Recently, a team of material scientists led by Chao Zhang from Yangzhou University, China, presented a universal design principle of oxygen vacancy-engineered interfacial redox kinetics, providing new mechanistic insights into moderate electronic structure and improved charge transfer kinetics at the gas-solid interface. The findings were published in the Journal of Advanced Ceramics on May 27th, 2025.
Room-temperature gas sensor based on oxygen vacancy manipulated 1D MoO3 for TMA biomarker detection: New mechanistic insights into moderate electronic structure, optimized charge transfer kinetics and balanced adsorption/desorption, sensing performance, and application. Image Credit: Journal of Advanced Ceramics, Tsinghua University Press
Accurately detecting dangerous gases using low-cost gas sensors is critical in public health, environmental protection, and industrial safety. Metal oxide-based (MOXs) chemiresistive gas sensors are becoming more important in environmental monitoring, food safety detection, and healthcare diagnostics due to their ease of integration and low cost.
MOXs frequently require high temperatures (100-500 ℃) to overcome the energy barriers of redox reactions, resulting in significant power consumption, poor safety, and operational stability. The high working temperature necessitates a heater unit, which increases the fabrication process's cost and complexity. As a result, gas sensors that operate at room temperature have received a lot of interest.
The RT response of MOXs to H2S, NO2, and NH3 may be realized by connecting carbon-based nanomaterials, creating hetero-structures, decorating with catalysts (metal elements, metal oxides, etc.), and designing distinctive morphology. However, it is still challenging to uncover the gas sensing mechanism and use MOXs without catalysts to quickly detect volatile organic compounds at room temperature with high sensitivity and selectivity.
Using oxygen vacancy engineering, MOXs' electronic structure and surface activity have improved their performance in gas sensing, energy storage, and hetero-catalysis applications. Notably, oxygen vacancies can operate as active sites for molecule adsorption and provide free electrons, which affects the ability to collect electrons and lower reaction barriers—two critical functions in improving the effectiveness of sensing materials.
Therefore, controlling MOXs’ electronic properties and surface activity is essential to achieving RT-sensing capabilities. Indeed, regulating the metal oxide’s oxygen vacancy is a potential strategy for creating high-performance RT gas sensors; nevertheless, it is also critical to provide information about the enhanced LOD and response and recovery speed made possible by oxygen vacancies.
This research will use portable equipment to improve the activity-function connection of metal oxide catalysts and enable ultrasensitive and quick VOC detection at any time and location.
In this work, to overcome the sluggish kinetics and imbalanced adsorption/desorption of MoO3, the synergetic strengthen strategy of oxygen vacancy and 1D nanostructure for enabling room temperature biomarker detection was developed.
Chao Zhang, Professor and Leader, Jiangsu Key Laboratory of Surface Strengthening and Functional Manufacturing, Yangzhou University
At 22 ℃, rich oxygen vacancy-MoO3-x (MoO3-x-R) showed markedly improved TMA sensing characteristics, such as rapid response (0 → 7.6 @ 20 ppm), quick response/recovery speed (60/90 s), superior selectivity, low LOD (400 ppb), and long-lasting stability surpassing 28 days.
“To gain the universal enhanced mechanisms, the improved electronic structure, surface redox, and charge transfer kinetics by oxygen vacancy engineering were elucidated through experimental, DFT, and MD studies. Their comprehensive studies revealed that the rich oxygen vacancy enables accelerated charge transfer, superior redox capacity, and improved adsorption/desorption kinetics, thus significantly improving the sensitivity, LOD, and response/recovery speed,” Zhang added.
The study team is hopeful that their findings may be of use in the future. It was also shown that the portable sensor gadget was feasible for detecting food safety.
Zhang stated, “The on-field detection tests manifested that the device was capable of quantitively TMA monitoring and rapid & non-destructive fish freshness detection. This work will contribute to developing high-performance VOC sensors.”
The research team will concentrate on in-situ investigation of the activity-functions connection of metal oxide, enhanced sensing performance, and machine learning-driven smart gas sensors in the future to obtain a better understanding of the concept and a wider range of applications for MOS-based gas sensors.
The Natural Science Youth Foundation of Jiangsu Province, China, under Grant No. BK20240933, and the National Natural Science Foundation of China, under Grant No. 52402202, funded this study.
Journal Reference:
Wu, K., et al. (2025) Oxygen vacancy-rich engineering optimized molybdenum trioxide microbelts for room-temperature ppb-level trimethylamine detection. Journal of Advanced Ceramics. doi.org/10.26599/jac.2025.9221102.