Europium ion post-functionalized zirconium metal-organic frameworks as luminescent probes for effectively sensing hydrazine hydrate.

We describe a highly sensitive chemical sensor for the detection of the hydrazine hydrate. The chemical sensor was synthesized by simply doping a UiO-66 type metal-organic framework (MOF) with Eu through a well-known post-synthetic modification method. The Eu@MOF was characterized by powder X-ray diffraction (PXRD), nitrogen gas adsorption isotherm measurements, FTIR, and ICP-MS. This luminescent probe exhibits strong emission intensity, and more significantly, displays various merits, such as high selectivity with notable photoluminescence quenching effect, rapid response time, and remarkable sensitivity with low detection of limit for hydrazine recognition. Under the optimal experimental conditions, hydrazine hydrate can be detected by this method in concentrations as low as 0.18 μM, which is much lower than the threshold limit value (10 ppb, ≈0.3 μM) of hydrazine exposure recommended by the U.S. Environmental Protection Agency (EPA). More interestingly, a portable film sensing device derived from this MOF display quick response to hydrazine hydrate within 90 s. A possible luminescent quenching mechanism for hydrazine hydrate was also investigated.