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Anthraquinone-based hollow COFs were synthesized via a template-assisted method involving polystyrene nanospheres as the hard template, which enabled doubling the specific capacitance and energy density compared to non-templated COFs. Our approach can be extended to other COFs, offering a promising strategy for enhancing the performance of COF-based electrodes in energy storage applications. [ABSTRACT FROM AUTHOR]

Aqueous zinc‐ion hybrid supercapacitors (Zn‐HSCs) are promising devices for sustainable and efficient energy storage. However, they suffer from a limited energy density compared to lithium‐ion batteries. This limitation can be overcome by developing novel electrode materials, with covalent organic frameworks (COFs) standing out as a particularly intriguing option. Herein, peri‐xanthenoxanthene (PXX) has been integrated for the first time into a COF scaffold to take advantage of its straightforward synthesis, chemical stability, π‐conjugated backbone, and heteroatom content endowing reversible redox reactions at low potentials. Two novel hexagonal COFs have been designed and synthesized by tethering of a PXX‐diamine unit having a C2 symmetry with two distinct tris‐aldehydes acting as C3‐symmetric cornerstones, i.e., triformyl benzene (TFB) and triformylphloroglucinol (Tp), ultimately yielding COF PXX(PhNH2)2‐TFB and COF PXX(PhNH2)2‐Tp, respectively. As cathodes in Zn‐HSCs, COF PXX(PhNH2)2‐Tp exhibits a remarkable specific capacitance, energy, and power densities (237 F g−1, 106.6 Wh kg−1, and 3.0 kW kg−1, respectively), surpassing those of COF PXX(PhNH2)2‐TFB (109 F g−1, 49.1 Wh kg−1, and 0.67 kW kg−1). Importantly, both COFs display outstanding long‐term stability, over 5000 charge/discharge cycles, with capacitance retention >92%. These findings underscore the potential of PXX‐based COFs as high‐performance cathode materials for HSCs, thereby offering a promising new avenue for energy storage technologies. [ABSTRACT FROM AUTHOR]

Zinc hybrid supercapacitors (Zn‐HSCs) hold immense potential toward the next‐generation energy storage systems, effectively spanning the divide between conventional lithium‐ion batteries (LIBs) and supercapacitors. Unfortunately, the energy density of most of Zn‐HSCs has not yet rivalled the levels observed in LIBs. The electrochemical performance of aqueous Zn‐HSCs can be enhanced through the chemical functionalization of graphene‐based cathode materials with thiol moieties as they will be highly suitable for favoring Zn2+ adsorption/desorption. Here, a single‐step reaction is employed to synthesize thiol‐functionalized reduced graphene oxide (rGOSH), incorporating both oxygen functional groups (OFGs) and thiol functionalities, as demonstrated by X‐ray photoelectron spectroscopy (XPS) studies. Electrochemical analysis reveals that rGOSH cathodes exhibit a specific capacitance (540 F g−1) and specific capacity (139 mAh g−1) at 0.1 A g−1 as well as long‐term stability, with over 92% capacitance retention after 10 000 cycles, outperforming chemically reduced graphene oxide (CrGO). Notably, rGOSH electrodes displayed an exceptional maximum energy density of 187.6 Wh kg−1 and power density of 48.6 kW kg−1. Overall, this study offers an unprecedented powerful strategy for the design and optimization of cathode materials, paving the way for efficient and sustainable energy storage solutions to meet the increasing demands of modern energy applications. [ABSTRACT FROM AUTHOR]

Supercapacitors and transistors are two key devices for future electronics that must combine portability, high performance, easy scalability, etc. Graphene‐related materials (GRMs) are frequently chosen as active materials for these applications given their unique physical properties that are tunable via chemical functionalization. Up to date, among GRMs, only reduced graphene oxide (rGO) showed sufficient versatility and processability in mild media, rendering it suitable for integration in these two types of devices. Here, a sound alternative to rGO is provided, namely graphene acetic acid (GAA), whose physico‐chemical features offer specific advantages. In particular, the use of a GAA‐based cathode in a zinc hybrid supercapacitor (Zn‐HSC) delivers state‐of‐the‐art gravimetric capacitance of ≈400 F g−1 at a current density of 0.05 A g−1. Conversely, GAA‐based LGT, supported onto Si/SiO2, shows an ambipolar behavior in 0.1 m NaCl, featuring a clear p‐doping quantified by Dirac voltage higher than 100 mV. Such a device is successfully implemented in paper fluidics, thereby demonstrating the feasibility of real‐time monitoring. [ABSTRACT FROM AUTHOR]

