HFIP‐Functionalized Co₃O₄ Micro‐Nano‐Octahedra/rGO as a Double‐Layer Sensing Material for Chemical Warfare Agents

Abstract

Semiconductor metal oxides (SMO)‐based gas‐sensing materials suffer from insufficient detection of a specific target gas. Reliable selectivity, high sensitivity, and rapid response–recovery times under various working conditions are the main requirements for optimal gas sensors. Chemical warfare agents (CWA) such as sarin are fatal inhibitors of acetylcholinesterase in the nerve system. So, sensing materials with high sensitivity and selectivity toward CWA are urgently needed. Herein, micro‐nano octahedral Co3O4 functionalized with hexafluoroisopropanol (HFIP) were deposited on a layer of reduced graphene oxide (rGO) as a double‐layer sensing materials. The Co3O4 micro‐nano octahedra were synthesized by direct growth from electrospun fiber templates calcined in ambient air. The double‐layer rGO/Co3O4‐HFIP sensing materials presented high selectivity toward DMMP (sarin agent simulant, dimethyl methyl phosphonate) versus rGO/Co3O4 and Co3O4 sensors after the exposure to various gases owing to hydrogen bonding between the DMMP molecules and Co3O4‐HFIP. The rGO/Co3O4‐HFIP sensors showed high stability with a response signal around 11.8 toward 0.5 ppm DMMP at 125 °C, and more than 75 % of the initial response was maintained under a saturated humid environment (85 % relative humidity). These results prove that these double‐layer inorganic–organic composite sensing materials are excellent candidates to serve as optimal gas‐sensing materials.

Supramolecular Sensing of Chemical Warfare Agents

“…Wang and co‐workers functionalized micro‐nano octahedral Co 3 O 4 , which was deposited on a layer of reduced graphene (rGO) with hexafluoroisopropanol (HFIP). This system was used to perform the detection of DMMP (Figure 17A) [81] . The sensing material produces a change in the resistance due to absorption of gas molecules through hydrogen bonding, and the starting system can be restored on air, for multi‐cycles sensing (Figure 17B).…”

“…This system was used to perform the detection of DMMP (Figure 17A). [81] The sensing material produces a change in the resistance due to absorption of gas molecules through hydrogen bonding, and the starting system can be restored on air, for multi-cycles sensing (Figure 17B). Selectivity towards other common solvents has been evaluated, with a limit of detection of 0.5 ppm.…”

Room temperature DMMP gas sensing based on cobalt phthalocyanine derivative/graphene quantum dot hybrid materials

“…1 There are some kinds of CWAs that have been used in wars and terrorist attacks. [2][3][4] Sarin gas is one of the most deadly and well-known CWAs, having been used in an attack on the Tokyo subway in 1995 that killed 13 people and poisoned thousands of people. Therefore, timely detection of CAWs such as sarin is a very important issue in the public safety and military elds.…”

“…Dimethyl methylphosphonate (DMMP) is an ideal simulant gas for sarin in the experiments owing to its nontoxicity, the similarity in molecular structure (molecular formula of DMMP is C 4 H 10 FO 2 P, and sarin is C 3 H 9 O 3 P) and functional groups (P] O, P-CH 3 and P-OCH 3 ). 3,4 Several types of materials have been reported for DMMP detection, including carbon nanomaterials, polymers, metal oxides, and their complexes. [6][7][8][9][10][11][12] However, there are always some issues that have not been completely solved such as low response, high operation temperature, and long recovery time.…”

Design of SnO2/ZnO@ZIF‐8 Hydrophobic Nanofibers for Improved H2S Gas Sensing

“…Metal oxide semiconductor (MOS) gas sensors, such as SnO 2 , [1] ZnO, [2] NiO [3] and In 2 O 3 [4] are widely used due to their low cost, portability and fast-dynamic process. [5] However, the shortcomings such as poor selectivity [6] and response susceptible to humidity [7] need to be addressed in practical applications. In order to improve the performance of gas sensors, various routes such as doping, [4,8] noble metal modification, [9] construction of heterojunctions, [3] morphological and structural modulation [10] have been taken.…”