Vicentini Nayton C, Lima Alessandro H, Carvalho Giovanni R, Tavares Camila T, Fernandes Anne C P, Cunha Clemilda C S, Araújo Joyce R, Palheta Sanair M S, Fragneaud Benjamin, Maciel Indhira O, Legnani Cristiano, Quirino Welber G
Nanoscience and Nanotechnology Group - Nano, Physics Department, UFJF, Juiz de Fora-MG 36036-900, Brazil.
Materials Metrology Division, National Institute of Metrology, Quality and Technology - INMETRO, Duque de Caxias-RJ 25250-020, Brazil.
ACS Omega. 2025 Jul 18;10(29):32257-32268. doi: 10.1021/acsomega.5c04175. eCollection 2025 Jul 29.
Graphene oxide (GO), a structurally defective 2D carbon nanomaterial, is very promising for relative humidity (RH) sensing applications due to the presence of diverse oxygenated functional groups (OFGs) in its structure. The characteristics of GO, such as flake size, degree of oxidation and exfoliation, permanent structural defects, and chemical composition, directly impact the RH detection performance of GO. In this work, we investigated the performance of resistive RH sensors based on three types of GO, prepared using modifications of the Hummers' method, namely, GO-I, GO-II, and GO-III, having different chemical composition, degree of oxidation, as well as different levels of permanent structural defects (carbon vacancies) at the basal plane. GO-based RH sensors were fabricated by drop-casting GO suspensions onto aluminum interdigitated electrodes thermally evaporated onto glass substrates. Among the three characterized RH sensors, GO-II-based devices showed superior performance, with a sensitivity of 2113 ± 2% compared to 1592 ± 1% for GO-I and 388.1 ± 0.1% for GO-III, respectively. All GO sensors demonstrated rapid response and recovery times (ca. 2 and 3 s). Our results indicate that improved quantities of highly polar OFGs, such as carbonyl and hydroxyl groups, and the associated permanent structural defects in GO-II, significantly improved its RH sensing properties. In addition, all GO-based RH sensors can be operated at only 0.1 V, making them suitable for integration into low-power systems.
氧化石墨烯（GO）是一种结构有缺陷的二维碳纳米材料，由于其结构中存在多种含氧官能团（OFGs），在相对湿度（RH）传感应用方面极具前景。GO的特性，如薄片尺寸、氧化程度和剥落程度、永久性结构缺陷以及化学成分，直接影响GO的RH检测性能。在这项工作中，我们研究了基于三种GO的电阻式RH传感器的性能，这三种GO采用改进的Hummers法制备，即GO-I、GO-II和GO-III，它们具有不同的化学成分、氧化程度以及基面不同水平的永久性结构缺陷（碳空位）。基于GO的RH传感器是通过将GO悬浮液滴铸到热蒸发在玻璃基板上的铝叉指电极上制备的。在三种表征的RH传感器中，基于GO-II的器件表现出优异的性能，灵敏度为2113±2%，而基于GO-I的器件灵敏度为1592±1%，基于GO-III的器件灵敏度为388.1±0.1%。所有GO传感器都表现出快速的响应和恢复时间（约2秒和3秒）。我们的结果表明，GO-II中大量高极性OFG（如羰基和羟基）以及相关的永久性结构缺陷显著改善了其RH传感性能。此外，所有基于GO的RH传感器仅需0.1 V即可运行，使其适合集成到低功耗系统中。
