Defect Engineering Strategy for Superior Integration of Metal-Organic Framework and Halide Perovskite as a Fluorescence Sensing Material.

Combining halide perovskite quantum dots (QDs) and metal-organic frameworks (MOFs) material is challenging when the QDs' size is larger than the MOFs' nanopores. Here, we adopted a simple defect engineering approach to increase the size of zeolitic imidazolate framework 90 (ZIF-90)'s pores size to better load CH3NH3PbBr3 perovskite QDs. This defect structure effect can be easily achieved by adjusting the metal-to-ligand ratio throughout the ZIF-90 synthesis process. The QDs are then grown in the defective structure, resulting in a hybrid ZIF-90-perovskite (ZP) composite. The QDs in ZP composites occupied the gap of 10-18 nm defective ZIF-90 crystal and interestingly isolated the QDs with high stability in aqueous solution. We also investigated the relationship between defect engineering and fluorescence sensing, finding that the aqueous Cu2+ ion concentration was directly correlated to defective ZIF-90 and ZP composites. We also found that the role of the O-Cu coordination bonds and CH3NHCu+ species formation in the materials when they reacted with Cu2+ was responsible for this relationship. Finally, this strategy was successful in developing Cu2+ ion fluorescence sensing in water with better selectivity and sensitivity.

In situ formation of Co3O4 nanoparticles embedded N-doped porous carbon nanocomposite: a robust material for electrocatalytic detection of anticancer drug flutamide and supercapacitor application.

The one-step synthesis of heteroatom-doped porous carbons is reported with the in situ formation of cobalt oxide nanoparticles for dual electrochemical applications (i.e., electrochemical sensor and supercapacitor). A single molecular template of zeolitic imidazole framework-67 (ZIF-67) was utilized for the solid-state synthesis of cobalt oxide nanoparticle-decorated nitrogen-doped porous carbon (Co3O4@NPC) nanocomposite through a facile calcination treatment. For the first time, Co3O4@NPC nanocomposite derived from ZIF-67 has been applied as an electrode material for the efficient electrochemical detection of anticancer drug flutamide (FLU). The cyclic voltammetry studies were performed in the operating potential from 0.15 to - 0.65 V (vs. Ag/AgCl). Interestingly, the fabricated drug sensor exhibited a very low reduction potential (- 0.42 V) compared to other  reported sensors. The fabricated sensor exhibited good analytical performance in terms of low detection limit (12 nM), wide linear range (0.5 to 400 µM), and appreciable recovery results (~ 98%, RSD 1.7% (n = 3)) in a human urine sample. Hereafter, we also examined the supercapacitor performance of the Co3O4@NPC-modified Ni foam in a 1M KOH electrolyte, and noticeable a specific capacitance of 525 F g-1 at 1.5 A g-1 was attained, with long-term cycling stability. The Co3O4@NPC nanocomposite supercapacitor experiments outperform the associated MOF-derived carbons and the Co3O4-based nanostructure-modified electrodes.

Nitrogen-doped carbon quantum dots embedded Co3O4 with multiwall carbon nanotubes: An efficient probe for the simultaneous determination of anticancer and antibiotic drugs.

The simultaneous determination of anticancer and antibiotic drugs in biological samples with fast and sensitive methods is an essential task for the effective monitoring of drug therapy. A novel electrochemical sensor for the simultaneous determination of anticancer drug Flutamide (FLU) and antibiotic drug Nitrofurantoin (NF) was developed based on the glassy carbon electrode (GCE) modified with N-CQD@Co3O4/MWCNTs hybrid nanocomposite. The electro-kinetics of the developed sensor was studied using cyclic voltammetry (CV). The electrochemical performance of FLU and NF on the N-CQD@Co3O4/MWCNTs/GCE surface was examined using CV and differential pulse voltammetry (DPV) techniques. At an optimized condition, the developed sensor exhibits excellent performance in simultaneous determination of FLU and NF with a linear range of 0.05-590 µM and 0.05-1220 µM and detection limit of 0.0169 µM and 0.044 µM respectively. Furthermore, the developed sensor exhibits satisfactory results in the real sample analysis.