Novel SnO₂@Cu₃(BTC)₂ Composites as a Highly Efficient Photocatalyst and Fluorescent Sensor

A novel SnO₂@Cu₃(BTC)₂ composite was synthesized using a quick and affordable bottom-up approach via impregnation of SnO₂ nanoparticles into the porous Cu₃(BTC)₂ metal-organic framework (MOF). This composite material is characterized by Fourier transform infrared (FTIR) spectroscopy, powder X-ray diffraction (PXRD) spectra, scanning electron microscope (SEM) analysis, and energy-dispersive X-ray spectroscopy (EDS) analysis. SnO₂@Cu₃(BTC)₂ degraded the methylene blue (MB) dye within 80 min under sunlight with a maximum degradation efficiency of 85.12%. This composite easily recyclable up to five cycles with the retention of its MB degradation efficiency. Moreover, SnO₂@Cu₃(BTC)₂ can be also used efficiently for fast sensing of 2,4,6-trinitrophenol (TNP) in water with noticeable turn-off quenching response. Its limits of detection (LOD) for TNP was 2.82 µM with enhanced selectivity toward TNP (over other NACs) as verified by competitive nitro explosive tests. Density functional theory (DFT) calculations and spectral overlap were used to assess the sensing mechanism. This composite fluorescent sensing system for TNP are demonstrated to have high selectivity and sensitivity. Our findings imply that the prepared low cost SnO₂@Cu₃(BTC)₂ composite can be used as a superior fluorescence sensor and photo catalyst for large scale industrial applications.