Stretchable and Shape-Adaptable Triboelectric Nanogenerator Based on Biocompatible Liquid Electrolyte for Biomechanical Energy Harvesting and Wearable Human–Machine Interaction

The significant demand of sustainable power sources has been triggered by the development of wearable electronics (e.g., electronic skin, human health monitors, and intelligent robotics). However, tensile strain limitation and low conformability of existing power sources cannot match their development. Herein, a stretchable and shape-adaptable liquid-based single-electrode triboelectric nanogenerator (LS-TENG) based on potassium iodide and glycerol (KI-Gly) liquid electrolyte as work electrode is developed for harvesting human motion energy to power wearable electronics. The LS-TENG demonstrates high output performances (open-circuit voltage of 300 V, short-circuit current density of 17.5 mA m^–2, and maximum output power of 2.0 W m^–2) and maintains the stable output performances without deterioration under 250% tension stretching and after 10 000 cycles of repeated contact-separation motion. Moreover, the LS-TENG can harvest biomechanical energy, including arm shaking, human walking, and hand tapping, to power commercial electronics without extra power sources. The LS-TENG attached on different joints of body enables to work as self-powered human motion monitor. Furthermore, a flexible touch panel based on the LS-TENG combined with a microcontroller is explored for human–machine interactions. Consequently, the stretchable and shape-adaptable LS-TENG based on KI-Gly electrolyte would act as an exciting platform for biomechanical energy harvesting and wearable human–machine interaction.     

Self-Assembled Nanoporous Metal–Organic Framework Monolayer Film for Osmotic Energy Harvesting

Osmotic energy represents a promising energy resource because it is sustainable and environmentally benign. Subnanoscale channels are considered as a competitive platform for generating this blue energy due to their highly selective and ultrafast ion transport. However, fabricating functional subnanochannels capable of high energy output remains challenging. Here, a heterogeneous subnanochannel membrane formed by coating a functionalized self-assembled metal−organic framework (MOF) monolayer (SAMM) film on a porous anodic aluminum oxide membrane, is reported. The SAMM film, with a thickness of ≈160 nm, is fabricated by self-assembly of poly(methyl methacrylate-co-vinylimidazole)-modified UiO-66-NH₂ nanoparticles at the water−air interface. In the SAMM, imidazole and NH₂ groups provide abundant positive charges, while the angstrom-scale windows act as ionic filters for selective screening of anions with different hydration diameters. As a result, the heterogeneous membrane exhibits excellent capacity for anion-selective transport, which contributes to an optimal osmotic power of 6.76 W m⁻² under a 100-fold NaCl gradient, as well as a high Cl⁻/SO₄²⁻ selectivity of ≈42.2. Further, the output power is increased to 10.5 W m⁻² by methylating imidazole moieties on the MOF surface. This work provides a facile and modular approach to fabricate subnanochannels for enabling highly selective and efficient osmotic energy conversion.     

New-Generation Anion-Pillared Metal–Organic Frameworks with Customized Cages for Highly Efficient CO2 Capture

The rational design of porous materials for CO₂ capture under realistic process conditions is highly desirable. However, trade-offs exist among a nanopore's capacity, selectivity, adsorption heat, and stability. In this study, a new generation of anion-pillared metal-organic frameworks (MOFs) are reported with customizable cages for benchmark CO₂ capture from flue gas. The optimally designed TIFSIX-Cu-TPA exhibits a high CO₂ capacity, excellent CO₂/N₂ selectivity, high thermal stability, and chemical stability in acid solution and acidic atmosphere, as well as modest adsorption heat for facile regeneration. Additionally, the practical separation performance of the synthesized MOFs is demonstrated by breakthrough experiments under various process conditions. A highly selective separation is achieved at 298–348 K with the impressive CO₂ capacity of 2.1–1.4 mmol g⁻¹. Importantly, the outstanding performance is sustained under high humidity and over ten repeat process cycles. The molecular mechanism of MOF's CO₂ adsorption is further investigated in situ by CO₂ dosed single crystal structure and theoretical calculations, highlighting two separate binding sites for CO₂ in small and large cages featured with high CO₂ selectivity and loading, respectively. The simultaneous adsorption of CO₂ inside these two types of interconnected cages accounts for the high performance of these newly designed anionic pillar-caged MOFs.     

