Fabrication of Diamond/Metal Oxide Hybrid Structures: Towards Gas Sensors with Enhanced Sensitivity and Selectivity

The release of hazardous compounds such as NOx, SOx, CO, NH₃, other nitrogen or sulfur-containing compounds, and volatile organic compounds (benzene, toluene, methanol, etc.) in the atmosphere is of significant concern for human health. Therefore, there is a rising demand for advanced chemiresistor sensors, which need to satisfy the following requirements: high sensitivity, selectivity, stability and reproducibility. In recent years, various metal oxides (e.g., ZnO, SnO₂, CeO₂) have been recognized as promising materials for the detection/sensing of toxic pollutants and hazardous gases. Yet, chemiresistor sensors based on metal oxides have exhibited rather poor selectivity (i.e., simultaneous sensitivity to reducing and oxidizing gases) along with the necessity of high temperature (&gt; 300 °C) operation.<br/>In this work we demonstrate fabrication of hybrid structures based on diamond (intrinsic and boron-doped) and metal oxides (MOx) for their application as active components in gas chemiresistor sensors. We investigate the effect of doping and the diamond structure (planar and/or 3D geometries) on the sensing characteristics of hybrid structures (e.g., sensitivity and selectivity) towards various gases. Fabricated diamond/MOx structures were characterized via various microscopic and spectroscopic techniques, and the effect of their electrical characteristics on the sensing properties is discussed.<br/>This work was supported by the Czech Science Foundation grant GACR 22-04533S.