Core–shell MOF@COF hybrids were synthesized via subsequent modification of MOF UiO-66-NH2 with 1,3,5-triformylphloroglucinol (TFP) and 2,3,5,6-tetraaminobenzoquinone (TABQ). The hybrids exhibited significant surface area (236 m2 g−1) and outstanding electrochemical performance (103 F g−1 at 0.5 A g−1), surpassing both COFs and MOFs, thereby showcasing the potential of on-surface condensation reactions for developing high-performance energy storage devices. [ABSTRACT FROM AUTHOR]

Organic materials represent a promising alternative to critical raw materials for energy storage applications due to their sustainable production combined with tunable structures and functionalities. Unfortunately, the biggest limitation of organic materials is their high solubility in aqueous electrolytes, which results in a poor cycling stability. Metal–organic polymers (MOPs) have emerged as versatile organic materials, which exhibit enhanced chemical stability as well as redox activity depending on the employed building units. Here, by mastering a coordination chemistry approach, two novel MOPs were synthesized via a coordination process between tetraminobenzoquinone (TABQ) and a metal ion (i.e., zinc or copper) and were explored as cathode materials for aluminum-ion batteries. The resulting Zn-TABQ MOP exhibited superior electrochemical performance compared to other common cathode materials in Al-batteries. Specifically, Zn-TABQ revealed a specific capacity of 198 mA h g−1 at 0.05 A g−1, combined with high-capacity retention (92%) after 5000 cycles at a scan rate of 1 A g−1 and an outstanding energy density of 247 W h kg−1. We demonstrated via ex situ characterization that the electrochemically active carbonyl (C＝O) units of Zn-TABQ coordinate with AlCl2+ and EMIM+ ions, thereby governing the mechanism of ion storage and release by taking advantage of the nature of the reversible interaction. [ABSTRACT FROM AUTHOR]

The unique electrochemical properties of polyoxometalates (POMs) render them ideal components for the fabrication of next‐generation high‐performance energy storage systems. However, their practical applications have been hindered by their high solubility in common electrolytes. This problem can be overcome by the effective hybridization of POMs with other materials. Here we present the design and synthesis of two novel polyoxometalate‐covalent organic frameworks (POCOF) via one‐pot solvothermal strategy between an amino‐functionalized Anderson‐type POM and a trialdehyde‐based building unit. We show that structural and functional complexity can be enriched by adding hydroxyl groups in the 2,4,6 position to the benzene‐1,3,5‐tricarbaldehyde allowing to exploit for the first time in POCOFs the keto‐enol tautomerization as additional feature to impart greater chemical stability to the COFs and enhanced properties leading to large specific surface area (347 m2/g) and superior electrochemical performance of the POCOF‐1 electrodes, when compared with POCOF‐2 electrodes that possess only imine‐type linkage and with pristine POM electrodes. Specifically, POCOF‐1 electrodes display remarkable specific, areal, and volumetric capacitance (125 F/g, 248 mF/cm2 and 41.9 mF/cm3, respectively) at a current density of 0.5 A/g, a maximum energy density (56.2 Wh/kg), a maximum power density (3.7 kW/kg) and an outstanding cyclability (90 % capacitance retention after 5000 cycles). [ABSTRACT FROM AUTHOR]