Novel Metal–Organic Framework Cocrystal Strategy for Significantly Enhancing Photocatalytic Performance

Owing to their high carrier recombination speed and low spectral utilization, it is difficult to further improve the performance of photocatalysts. In this study, a novel metal–organic framework (MOF) self-assembled cocrystal material is developed. The guest molecule is inserted and self-assembled with the existing MOF ligand to form an organic cocrystal. The highly ordered molecular arrangement and tight intermolecular distances between donor and acceptor molecules promote a strong π–π charge transfer interaction, facilitating the migration and separation of photogenerated charge carriers. In addition, efficient redshifts in the absorption wavelength enhance the response to visible light. Further, the unique porous structure of MOFs is beneficial for increasing the interfacial area of photocatalytic reactions, and metal ions can become the center of photogenerated carrier capture, effectively inhibiting carrier recombination. Consequently, the MOF cocrystal demonstrates remarkable efficiency in the degradation of pollutants in water, achieving a noteworthy removal efficiency of 95.31% within 15 min. Moreover, the photocatalyic reaction kinetics constant of the MOF cocrystal is 46.5 times higher, indicating the success of this new strategy in developing highly efficient photocatalytic systems.     

Pristine Metal–Organic Frameworks and their Composites for Renewable Hydrogen Energy Applications

Metal–organic frameworks (MOFs) have emerged as ideal multifunctional platforms for renewable hydrogen (H₂) energy applications owing to their tunable chemical compositions and structures and high porosity. Their advanced component species and porous structure contribute greatly to the enhanced activity, electrical conductivity, photo response, charge-hole separation efficiency, and structural stability of MOF materials, which are promising for practical H₂ economy. In this review, we mainly introduce design strategies for the enhancement of electro-/photochemical behaviors or adsorption performance of porous MOF materials for H₂ production, storage, and utilization from compositional perspective. Following these engineering strategies, the correlation between composition and property-structure-performance of pristine MOFs and their composite with advanced components is illustrated. Finally, challenges and directions of future development of related MOFs and MOF composites for H₂ economy are provided.     

Introducing Metal–Organic Frameworks to Melt Electrowriting: Multifunctional Scaffolds with Controlled Microarchitecture for Tissue Engineering Applications

Scaffolds with multiple advantageous biological and structural properties are still a challenge in the field of tissue engineering. The convergence of advanced fabrication techniques and functional materials is key to fulfill this need. Melt electrowriting (MEW) is an additive manufacturing technique that enables the fabrication of microfibrous scaffolds with precisely defined microarchitectures. Here, it is proposed to exploit metal–organic frameworks (MOFs) to efficiently introduce multifunctionalities by combining polycaprolactone (PCL), the gold standard material in MEW, with a silver-/silver-chloride-decorated iron-based MOF (NH₂-MIL-88B(Fe)). This results in highly ordered constructs with antibacterial properties and magnetic resonance imaging (MRI) visibility. Scaffolds with up to 20 wt% MOF are successfully melt-electrowritten with a fiber diameter of 50 µm. Among these, 5 wt% MOF proves to be the optimal concentration as it exhibits silver-induced sustained antibacterial efficacy while maintaining PCL cytocompatibility and in vitro immune response. The iron component of the MOF (Fe(III) nodes) renders the composite visible with MRI, thereby enabling scaffold monitoring upon implantation with a clinically accepted method. The combination of MEW and MOFs as tunable additives and cargo carriers opens the way for designing advanced multifunctional scaffolds with a wide range of applications in, e.g., tissue engineering, biosensing and drug delivery.     

