Fe-Ni-MOF-derived NiFe2O4/NiO heterostructure for detection of 2-CEES at ppb level

Rapid, highly sensitive detection of mustard gas is a critical requirement in public safety and national defense. However, achieving highly sensitive, ppb-level detection of mustard gas under low-power conditions remains a significant challenge. Focusing on the typical blister agent simulant 2-chloroethyl ethyl sulfide (2-CEES), a solvothermal method was employed combined with controlled thermal treatment to fabricate an ultrathin porous NiFe 2 O 4 /NiO nanosheets heterostructure sensor derived from an Fe-Ni-MOF in-situ grown on a ceramic tube in this study. This material possesses uniformly distributed intimate heterogeneous interface, a high specific surface area (95.8 m 2 ·g −1 ), and abundant surface active sites, thereby significantly enhancing its adsorption and catalytic oxidation capability toward 2-CEES. At a low operating temperature of 130 °C, the sensor demonstrates a high response of 41.5 toward 10 ppm 2-CEES, a rapid recovery capability of only 84 s, and a low detection limit of 20 ppb, along with excellent selectivity, humidity resistance, reproducibility, and long-term stability. Through systematic characterization including XPS, in-situ DRIFTS, TPD, and DFT calculations, the multi-step catalytic oxidation pathway of 2-CEES on the composite surface is elucidated, along with the mechanism by which the heterostructure enhances gas-sensing performance via band structure modulation, interfacial charge transfer, and the built-in electric field. This study offers both new materials and novel insights for the development of low-power, highly sensitive sensors for trace detection of chemical warfare agents.