Enhancing Gas Sensing Properties in WOx-CeOy Heterostructures through Surface and Interface Engineering

• Applicant: Professor Dr. Jan Ingo Flege
• Subject Area: Synthesis and Properties of Functional Materials
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 544815996

The project aims to develop a description of the mechanisms that determine the properties of sensors, especially in the context of hybrid structures. Particularly, the scientific goal of the project will be demonstrated through the utilization of the WOx-CeOy bilayer sensing system. The main focus is placed on elucidating the role of the interface between two sensing materials and understanding how the response mechanism is intricately linked to its properties. This involves in-depth in-situ and operando studies, a crucial and original component of the proposed research. An additional key aspect of our scientific goal involves investigating the influence of diversifying the sensor's active area on the gas detection process. This exploration is pivotal for understanding and potentially manipulating the diffusion process of gas molecules reacting with the sensor material. The project hypothesizes that insights into the role and properties of the interface in hybrid structures will enable precise adjustments of gas sensor response and selectivity for desired gases, surpassing the capabilities offered by individual metal oxide materials. Here, hybrid layered structures emerge as a unique group of materials with the potential to significantly improve gas sensor performance. Additionally, the use of two different yet compatible microelectronic technologies for oxide layer deposition (magnetron sputtering and atomic layer deposition) will be demonstrated. A key aspect of our approach is the novel use of the atomic layer deposition method accompanied by operando growth control via spectroscopic ellipsometry, optical reflectance microscopy, and mass spectrometry for synthesizing ultrathin CeOy layers. This unique combination provides thorough coverage of the WOx layer and forming an n-n-type WOx-CeOy heterostructure for sensing applications. The use of advanced in-situ spectroscopic techniques will allow to address the intricate interaction of selected gases (hydrogen, ammonia, acetone, carbon dioxide) with the surface of the fabricated samples, providing a comprehensive understanding of the sensing mechanism. Preliminary studies conducted by the collaborative team of project applicants (BTU and WUST) have demonstrated the excellent sensing response of CeOy, achieving a change in resistance by several orders of magnitude even at an operating temperature as low as 150 °C, particularly to reducing gases like hydrogen, an important energy vector in a future society based on renewables. Astonishingly, such hybrid sensors have not been thoroughly investigated in terms of their sensing performance to date.

• DFG Programme: Research Grants
• International Connection: Poland
• Cooperation Partner: Professor Dr.-Ing. Jaroslaw Krzysztof Domaradzki