UV-enhanced NO 2 gas sensors based on In 2 O 3 /ZnO composite material modified by polypeptides.

This present study reported a high-performance gas sensor, based on In 2 O 3 /ZnO composite material modified by polypeptides, with a high sensibility to NO 2 , where the In 2 O 3 /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 In 2 O 3 /ZnO crystals, and effectively improve the sensing performance of the gas sensors. Due to the single shape and small size, In 2 O 3 /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 In 2 O 3 /ZnO gas sensors were tested. It was found that the In 2 O 3 /ZnO-10 material showed the highest response, excellent selectivity, and good stability at room temperature under UV light. In addition, the response of the In 2 O 3 /ZnO-10 gas sensor showed a strong linear relationship with the NO 2 gas concentration. When the NO 2 gas 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.