CuO-decorated bismuth subcarbonate p-n heterostructured micro-flowers for high-selectivity VOC gas sensor arrays and cooked rice quality assessment

Aroma is one of the earliest cues people use to judge food quality, and in cooked rice it is strongly shaped by volatile organic compounds (VOCs) that evolve during storage. However, reliably tracking these VOCs in real time is difficult because many relevant molecules have low volatility and appear in complex mixtures, while conventional lab methods (such as GC-MS workflows) can be costly and time-consuming for routine monitoring.

In a new study, a research team led by Prof. Chao Zhang developed a room-temperature gas-sensing platform designed to recognize VOC patterns associated with cooked rice quality. The core sensing material is a CuO-decorated bismuth subcarbonate (Bi₂O₂CO₃) micro-flower architecture that forms a p-n heterojunction. The team reports that this interface engineering increases defect-related active sites (oxygen vacancies), improves charge transport, and strengthens the sensor’s ability to differentiate target VOCs.

Rather than relying on a single sensor, the researchers assembled a four-channel array using a series of Cux-BC sensing layers (x = 10, 20, 30, 40) and integrated it with electronics that convert voltage signals to resistance for stable multi-channel acquisition. In tests at room temperature (about 25^oC), each channel responded to the target VOCs, and the overall array demonstrated clear discrimination among nonanal, benzaldehyde, and 1-octen-3-ol using principal component analysis (PCA).

To connect VOC sensing with food-quality assessment, the team first verified relevant VOC species in cooked rice samples via headspace extraction and GC-MS, then applied the sensor array to cooked rice prepared from grains stored for different time windows. Using PCA and linear discriminant analysis (LDA) on the array’s dynamic response curves, the system differentiated groups corresponding to earlier and later storage stages (with clearer separation emerging across multi-week storage intervals). This suggests the platform could support practical freshness classification when rice aroma profiles shift during storage.

“By building a CuO/Bi₂O₂CO₃ p-n heterostructure and tuning the CuO loading, the sensor array can read subtle VOC patterns at room temperature, which is important for low-power, portable monitoring,” said Prof. Chao Zhang. The team also used molecular dynamics simulations to examine how target VOC molecules and oxygen interact and diffuse on the material surfaces, helping rationalize why interface design can amplify electrical signals in complex VOC environments.

The team published their work in Journal of Advanced Ceramics on December 20, 2025.

Looking ahead, the researchers note that the same materials-and-array strategy could extend beyond cooked rice to broader agricultural and food scenarios where aldehydes and alcohols serve as quality markers, such as grain storage surveillance, freshness tracking for other foods, and smart packaging or IoT-enabled monitoring, especially when paired with wireless communication and data-driven algorithms.

This work was supported by the Outstanding Youth Foundation of Jiangsu Province of China (BK20211548), the Yangzhou Science and Technology Plan Project (YZ2023246), the Qinglan Project of Yangzhou University, and the China Scholarship Council (202308320445).

About Author

Chao Zhang received a B.S. degree from the Chongqing University (China) in 2003 and a joint Ph.D. degree from Technology University of Belfort-Montbéliard (France) and Xi'an Jiaotong University (China) in June 2008. From September 2007 to January 2009, he worked as a teaching-research assistant in Technology University of Belfort-Montbéliard. Since Feb 2009, he is postdoctoral researcher, and then a senior researcher in Materials Science Department of engineering School of University of Mons (Belgium). In 2014, he joined Yangzhou University China) as professor where he is leading a research group on thermal spray coatings and gas sensors. He is Vice Dean (August 2016 to September 2022) and Dean (September 2022 to present) of College of Mechanical Engineering. His research interests include thermal-sprayed techniques and coatings, especially gas sensing and wear-resistant coatings.

Zichen Zheng received his B.S. degree in 2020 at Hefei University of Technology (China). He is currently pursuing his Ph.D degree at Yangzhou University (China) and University of Mons (Belgium). He takes interests in smart materials for high-performance gas sensors working at room temperature applying for food quality and plant pest detection.

About Journal of Advanced Ceramics

Journal of Advanced Ceramics (JAC) is an international academic journal that presents the state-of-the-art results of theoretical and experimental studies on the processing, structure, and properties of advanced ceramics and ceramic-based composites. JAC is Fully Open Access, monthly published by Tsinghua University Press, and exclusively available via SciOpen. JAC’s 2024 IF is 16.6, ranking in Top 1 (1/33, Q1) among all journals in “Materials Science, Ceramics” category, and its 2024 CiteScore is 25.9 (5/130) in Scopus database. ResearchGate homepage: https://www.researchgate.net/journal/Journal-of-Advanced-Ceramics-2227-8508