Bilayer oxides chemiresistor design for highly selective detection of dimethyl methylphosphonate

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.