Rapid detection of low concentration CO using Pt-loaded ZnO nanosheets

Unloaded and Pt-loaded ZnO nanosheets with 120-170 nm sizes were successfully synthesized by a facile one-pot hydrothermal route followed by a calcination treatment. The as-synthesized samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). It can be clearly observed that Pt nanoparticles with the diameter of 3-5 nm were uniformly loaded on the surface of ZnO nanosheets. A contrastive study based on CO gas sensing performance of bare ZnO and Pt/ZnO was carried out. According to the measurement results, the loading of Pt remarkably upgraded the sensing capability toward CO. The 0.50 at.% Pt/ZnO based gas sensor exhibited an obvious response value of 3.57 toward 50 ppm CO and fast response/recovery time (6/19 s). Besides, the detection limit was as low as 0.10 ppm and the optimal operating temperature was decreased from 210 °C to 180 °C. The enhanced CO sensing performance by Pt nanoparticles could be attributed to the combination of chemical sensitization and electronic sensitization. The 0.50 at.% Pt/ZnO is an efficient sensor material for rapidly detecting low-concentration CO.