Metal-Ion Coupling in Metal–Organic Framework Materials Regulating the Output Performance of a Triboelectric Nanogenerator

A Cu(I)-Based MOF with Nonlinear Optical Properties and a Favorable Optical Limit Threshold

The exploitation of high-performance third-order nonlinear optical (NLO) materials that have a favorable optical limit (OL) threshold is essential due to a rise in the application of ultra-intense lasers. In this study, a Cu-based MOF (denoted as Cu-bpy) was synthesized, and its third-order NLO and OL properties were investigated using the Z-scan technique with the nanosecond laser pulse excitation set at 532 nm. The Cu-bpy exhibits a typical rate of reverse saturable absorption (RSA) with a third-order nonlinear absorption coefficient of 100 cm GW-1 and a favorable OL threshold of 0.75 J cm-2 (at a concentration of 1.6 mg mL-1), which is lower than that of most NLO materials that have been reported on so far. In addition, a DFT calculation was performed and was in agreement with our experimental results. Furthermore, the mechanism of the third-order NLO properties was illustrated as one-photon absorption (1PA). These results investigate the relationship between the structure and the nonlinear optical properties of Cu-bpy, and provide an experimental and theoretical basis for its use in optical limiting applications.

MOFs-Based Materials with Confined Space: Opportunities and Challenges for Energy and Catalytic Conversion

Metal-Organic Frameworks (MOFs) are a very promising material in the fields of energy and catalysis due to their rich active sites, tunable pore size, structural adaptability, and high specific surface area. The concepts of "carbon peak" and "carbon neutrality" have opened up huge development opportunities in the fields of energy storage, energy conversion, and catalysis, and have made significant progress and breakthroughs. In recent years, people have shown great interest in the development of MOFs materials and their applications in the above research fields. This review introduces the design strategies and latest progress of MOFs are included based on their structures such as core-shell, yolk-shell, multi-shelled, sandwich structures, unique crystal surface exposures, and MOF-derived nanomaterials in detail. This work comprehensively and systematically reviews the applications of MOF-based materials in energy and catalysis and reviews the research progress of MOF materials for atmospheric water harvesting, seawater uranium extraction, and triboelectric nanogenerators. Finally, this review looks forward to the challenges and opportunities of controlling the synthesis of MOFs through low-cost, improved conductivity, high-temperature heat resistance, and integration with machine learning. This review provides useful references for promoting the application of MOFs-based materials in the aforementioned fields.

Innovative Synthesis of Zeolitic Imidazolate Framework by a Stovetop Kitchen Pressure Cook Pot for Triboelectric Nanogenerator

This study presents a novel approach utilizing solvothermal techniques to synthesize zeolitic imidazolate framework (ZIF‐4) particles. Various properties of the ZIF‐4 particles are investigated to shed light on the structural and morphological characteristics. These ZIF‐4 particles act as a positive triboelectric layer in the fabrication of a triboelectric nanogenerator (TENG) designed for powering electronic devices. The solvothermal‐assisted synthesis ensures the controlled and efficient production of ZIF‐4, optimizing its characteristics for enhanced performance in the TENG. The generated TENG, based on ZIF‐4 particles, determines promising capabilities in converting mechanical energy into electrical power. The highest power of TENG is obtained to be 18 μW at a load resistance of 50 MΩ. This work contributes major insights to the search for sustainable and effective power solutions for electronic gadgets. It emphasizes the potential of ZIF‐4 as a crucial triboelectric material, demonstrating its importance in the advancement of TENGs.

Third-Order Nonlinear Optical Modulation Behavior of Photoresponsive Bimetallic MOFs

Bimetallic metal-organic frameworks (MOFs) capable of sensing external stimuli will provide more possibilities for further regulating third-order nonlinear optical (NLO) properties. In this work, we synthesized bimetallic MOFs (ZnCu-MOF and ZnCd-MOF) through central metal exchange using a photoresponsive Zn-MOF as a precursor. Compared with Zn-MOF, both ZnCu-MOF and ZnCd-MOF exhibit significantly enhanced third-order NLO absorption properties. This is mainly attributed to the introduction of metal ions with different electron configurations that can adjust the bandgap of MOFs and enhance electron delocalization, thus promoting electron transfer. Interestingly, the bimetallic MOFs show a transition from reverse saturation absorption (RSA) to saturation absorption (SA) after exposure to ultraviolet irradiation, as they retain the properties of directional photogenerated electron transfer. Photoresponsive bimetallic MOFs not only have the effect of bimetallic modulation of electronic structures but also have the characteristics of photoinduced electron transfer, exhibiting diversified optical properties. These findings provide a novel method for the development of multifunctional NLO materials.

