Intermarriage of Halide Perovskites and Metal‐Organic Framework Crystals

Engineering Co3O4@3DOM LaCoO3 multistage-pore nanoreactor with superior SO2 resistance for toluene catalytic combustion

Sulfur dioxide poisoning is a significant factor in catalyst deactivation during the catalytic combustion of volatile organic compounds. In this study, we prepared the LaCoO3 and Co3O4 composite catalysts using both the Ship-in-Bottle and Building-Bottle-Around-Ship approaches. Three-dimensionally ordered macropores (3DOM LaCoO3) were utilized as nanoreactors to protect the active sites during the catalytic combustion of toluene, preventing SO2 poisoning. Additionally, we grew ZIF-67 confined in the nanoreactor to create a multistage-pore structure. The Co3O4@3DOM LaCoO3 catalysts exhibited excellent activity in the complete catalytic oxidation of toluene. Various characterization studies confirmed the presence of a significant number of Co3+ species and an abundance of surface weak acid sites in the Co3O4@3DOM LaCoO3 catalysts, which synergistically enhanced the conversion of VOCs at low temperatures. Notably, the multistage pore structure provided a favorable reaction environment, accelerating the adsorption and diffusion of toluene and intermediates, resulting in excellent sulfur resistance of the catalysts. Moreover, XPS analysis confirmed a strong interaction between Co3O4 and LaCoO3, promoting rapid electron transfer and increasing the activation of O2-. In situ DRIFTS experiments verified that toluene mainly follows the MvK mechanism over Co3O4@3DOM LaCoO3 catalysts, indicating the following reaction pathway: toluene adsorption → benzyl alcohol → benzaldehyde → benzoate → anhydride → CO2 and H2O.

Metal-organic framework (MOF)/C-dots and covalent organic framework (COF)/C-dots hybrid nanocomposites: Fabrications and applications in sensing, medical, environmental, and energy sectors

Developing new hybrid materials is critical for addressing the current needs of the world in various fields, such as energy, sensing, health, hygiene, and others. C-dots are a member of the carbon nanomaterial family with numerous applications. Aggregation is one of the barriers to the performance of C-dots, which causes luminescence quenching, surface area decreases, etc. To improve the performance of C-dots, numerous matrices including metal-organic frameworks (MOFs), covalent-organic frameworks (COFs), and polymers have been composited with C-dots. The porous crystalline structures, which are constituents of metal nodes and organic linkers (MOFs) or covalently attached organic units (COFs) provide privileged features such as high specific surface area, tunable structures, and pore diameters, modifiable surface, high thermal, mechanical, and chemical stabilities. Also, the MOFs and COFs protect the C-dots from the environment. Therefore, MOF/C-dots and COF/C-dots composites combine their features while retaining topological properties and improving performances. In this review, we first compare MOFs with COFs as matrices for C-dots. Then, the recent progress in developing hybrid MOFs/C-dots and COFs/C-dots composites has been discussed and their applications in various fields have been explained briefly.

Terbium alginate encapsulated CsPbI3@Pb-MOF: a ratiometric fluorescent bead for detection and adsorption of Fe3

Halide perovskite nanocrystals are innovative luminescent materials for fluorescent probes with high quantum yield and narrow emission bandwidth. However, the limited stability, single-signal response, and separation challenges obstruct their widespread use in water ion detection. Herein, a ratiometric fluorescence sensor based on terbium alginate gel beads (green fluorescent, namely Tb-AG) embedded with powdered CsPbI3@Pb-MOF (red fluorescent) was prepared for fluorescent determination and adsorption of Fe3+. Pb-MOF's protection notably enhances the water stability of CsPbI3, while the energy transfer between CsPbI3@Pb-MOF and Tb3+ elevates the optical performance of CsPbI3@Pb-MOF@Tb-AG. Significantly, Fe3+ markedly suppresses CsPbI3@Pb-MOF red fluorescence at 647 nm, while not noticeably affecting Tb-AG green emission at 528 nm. The sensor exhibited a strong linear response to Fe3+ concentrations ranging from 0 to 90 μM, with a detection limit of 0.44 μM and high selectivity. The CsPbI3@Pb-MOF@Tb-AG-based sensor has been effectively validated through its successful use in detecting Fe3+ in tap and river water samples. Furthermore, CsPbI3@Pb-MOF@Tb-AG demonstrates a notable adsorption capacity of 325.4 mg g-1 Fe3+. Finally, the mechanism of Fe3+ detection and adsorption was determined.

