Nickel oxide-based multiwalled carbon nanotube with polyaniline for the detection of chemical warfare agent simulant at ppb level

초록

Chemical Warfare Agents (CWAs) are exceptionally lethal weapons designed for mass destruction, primarily deployed in warfare or conflicts between nations. Although the Organization for the Prohibition of Chemical Weapons (OPCW) has imposed a ban on the use of CWAs, they remain a significant threat due to potential misuse in acts of terrorism or deliberate attacks. Early detection of CWAs is essential for preventing harm and saving lives. With their high toxicity, Dimethyl methyl phosphonate (DMMP) serves effectively as a simulant for the nerve agent sarin. In this study, in-house fabricated surface acoustic wave (SAW) sensors operating at 250 MHz were employed. We synthesized nitrogen-doped multiwalled carbon nanotubes (N-MWCNT), nickel oxide (NiO), N-MWCNT@NiO, and N-MWCNT@NiO/polyaniline (PANI), which were subsequently drop-coated onto the sensing layer in SAW sensors to investigate the operating mechanisms underlying DMMP detection. The synthesized materials were characterized using FTIR, XRD, XPS, SEM, TEM, and BET surface area analysis. The frequency responses of the composite nanomaterials were analyzed and compared under controlled conditions, yielding valuable insights into their detection capabilities. The SEM results for N-MWCNT@NiO/PANI indicate that nickel oxide is attached to the noodle-shaped carbon nanotubes, with clusters of PANI also present. EDS mapping confirms the successful integration of nickel oxide within the composites. The TEM results reveal that nickel oxide has an amorphous and dark structure, while the nanotubes maintain a tubular shape, accompanied by clusters of PANI. The N-MWCNT@NiO/PANI exhibits clear reversible responses to DMMP starting at a concentration of 150 ppb. Reproducibility tests demonstrate consistent responses for 200 ppb DMMP across all synthesized materials. The BET test of N-MWCNT@NiO/PANI indicates an increase in pore size, with measurements of 110 Å for adsorption which may have contributed to the effective detection of DMMP. © 2026 SPIE.

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