A Feature-Scale Greenwood–Williamson Model for Metal Chemical Mechanical Planarization

In this work, a new feature-scale model is proposed for investigating the interaction between the wafer pattern and individual pad asperities in the process of chemical mechanical planarization (CMP). Based on the contact mechanics equation and the modified Greenwood–Williamson (GW) model which captures the evolution of feature curvature and the modification of the pad asperity height distribution, the discrete convolution and fast Fourier transform (DC-FFT) technique is adopted and combined with the Picard iteration method to calculate the direct contact pressure distribution between the wafer surface and the polishing pad. The computed pressure is then used to determine the local removal rate of the underlying patterns and predict the evolution of the wafer surface profile. Furthermore, the method is extended to capture the metal dishing as the feature size changes. It is shown that the present model can avoid the false simulated results produced by directly applying the original GW model for CMP when the feature size approaches zero. Otherwise, the calculated surface profile and dishing values of pattern geometries are in good agreement with the experimental data. Therefore, this model can not only be used to simulate the evolution of the wafer surface for global planarization at lower technology nodes, but can also be applied to provide some basic design rules for improving the process parameters and reducing the time and cost for developing new architectures.     

Donor–Acceptor-Type Organic-Small-Molecule-Based Solar-Energy-Absorbing Material for Highly Efficient Water Evaporation and Thermoelectric Power Generation

Recently, owing to the great structural tunability, excellent photothermal property, and strong photobleaching resistance, organic-small-molecule photothermal materials are proposed as promising solar absorbent materials. Herein, through fusing two strong electron-withdrawing units dibenzo[f,h]quinoxaline and anthraquinone units, a rigid planar acceptor dibenzo[a,c]naphtho[2,3-h]phenazine-8,13-dione (PDN) with stronger electron-withdrawing ability is obtained and used to construct donor–acceptor-type organic-small-molecule solar-energy-absorbing material, 2,17-bis(diphenylamino)dibenzo[a,c]naphtho[2,3-h]phenazine-8,13-dione (DDPA-PDN). The new compound exhibits a strong intramolecular charge transfer character and conjugates rigid plane skeleton, endowing it with a broadband optical absorption from 300 to 850 nm in the solid state, favorable photothermal properties, high photothermal conversion ability, and good photobleaching resistance. Under laser irradiation at 655 nm, the solid photothermal conversion efficiency of the resulting DDPA-PDN molecule reaches 56.23%. Additionally, DDPA-PDN-loaded cellulose papers equipped with abundant microchannels for water flow are integrated with thermoelectric devices, thus achieving an evaporation rate and voltage as high as 1.07 kg m⁻² h⁻¹ and 83 mV under 1 kW m⁻² solar irradiation, respectively. This study demonstrates the application of photothermal organic-small-molecules in water evaporation and power generation, therefore offering a valuable prospect of their utilization in solar energy harvesting.     

A Conductive 2D Conjugated Tetrathia[8]circulene-Based Nickel Metal–Organic Framework for Energy Storage

Herein, a novel D₄ symmetrical redox-active ligand tetrathia[8]circulene-2,3,5,6,8,9,11,12-octaol (8OH-TTC) is designed and synthesized, which coordinates with Ni²⁺ ions to construct a 2D conductive metal-organic framework (2D c-MOF) named Ni-TTC. Ni-TTC exhibits typical semiconducting properties with electrical conductivity up to ≈1.0 S m⁻¹ at 298 K. Furthermore, magnetism measurements show the paramagnetic property of Ni-TTC with strong antiferromagnetic coupling due to the presence of semiquinone ligand radicals and Ni²⁺ sites. In virtue of its decent electrical conductivity and good redox activity, the gravimetric capacitance of Ni-TTC is up to 249 F g⁻¹ at a discharge rate of 0.2 A g⁻¹, which demonstrates the potential of tetrathia[8]circulene-based redox-active 2D c-MOFs in energy storage applications.     

