The graphene-based room-temperature chemiresistive gas sensors have low sensitivity (especially for ppb-level organophosphorous compounds, OPCs), limiting their practical applications. Herein, a novel coupling single-atom Cu and N-enriched, π-conjugated carbon nanodots (NCDs) strategy is proposed to synthesize graphene-based sensing materials with excellent room-temperature DMMP sensing performances. Taking rGO-NCDs-Cu as the example, the N-enriched structures facilitate the adsorption of DMMP by providing more active sites and strengthening the hydrogen bonding interactions between -NH 2 and DMMP molecules. The π-conjugated structures can construct large π-delocalization network promoting charge generation and transport. The N-enriched and π-conjugated structures also result in narrowing band gap of NCDs, effectively enabling the increase of carrier transfer rate. Moreover, the introduction of single-atom Cu sites with Cu-N 2 Cl 2 structure further strengthens the hydrogen bonding interactions between sensing materials and DMMP molecules. Benefiting from this novel coupling strategy, rGO-NCDs-Cu sensor shows high response value of 13.95 % towards 340 ppb DMMP at room temperature. Meanwhile, rGO-NCDs-Cu sensor exhibits short response time (77 s) and recovery time (198 s), low practical limit of detection (34 ppb), excellent repeatability and high selectivity. Our work offers a new strategy for rational design of graphene-based materials for detection of OPCs at room temperature.
Boyi Wang,Junchao Yang,Deran Qu,Liupeng Zhao,Tianshuang Wang,Qibin Huang,Peng Sun,Geyu Lu
Oxide chemiresistors have gained considerable attention for detecting warfare nerve agents such as sarin gas over the years, yet have failed to materialize due to poor selectivity. To address this challenge, we presented the design of a bilayer DMMP chemiresistor, where using Au nanoparticles (NPs)-loaded ZnFe 2 O 4 as sensing layer, and zeolite as filtering layer, for detecting dimethyl methylphosphonate (DMMP)—as stimulant nerve agent sarin. Compared with monolayer Au-ZnFe 2 O 4 chemiresistor showing acetone sensing properties, the bilayer sensor could detect trace-level (50 ppb) DMMP exclusively with high selectivity, repeatability, and stability, which was attributed to the pre-decomposing of interfering gases on zeolite overlayer as confirmed by the mass spectrometer. Additionally, the highly active Au NPs, that promoted the adsorption and activation of oxygen, facilitates DMMP sensing reaction occurs on the surface of Au-ZnFe 2 O 4 sensing layer, which was further researched on quasi-in-situ Fourier transform infrared spectroscopy (FTIR). This work opened up a way for sarin gas detection using bilayer oxides chemiresistors.
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