Ionic liquid-assisted synthesis of In₂O₃ nanoparticles for ultra-fast detection of unsymmetrical dimethylhydrazine

Due to the unique physiochemical properties of ionic liquids, they are extensively used as agent or solvent in the synthesis process of nanomaterials. The tailored growth process of functional nanomaterials might result in performance modification for them. In this work, In₂O₃ nanoparticles were prepared via the hydrothermal method and subsequent calcination (400 °C, 500 °C, 600 °C and 700 °C). An ionic liquid (1-hexadecyl-3-methylimidazolium chloride, [C₁₆Mim] Cl) was introduced in the hydrothermal process. After calcination, trace of [C₁₆Mim] Cl inclusion in In₂O₃ was pyrolyzed with Cl residue (Cl-In₂O₃). In compare with control sample synthesized without [C₁₆Mim] Cl (pure In₂O₃), In₂O₃-600 (Cl-In₂O₃ calcined at 600 °C) exhibited an excellent UDMH sensing performance at 225 °C. The fabricated sensor achieved a high response value (71.0 ± 2.1 to 100 ppm), rapid response time (2 s), good selectivity and a low theoretical limit of detection (1.72 ppb) to UDMH gas. Various characterizations, in regard to oxygen vacancy, surface texture structure, energy band structure and surface acidity, were utilized to analyze the cause for enhanced performance. The ionic liquid inclusion increases the contents of adsorbed oxygen species and improves the adsorption capacity to UDMH gas. This work indicates that the synthesized In₂O₃ nanoparticles could be the potential candidates for rapid UDMH detection in some specific application scenarios.