Electronic Modulation of Metal–Organic Frameworks by Interfacial Bridging for Efficient pH-Universal Hydrogen Evolution

Designing well-defined interfacial chemical bond bridges is an effective strategy to optimize the catalytic activity of metal–organic frameworks (MOFs), but it remains challenging. Herein, a facile in situ growth strategy is reported for the synthesis of tightly connected 2D/2D heterostructures by coupling MXene with CoBDC nanosheets. The multifunctional MXene nanosheets with high conductivity and ideal hydrophilicity as bridging carriers can ensure structural stability and sufficient exposure to active sites. Moreover, the Co–O–Ti bond bridging formed at the interface effectively triggers the charge transfer and modulates the electronic structure of the Co-active site, which enhances the reaction kinetics. As a result, the optimized CoBDC/MXene exhibits superior hydrogen evolution reaction (HER) activity with low overpotentials of 29, 41, and 76 mV at 10 mA cm⁻² in alkaline, acidic, and neutral electrolytes, respectively, which is comparable to commercial Pt/C. Theoretical calculation demonstrates that the interfacial bridging-induced electron redistribution optimizes the free energy of water dissociation and hydrogen adsorption, resulting in improved hydrogen evolution. This study not only provides a novel electrocatalyst for efficient HER at all pH conditions but also opens up a new avenue for designing highly active catalytic systems.     

Disclosing the Role of Defect-Engineered Metal–Organic Frameworks in Mixed Matrix Membranes for Efficient CO2 Separation: A Joint Experimental-Computational Exploration

Incorporation of defects in metal–organic frameworks (MOFs) offers new opportunities for manipulating their microporosity and functionalities. The so-called “defect engineering” has great potential to tailor the mass transport properties in MOF/polymer mixed matrix membranes (MMMs) for challenging separation applications, for example, CO₂ capture. This study first investigates the impact of MOF defects on the membrane properties of the resultant MOF/polymer MMMs for CO₂ separation. Highly porous defect-engineered UiO-66 nanoparticles are successfully synthesized and incorporated into a CO₂-philic crosslinked poly(ethylene glycol) diacrylate (PEGDA) matrix. A thorough joint experimental/simulation characterization reveals that defect-engineered UiO-66/PEGDA MMMs exhibit nearly identical filler–matrix interfacial properties regardless of the defect concentrations of their parental UiO-66 filler. In addition, non-equilibrium molecular dynamics simulations in tandem with gas transport studies disclose that the defects in MOFs provide the MMMs with ultrafast transport pathways mainly governed by diffusivity selectivity. Ultimately, MMMs containing the most defective UiO-66 show the most enhanced CO₂/N₂ separation performance—CO₂ permeability = 470 Barrer (four times higher than pure PEGDA) and maintains CO₂/N₂ selectivity = 41—which overcomes the trade-off limitation in pure polymers. The results emphasize that defect engineering in MOFs would mark a new milestone for the future development of optimized MMMs.     

A Dual−Functional Cationic Covalent Organic Frameworks Modified Separator for High Energy Lithium Metal Batteries

Separator modification is an efficient strategy to handle with the challenges of lithium metal batteries but its success is primarily subject to the modification of the materials. Herein, a cationic covalent organic framework (COF) composed of positively charged organic units and weakly bonded fluoride ions (F⁻) is introduced to modify the commercial polypropylene separator (COF−F@PP). It is found that the organic unit has abundant nanopores to homogenize the lithium ions (Li⁺) flux and can interact with electrolyte solvent molecules to form a desolvation structure of Li⁺. Meanwhile, the F⁻ within the nanopores is proved to assist in building a robust LiF−riched solid electrolyte interphase to avoid the side reactions between lithium anode and electrolyte. Hence, the COF−F@PP delivers feasible practicality for the outstanding cycling stability, high Coulombic efficiency, and superior rate capability of Li//LFP coin cell at 5 C, low N/P ratio (2.19) full cell, and pouch cell at 1 C.     