CsPbBr3 perovskite quantum dot decorated ZIF-8 MOF: a selective dual recognition fluorometric visual probe for 4-nitroaniline and rhodamine blue

The uses of highly luminescent perovskite quantum dots in real analytical detection were limited by their supersensitive nature. Here, we have designed a CsPbBr3 perovskite based fluorometric sensor by integrating them with a zeolitic imidazole framework (ZIF-8) via an in situ one step technique and established its stability in aqueous and other polar solvents. The CsPbBr3@ZIF-8 luminescence sensor functioned excellently for the trace detection of 4-nitroaniline and rhodamine blue dye molecules with a detection limit value of 8.367 ppb and 0.088 ppm, respectively. A comprehensive investigation found that the quenching of the fluorescence signal occurred via fluorescence resonance energy transfer (FRET) for rhodamine blue dye and a H-bonding interaction induced trap density mediated quenching mechanism was responsible for 4-NA detection. The potential of this suggested sensor as a cheap portable test paper probe for analyte detection was also explored. This study introduces CsPbBr3 as a cutting-edge sensing platform for industrial pollutants such as dye molecules and nitroaromatics.

PdS Quantum Dots as a Hole Attractor Encapsulated into the MOF@Cd0.5Zn0.5S Heterostructure for Boosting Photocatalytic Hydrogen Evolution under Visible Light

Herein, a new photocatalyst PdS@UiOS@CZS is successfully synthesized, where thiol-functionalized UiO-66 (UiOS), a metal-organic framework (MOF) material, is used as a host to encapsulate PdS quantum dots (QDs) in its cages, and Cd_0.5Zn_0.5S (CZS) solid solution nanoparticles (NPs) are anchored on its outer surface. The resultant PdS@UiOS@CZS with an optimal ratio between components displays an excellent photocatalytic H₂ evolution rate of 46.1 mmol h^-1 g^-1 under visible light irradiation (420∼780 nm), which is 512.0, 9.2, and 5.9 times that of pure UiOS, CZS, and UiOS@CZS, respectively. The reason for the significantly enhanced performance is that the encapsulated PdS QDs strongly attract the photogenerated holes into the pores of UiOS, while the photogenerated electrons are effectively migrated to CZS due to the heterojunction effect, thereby effectively suppressing the recombination of charge carriers for further high-efficiency hydrogen production. This work provides an idea for developing efficient photocatalysts induced by hole attraction.

Metal-Organic Frameworks: Molecules or Semiconductors in Photocatalysis?

In the realm of solids, metal-organic frameworks (MOFs) offer unique possibilities for the rational engineering of tailored physical properties. These derive from the modular, molecular make-up of MOFs, which allows for the selection and modification of the organic and inorganic building units that construct them. The adaptable properties make MOFs interesting materials for photocatalysis, an area of increasing significance. But the molecular and porous nature of MOFs leaves the field, in some areas, juxtapositioned between semiconductor physics and homogeneous photocatalysis. While descriptors from both fields are applied in tandem, the gap between theory and experiment has widened in some areas, and arguably needs fixing. Here we review where MOFs have been shown to be similar to conventional semiconductors in photocatalysis, and where they have been shown to be more like infinite molecules in solution. We do this from the perspective of band theory, which in the context of photocatalysis, covers both the molecular and nonmolecular principles of relevance.