Enhancing Methane Gas Sensing through Defect Engineering in Ag–Ru Co-doped ZnO Nanorods

Li, Xun, Hu, Hui, Tan, Tian, Sun, Mengjing, Bao, Yuwen, Huang, Zhongbing ORCID: https://orcid.org/0000-0003-2549-7917, Sohail, Muhammad, Xia, Xiaohong ORCID: https://orcid.org/0000-0002-1332-9310 and Gao, Yun ORCID: https://orcid.org/0000-0002-9898-5690 (2024) Enhancing Methane Gas Sensing through Defect Engineering in Ag–Ru Co-doped ZnO Nanorods. ACS Applied Materials and Interfaces, 16 (20). pp. 26395-26405. ISSN 1944-8244

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Abstract

Detection of leaks of flammable methane (CH4) gas in a timely manner can mitigate health, safety, and environmental risks. Zinc oxide (ZnO), a polar semiconductor with controllable surface defects, is a promising material for gas sensing. In this study, Ag–Ru co-doped into self-assembled ZnO nanorod arrays (ZnO NRs) was prepared by a one-step hydrothermal method. The Ag–Ru co-doped sample shows a good hydrophobic property as a result of its particular microstructure, which results in high humidity resistance. In addition, oxygen vacancy density significantly increased after Ag–Ru co-doping. Density functional theory (DFT) calculations revealed an exceptionally high charge density accumulated at the Ru sites and the formation of a localized strong electric field, which provides additional energy for the CH4 reaction with •O2– at the surface at room temperature. Optimized AgRu0.025–ZnO demonstrated an outstanding CH4 sensing performance, with a limit of detection (LOD) as low as 2.24 ppm under free-heat and free-light conditions. These findings suggest that introducing defects into the ZnO lattice, such as oxygen vacancies and localized ions, offers a promising approach to improving the gas sensing performance.