An Energy Efficient OFDM–MIMO Systems for Multimedia Data Transmission Based on Hybrid Fuzzy Approach

Wireless Personal Communications - At present the low cost, low power and collaborative feature of Wireless Sensor Network (WSN) is becoming a popular communication technology in smart grid...     

MEM-DnP—A Novel Energy Efficient Approach for Memory Integrity Detection and Protection in Embedded Systems

The pervasiveness of modern day embedded systems has led to the storing of huge amounts of sensitive information in them. These embedded devices often have to operate under insecure environments and are hence susceptible to software and physical attacks. Thus, security has been and will remain one of the prime concerns in the embedded systems. Although a lot of hardware and software techniques have been proposed to provide high levels of security, they are hampered by the trade-offs created by the design constraints in embedded systems. This paper presents a novel energy efficient approach for MEMory integrity Detection and Protection (MEM-DnP). The key feature of the proposed MEM-DnP is that it can be adaptively tuned to a memory integrity verification module by using a sensor module. This significantly reduces the energy overheads imposed on an embedded system as compared to the conventional memory integrity verification mechanisms. The simulation results show that the average energy saved in the combined detection and protection mechanism ranges from 85.5 % to 99.998 %. This is substantially higher compared to the results achieved in basecase simulations with traditional memory integrity verification techniques.     

Automata Based Hybrid PSO–GWO Algorithm for Secured Energy Efficient Optimal Routing in Wireless Sensor Network

The main objective in wireless sensor networks is to exploit efficiently the sensor nodes and to prolong the lifetime of the network. The discussion of energy is a significant concern to extend the lifetime of the network. Moreover, a nature inspired hybrid optimization approach called hybrid Particle Swarm Optimization–Grey Wolf Optimizer (PSO–GWO) is used in this work to efficiently utilize the energy and to transmit the data securely in an augmented path. A Learning Dynamic Deterministic Finite Automata (LD²FA) has been innovated and initiated to learn the dynamic role of the environment. LD²FA is mainly used to provide the learned and accepted string to hybrid PSO–GGWO so that the routes are optimized. Hybrid PSO–GWO is used to choose the optimal next node for each path to obtain the optimal route. The simulation results are obtained in MATLAB for 100–700 sensor nodes in a region of 500 × 500 m² which demonstrate that the proposed LD²FA based Hybrid PSO–GWO algorithm obtains better results when compared with existing algorithms. It is observed that LD²FA based Hybrid PSO–GWO has an increase of 18% and 48% betterment in lifetime of the network than PSO and GLBCA, nearly 57% and 75% increase in network lifetime when compared with GA and LDC respectively. It also shows an improvement of 24% increase compared to cluster-based IDS, nearly a rise of 90% throughput when compared with lightweight IDS. The consumption of energy is reduced by 13% and 15% than PSO and GA and an increase of 15% utilization of energy than LDC. Therefore, LD²FA based Hybrid PSO–GWO is been considered to efficiently utilize energy in an optimal route.

     

Inorganic–Organic Hybrid Dielectrics for Energy Conversion: Mechanism,Strategy, and Applications

Dielectric materials with higher energy storage and electromagnetic (EM) energy conversion are in high demand to advance electronic devices, military stealth, and mitigate EM wave pollution. Existing dielectric materials for high-energy-storage electronics and dielectric loss electromagnetic wave absorbers are studied toward realizing these goals, each aligned with the current global grand challenges. Libraries of dielectric materials with desirable permittivity, dielectric loss, and/or dielectric breakdown strength potentially meeting the device requirements are reviewed here. Regardless, aimed at translating these into energy storage devices, the oft-encountered shortcomings can be caused by either of two confluences: a) low permittivity, high dielectric loss, and low breakdown strength; b) low permittivity, low dielectric loss, and process complexity. Contextualizing these aspects and the overarching objectives of enabling high-efficiency energy storage and EM energy conversion, recent advances in by-design inorganic–organic hybrid materials are reviewed here, with a focus on design approaches, preparation methods, and characterization techniques. In light of their strengths and weaknesses, potential strategies to foster their commercial adoption are critically interrogated.     

