The space-charge region at CsPbBr3 NC⊆Pb-MOF p-n junction by self-sacrificing MOFs to selective detect NH3·H2O or Fe3+

The rational design of p-n heterojunction is highly desirable to optimize electron distribution and photocarriers' transfer pathway at space-charge region, which would influence the fluorescence detection. Herein, the inorganic perovskite CsPbBr3 nanocrystals (CPB NCs) have been encapsulated into Pb-centered MOFs via simple wet-chemical self-sacrifice to construct a "turn-off" sensor for the sensitive detection of NH3·H2O or Fe3+ in aqueous solution. The Mott-Schottky plots (M-S), ultraviolet photoelectron spectroscopy (UPS) and density functional theory (DFT) calculation have proved the formation of p-n junction between the derived CsPbBr3 and parent Pb-MOF. The CPB⊆Pb-MOF heterojunction has provided a strong platform to maintain high fluorescence performance and stability in aqueous solution as sensor. It is found that the static quenching process has affected the detection of Fe3+. More importantly, the occurrence of dynamic quenching with electron transfer is also verified by fluorescence lifetime, in-situ X-ray photoelectron spectroscopy (XPS) analysis. The phase transfer has taken major reason when being introduced by NH3·H2O. Fortunately, the 0.4CPB⊆Pb-MOF has exhibited best analytical performance for NH3·H2O or Fe3+. What's more, it has been manufactured for the visual detection for NH3·H2O or Fe3+ in the real environmental water samples. Thereby, this perovskite based water detection system would broaden the application in point-to-point precise diagnostics.