. The VOC detection tests revealed that the 2% Pt/ZnO heterostructure was the best composition, which showed an improved response of 35.2 to 100 ppm of butanone at 450 °C, with high sensitivity to detect low concentrations of butanone (5 ppm) as well as high selectivity and stability. X-ray absorption spectroscopy studies revealed the presence of oxidized Pt species (PtOx) under optimal operating conditions. Thus, the enhanced sensitivity of 2% Pt/ZnO can be attributed to the p–n junction at the PtOx/ZnO interface.
