Reduced Graphene (rGO) and Semiconductor Metal Oxides (MOS) based nanocomposites for application as toxic gas sensors

The detection of different types of gases is becoming more and more important in our society due to the need to identify toxic gases and organic vapors for environmental and human safety, for emission/control in the industrial sector and for medical diagnosis. Efforts by the scientific community working in this area of ​​research are dedicated to researching new materials capable of detecting gases at room temperature, in standard environmental conditions, and that present high selectivity and sensitivity. Among the materials that have been considered promising and that present these characteristics is obtained through the association of semiconductor metal oxides (MOS) and reduced graphene (rGO). The association of graphene with MOS, compared to MOS-only sensors, has shown better performance in gas detection in many aspects, such as sensitivity, response/recovery times and operating temperature. Although different works on this topic have been published recently, many aspects of research in this area are still open. In this context, the general objective of the research project is the study of sensor properties in relation to different toxic gases of composite materials formed by reduced graphene (rGO) and semiconductor metal oxides (MOS). Determining which are the best conditions (rGO/MOS ratio and MOS morphology) that lead to better sensor properties and the mechanisms involved in the process will be fundamental for the project's success. To achieve these goals, we will obtain samples of reduced graphene (rGO) from graphene oxide using a laser radiation source; to obtain nanostructured samples in powder form of the semiconductor metallic oxides ZnO, In2O3-SnO2 (ITO), WO3 and CuO through the polymeric precursor method; obtain nanostructured MOS samples with different morphologies using nanocellose as a template and finally, perform the synthesis of MOS/rGO nanocomposites whose sensor properties will be characterized. As innovative aspects of the project, the use of laser radiation in the graphene reduction process and the use of nanocellulose as a template to obtain metallic oxides with different morphologies can be highlighted. The samples obtained will be characterized using conventional and advanced techniques. Finally, the sensing properties of the pre-selected samples that present an adequate resistance value will be evaluated with different toxic gases (CO, CO2, Acetone, Ethanol, NO and O3). With this project, we hope to contribute to the scientific and technological development of this important research area through new strategies for the synthesis of nanostructured materials, producing sensors that act at room temperature and present a better degree of selectivity.鉴于环境与人类安全领域需识别有毒气体及有机蒸气、工业领域需开展排放管控，以及医疗诊断的实际需求，各类气体检测在当今社会的重要性与日俱增。该研究领域的科研团队始终致力于研发可在标准环境条件下的室温环境中实现气体检测，且具备高选择性与高灵敏度的新型检测材料。其中，半导体金属氧化物（semiconductor metal oxides, MOS）与还原石墨烯（reduced graphene, rGO）的复合体系被视为具备上述优良特性的极具潜力的材料之一。相较于单一MOS传感器，石墨烯与MOS的复合体系在气体检测的多项性能指标上展现出更优表现，包括灵敏度、响应/恢复时长以及工作温度。尽管近期已有诸多围绕该主题的研究成果发表，但该领域仍有诸多研究方向有待进一步探索。在此背景下，本研究项目的总体目标为探究由还原石墨烯（rGO）与半导体金属氧化物（MOS）构成的复合材料针对不同有毒气体的传感性能；明确可实现最优传感性能的最佳制备条件（rGO与MOS的配比以及MOS的形貌），以及该过程中的相关作用机制，这将是本项目取得成功的核心关键。为达成上述目标，本研究将通过以下步骤开展工作：采用激光辐射法以氧化石墨烯为原料制备还原石墨烯（rGO）；通过聚合物前驱体法制备纳米结构的ZnO、In₂O₃-SnO₂（ITO）、WO₃及CuO半导体金属氧化物粉体样品；利用纳米纤维素作为模板制备具备不同形貌的纳米结构MOS样品；最终合成MOS/rGO纳米复合材料并对其传感性能进行表征。本项目的创新亮点在于：在石墨烯还原过程中引入激光辐射技术，以及以纳米纤维素为模板制备不同形貌的金属氧化物。所制备的全部样品将通过常规及先进表征技术进行系统性分析。最后，我们将针对筛选出的具备合适阻值的样品，采用CO、CO₂、丙酮、乙醇、NO、O₃等多种有毒气体开展传感性能测试。通过本项目，我们期望通过新型纳米结构材料的合成策略，为该重要研究领域的科技发展贡献力量，成功制备出可在室温下工作且具备更高选择性的气体传感器。