Mechanochemical Post-Synthesis of Metal–Organic Framework-Based Pre-Electrocatalysts with Surface Fe?O?Ni/Co Bonding for Highly Efficient Oxygen Evolution

Rational surface engineering of metal–organic frameworks (MOFs) provide potential opportunities to address the sluggish kinetics of oxygen evolution reaction (OER). However, the development of MOF-based materials with low overpotentials remains a great challenge. Herein, a post-synthesis strategy to prepare highly efficient MOF-based pre-electrocatalysts via all-solid-phase mechanochemistry is demonstrated. The surface of a Fe-based MOF (MIL-53) can be reconstructed and anchored with atomically dispersed Ni/Co sites. As expected, the optimized M-NiA-CoN exhibits a very low overpotential of 180 mV at 10 mA cm⁻² and a small Tafel slope of 41 mV dec⁻¹ in 1 m KOH electrolyte. The superior electrocatalytic OER activity is mainly due to the formation of surface Fe O Ni/Co bonding. Furthermore, density functional theory calculations reveal that the transformation from ^*OH to ^*O is the rate-determining step and the electrocatalytic OER activity trend at different metal sites is Co > Ni≈Fe.     

Electrically Conductive Metal–Organic Framework Thin Film-Based On-Chip Micro-Biosensor: A Platform to Unravel Surface Morphology-Dependent Biosensing

Electrically conductive metal–organic frameworks (EC-MOFs) are suitable for electrochemical sensing because of their unique structure and properties. Herein, an on-chip electrochemical micro-biosensor is designed to study the electrocatalytic interfaces, which are generally buried between the solid support and liquid electrolyte in conventional electrochemical sensing methods. The gas–liquid interfacial reaction method is used to obtain a Cu-benzenehexathiol (Cu-BHT) thin film with a flat up-side surface and synaptic-like structure on the bottom-side surface. The effect of surface morphology on the film sensing performance is studied using the prepared Cu-BHT film-based on-chip micro-biosensor. The bottom-side surface exhibited significantly higher H₂O₂ sensing performance than that of the smooth up-side surface. The synaptic-like structure has dense crystal defects (ts-Cu), which act as nanozymes and play an important role in improving the H₂O₂ sensing performance. This study clarifies the role of crystal defects in Cu-BHT sensing using the micro-biosensor and allows the in-situ study of electrochemical interface of EC-MOF films during biosensing.     

The Role of Defects in Metal–Organic Frameworks for Nitrogen Reduction Reaction: When Defects Switch to Features

The electrochemical nitrogen reduction reaction (NRR), a contributor for producing ammonia under mild conditions sustainably, has recently attracted global research attention. Thus far, the design of highly efficient electrocatalysts to enhance NRR efficiency is a specific focus of the research. Among them, defect engineering of electrocatalysts is considered a significant way to improve electrocatalytic efficiency by regulating the electronic state and providing more active sites that can give electrocatalysts better physicochemical properties. Recently, metal–organic frameworks (MOFs), along with their derivatives, have captured immense interest in electrocatalytic reactions owing to not only their large surface area and high porosity but also the ability to create rich defects in their structures. Hence, they can provide plenty of exposed active sites for electron transfer, NN cleavage, and N₂ adsorption to enhance NRR performance. Herein, the concept, the in situ characterizations techniques for defects, and the most common ways to create defects into MOFs have been summarized. Furthermore, the recent advances of MOF-based electrocatalysts towards NRR have been recapitulated. Ultimately, the major challenges and outlook of defects in MOFs for NRR are proposed. This paper is anticipated to provide critical guidelines for optimizing NRR electrocatalysts.