Inspired by the similarity between the pleated structure of rose petals and the pleated structure of a dog's maxillary turbinate, porous biomass carbon materials with a pleated structure have been successfully prepared from rose petals by direct carbonization. Detailed SEM and TEM characterization showed that the carbonized rose tea (CRT) at 600 °C exhibited a mimetic structure very similar to the dog's maxillary turbinate. The trace K element was detected in the prepared CRT materials, which effectively improved the adsorption capacity of the CRT materials for NH₃ as revealed by density functional theory based on first-principles calculations. As a result, the CRT sensor showed an ultra-high response (60.16k%) to 500 ppm NH₃ with a theoretical detection limit of only 4.82 ppb, in addition to showing a fast recovery (2.0 s), excellent repeatability and long-term stability. Moreover, the formation of nanopores in the pleated structure of the CRT and the sensing mechanism of NH₃ were analyzed. Through a simple, inexpensive and efficient method, this study provides a new strategy for the preparation of a high-performance gas sensor with a bionic structure by directly using the similarity between the biomass structure and dog nose structure.

Triacetone triperoxide (TATP) is a self-made explosive synthesized from the commonly used chemical acetone (C₃H₆O) and hydrogen peroxide (H₂O₂). As C₃H₆O and H₂O₂ are the precursors of TATP, their detection is very important due to the high risk of the presence of TATP. In order to detect the precursors of TATP effectively, hierarchical molybdenum disulfide/reduced graphene oxide (MoS₂/RGO) composites were synthesized by a hydrothermal method, using two-dimensional reduced graphene oxide (RGO) as template. The effects of the ratio of RGO to raw materials for the synthesis of MoS₂ on the morphology, structure, and gas sensing properties of the MoS₂/RGO composites were studied. It was found that after optimization, the response to 50 ppm of H₂O₂ vapor was increased from 29.0% to 373.1%, achieving an increase of about 12 times. Meanwhile, all three sensors based on MoS₂/RGO composites exhibited excellent anti-interference performance to ozone with strong oxidation. Furthermore, three sensors based on MoS₂/RGO composites were fabricated into a simple sensor array, realizing discriminative detection of three target analytes in 14.5 s at room temperature. This work shows that the synergistic effect between two-dimensional RGO and MoS₂ provides new possibilities for the development of high performance sensors.

Covalent organic frameworks (COFs) are an emerging type of porous crystalline polymers formed by combining strong covalent bonds with organic building blocks. Due to their large surface area, high intrinsic pore space, good crystallization properties, high stability, and designability of the resultant units, COFs are widely studied and used in the fields of gas adsorption, drug transport, energy storage, photoelectric catalysis, electrochemistry, and sensors. In recent years, the rapid development of the Internet of Things and people’s yearning for a better life have put forward higher and more requirements for sensors, which are the core components of the Internet of Things. Therefore, this paper reviews the recent progress of COFs in synthesis methods and sensing applications, especially in the last five years. This paper first introduces structure, properties, and synthesis methods of COFs and discusses advantages and disadvantages of different synthesis methods. Then, the research progress of COFs in different sensing fields, such as metal ion sensors, gas sensors, biomedical sensors, humidity sensors, and pH sensors, is introduced systematically. Conclusions and prospects are also presented in order to provide a reference for researchers concerned with COFs and sensors.