UV-enhanced NO₂gas sensors based on In₂O₃/ZnO composite material modified by polypeptides

This present study reported a high-performance gas sensor, based on In₂O₃/ZnO composite material modified by polypeptides, with a high sensibility to NO₂, where the In₂O₃/ZnO composite was prepared by a one-step hydrothermal method. A series of results through material characterization technologies showed the addition of polypeptides can effectively change the morphology and size of In₂O₃/ZnO crystals, and effectively improve the sensing performance of the gas sensors. Due to the single shape and small size, In₂O₃/ZnO composite modified by polypeptides increased the active sites on the surface. At the same time, the gas sensing properties of four different ratios of polypeptide-modified In₂O₃/ZnO gas sensors were tested. It was found that the In₂O₃/ZnO-10 material showed the highest response, excellent selectivity, and good stability at room temperature under UV light. In addition, the response of the In₂O₃/ZnO-10 gas sensor showed a strong linear relationship with the NO₂gas concentration. When the NO₂gas concentration was 20 ppm, the response time was as quick as 19 s, and the recovery time was 57 s. Finally, based on the obtained experimental characterization results and energy band structure analysis, a possible gas sensing mechanism is proposed.