Crystalline Porous Material-Based Nanogenerators: Recent Progress, Applications, Challenges, and Opportunities

Nanogenerator (NG) is a potential technology that allows to build self-powered systems, sensors, flexible and portable electronics in the current Internet of Things (IoT) generation. Nanogenerators include piezoelectric nanogenerators (PENGs) and triboelectric nanogenerators (TENGs), convert different forms of mechanical motion into useful electrical signals. They have evolved and expanded their applications in various fields since their discovery in 2006 and 2012. Material selection is crucial for designing efficient NGs, with high conversion efficiencies. In the recent past, crystalline porous mat erials (metal-organic frameworks (MOFs) and covalent organic frameworks (COFs)) have been widely reported as potential candidates for nanogenerators, owing to their special properties of large surface area, porosity tailoring, ease of surface, post-synthesis modification, and chemical stability. The present organized review provides a complete overview of all the crystalline porous materials (CPMs)-based nanogenerator devices reported in the literature, including synthesis, characterization, device fabrication, and potential applications. Additionally, this review article discusses current challenges, future directions, and perspectives in the field of CPMs-NGs.

Cationic metal-organic framework with charge separation effect as a high output triboelectric nanogenerator material for self-powered anticorrosion

New stable frictional materials based on metal-organic frameworks (MOFs) are greatly desired for applications in self-powered systems. This work reports an ionic MOF material with efficient charge separation mediated by charge induction. ZUT-iMOF-1(Cu) is chemically stable and its triboelectric output performance surpasses those of traditional MOF materials. The short-circuit current of the iMOF triboelectric nanogenerator is 73.79 μA at 5 Hz. The output performance remains stable over 50 000 cycles of continuous operation. The charge and power densities peak at 123.20 μC m-2 and 3133.23 mW m-2. Owing to its high output performance, ZUT-iMOF-1(Cu) effectively prevents metal corrosion in cathodic-protection systems. Theoretical calculations show that increasing the charge-separation effect promotes the frictional electricity generation behaviour. This study provides research suggestions for ionic MOF frictional materials and will promote their application in self-powered electrochemical cathodic-protection systems.

Directional design of carboxylic acid coordination number fine-tuned space structure to improve the output performance of nanogenerators

The emergence of nanogenerators, which provide a way to obtain mechanical energy from the environment and to collect and transmit tiny amounts of energy, has attracted a lot of attention. MOFs, because of their diverse structures as well as stable pores and large specific surface area, have very significant advantages to be used as nanogenerator materials. In this paper, two MOFs with similar spatial structures are designed to take advantage of the different coordination numbers of carboxylic acids to achieve the regulation of their microstructures. The output performance of friction power generation was found to be affected significantly by their microstructures. The friction power generation performance improved with the increase of carboxylic acids, and the obtained polyacid ligand materials can be used for light bulb illumination, which is a step forward for the practical exploration.

Application of Metal–Organic Framework in Diagnosis and Treatment of Diabetes

Diabetes-related chronic wounds are often accompanied by a poor wound-healing environment such as high glucose, recurrent infections, and inflammation, and standard wound treatments are fairly limited in their ability to heal these wounds. Metal–organic frameworks (MOFs) have been developed to improve therapeutic outcomes due to their ease of engineering, surface functionalization, and therapeutic properties. In this review, we summarize the different synthesis methods of MOFs and conduct a comprehensive review of the latest research progress of MOFs in the treatment of diabetes and its wounds. State-of-the-art in vivo oral hypoglycemic strategies and the in vitro diagnosis of diabetes are enumerated and different antimicrobial strategies (including physical contact, oxidative stress, photothermal, and related ions or ligands) and provascular strategies for the treatment of diabetic wounds are compared. It focuses on the connections and differences between different applications of MOFs as well as possible directions for improvement. Finally, the potential toxicity of MOFs is also an issue that we cannot ignore.

Recent Development of Morphology-Controlled Hybrid Nanomaterials for Triboelectric Nanogenerator: A Review

Being cognizant of modern electronic devices, the scientists are continuing to investigate renewable green-energy resources for a decade. Amid different energy harvesting systems, the triboelectric nanogenerators (TENGs) have been found to be the most promising mechanical harvesting technology and have drawn attention to generate electrical energy. Thanks to its instant output power, choice to opt for wide-ranging materials, low maintenance cost, easy fabrication process and environmentally friendly nature. Due to numerous working modes of TENGs, it is dedicated to desired application at ambient conditions. In this review, an advance correlation of TENGs have been explained based on the variety of nanostructures, including 0D, 1D, 2D, 3D, metal organic frameworks (MOFs), coordination polymers (CPs), covalent organic frameworks (COFs), and perovskite materials. Moreover, an overview of previous and current perspectives of various nanomaterials, synthesis, fabrication and their applications in potential fields have been discussed in detail.