Non-contact real-time detection of trace nitro-explosives by MOF composites visible-light chemiresistor

To create an artificial structure to remarkably surpass the sensitivity, selectivity and speed of the olfaction system of animals is still a daunting challenge. Herein, we propose a core-sheath pillar (CSP) architecture with a perfect synergistic interface that effectively integrates the advantages of metal-organic frameworks and metal oxides to tackle the above-mentioned challenge. The sheath material, NH2-MIL-125, can concentrate target analyte, nitro-explosives, by 1012 times from its vapour. The perfect band-matched synergistic interface enables the TiO2 core to effectively harvest and utilize visible light. At room temperature and under visible light, CSP (TiO2, NH2-MIL-125) shows an unexpected self-promoting analyte-sensing behaviour. Its experimentally reached limit of detection (∼0.8 ppq, hexogeon) is 103 times lower than the lowest one achieved by a sniffer dog or all sensing techniques without analyte pre-concentration. Moreover, the sensor exhibits excellent selectivity against commonly existing interferences, with a short response time of 0.14 min.