Abstract Formaldehyde gas sensor with high performance is indispensable for monitoring indoor air quality. Exploring novel nanostructured composites as gas sensing materials is considered to be a feasible way to enhance the sensing performance. In this work, one-step hydrothermal method was employed for facile synthesis of ZnO/Zn2SnO4 nanocomposites and the as-prepared sample took on a homogeneous hexagonal lamellar nanostructure with a diameter of 600 nm–900 nm and thickness of about 100 nm. Gas sensing properties of the sample were tested and the results demonstrated that the ZnO/Zn2SnO4 composites possessed excellent sensing performances to formaldehyde. At 160 °C, the ZnO/Zn2SnO4 composites based sensor exhibited a high response of 22.5 towards 100 ppm of formaldehyde and a detection limit as low as 500 ppb. Compared with pristine Zn2SnO4 and ZnO, ZnO/Zn2SnO4 composites showed higher sensitivity (increased by 80% and 120%), better selectivity and lower detection limit. The noteworthy improvement of formaldehyde sensing performances could be attributed to the synergetic effect as well as the formation of n-n type heterojunctions between Zn2SnO4 and ZnO. The mechanism involved in gas sensing performance of ZnO/Zn2SnO4 composites was also discussed.

中文翻译：

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基于一步水热合成的 ZnO/Zn2SnO4 复合材料增强甲醛的气敏性能

摘要 高性能的甲醛气体传感器是监测室内空气质量不可或缺的一部分。探索新型纳米结构复合材料作为气敏材料被认为是提高传感性能的可行方法。在这项工作中，采用一步水热法简便地合成了 ZnO/Zn2SnO4 纳米复合材料，所制备的样品具有均匀的六边形层状纳米结构，直径为 600 nm-900 nm，厚度约为 100 nm。测试样品的气敏特性，结果表明ZnO/Zn2SnO4复合材料对甲醛具有优异的传感性能。在 160 °C 时，基于 ZnO/Zn2SnO4 复合材料的传感器对 100 ppm 的甲醛表现出 22.5 的高响应和低至 500 ppb 的检测限。与原始的 Zn2SnO4 和 ZnO 相比，ZnO/Zn2SnO4 复合材料显示出更高的灵敏度（分别提高了 80% 和 120%）、更好的选择性和更低的检测限。甲醛传感性能的显着提高可归因于协同效应以及 Zn2SnO4 和 ZnO 之间 nn 型异质结的形成。还讨论了涉及 ZnO/Zn2SnO4 复合材料气敏性能的机制。