The unique electrochemical properties of polyoxometalates (POMs) render them ideal components for the fabrication of next‐generation high‐performance energy storage systems. However, their practical applications have been hindered by their high solubility in common electrolytes. This problem can be overcome by the effective hybridization of POMs with other materials. Here we present the design and synthesis of two novel polyoxometalate‐covalent organic frameworks (POCOF) via one‐pot solvothermal strategy between an amino‐functionalized Anderson‐type POM and a trialdehyde‐based building unit. We show that structural and functional complexity can be enriched by adding hydroxyl groups in the 2,4,6 position to the benzene‐1,3,5‐tricarbaldehyde allowing to exploit for the first time in POCOFs the keto‐enol tautomerization as additional feature to impart greater chemical stability to the COFs and enhanced properties leading to large specific surface area (347 m2/g) and superior electrochemical performance of the POCOF‐1 electrodes, when compared with POCOF‐2 electrodes that possess only imine‐type linkage and with pristine POM electrodes. Specifically, POCOF‐1 electrodes display remarkable specific, areal, and volumetric capacitance (125 F/g, 248 mF/cm2 and 41.9 mF/cm3, respectively) at a current density of 0.5 A/g, a maximum energy density (56.2 Wh/kg), a maximum power density (3.7 kW/kg) and an outstanding cyclability (90 % capacitance retention after 5000 cycles). [ABSTRACT FROM AUTHOR]

Transition metal carbides and nitrides (MXenes) are an emerging class of 2D materials, which are attracting ever‐growing attention due to their remarkable physicochemical properties. The presence of various surface functional groups on MXenes' surface, e.g., F, O, OH, Cl, opens the possibility to tune their properties through chemical functionalization approaches. However, only a few methods have been explored for the covalent functionalization of MXenes and include diazonium salt grafting and silylation reactions. Here, an unprecedented two‐step functionalization of Ti3C2Tx MXenes is reported, where (3‐aminopropyl)triethoxysilane is covalently tethered to Ti3C2Tx and serves as an anchoring unit for subsequent attachment of various organic bromides via the formation of CN bonds. Thin films of Ti3C2Tx functionalized with linear chains possessing increased hydrophilicity are employed for the fabrication of chemiresistive humidity sensors. The devices exhibit a broad operation range (0–100% relative humidity), high sensitivity (0.777 or 3.035), a fast response/recovery time (0.24/0.40 s ΔH−1, respectively), and high selectivity to water in the presence of saturated vapors of organic compounds. Importantly, our Ti3C2Tx‐based sensors display the largest operating range and a sensitivity beyond the state of the art of MXenes‐based humidity sensors. Such outstanding performance makes the sensors suitable for real‐time monitoring applications. [ABSTRACT FROM AUTHOR]

Two‐dimensional covalent organic frameworks (COFs) have emerged as promising materials for energy storage applications exhibiting enhanced electrochemical performance. While most of the reported organic cathode materials for zinc‐ion batteries use carbonyl groups as electrochemically‐active sites, their high hydrophilicity in aqueous electrolytes represents a critical drawback. Herein, we report a novel and structurally robust olefin‐linked COF‐TMT‐BT synthesized via the aldol condensation between 2,4,6‐trimethyl‐1,3,5‐triazine (TMT) and 4,4′‐(benzothiadiazole‐4,7‐diyl)dibenzaldehyde (BT), where benzothiadiazole units are explored as novel electrochemically‐active groups. Our COF‐TMT‐BT exhibits an outstanding Zn2+ storage capability, delivering a state‐of‐the‐art capacity of 283.5 mAh g−1 at 0.1 A g−1. Computational and experimental analyses reveal that the charge‐storage mechanism in COF‐TMT‐BT electrodes is based on the supramolecularly engineered and reversible Zn2+ coordination by the benzothiadiazole units. [ABSTRACT FROM AUTHOR]

Two‐dimensional covalent organic frameworks (COFs) have emerged as promising materials for energy storage applications exhibiting enhanced electrochemical performance. While most of the reported organic cathode materials for zinc‐ion batteries use carbonyl groups as electrochemically‐active sites, their high hydrophilicity in aqueous electrolytes represents a critical drawback. Herein, we report a novel and structurally robust olefin‐linked COF‐TMT‐BT synthesized via the aldol condensation between 2,4,6‐trimethyl‐1,3,5‐triazine (TMT) and 4,4′‐(benzothiadiazole‐4,7‐diyl)dibenzaldehyde (BT), where benzothiadiazole units are explored as novel electrochemically‐active groups. Our COF‐TMT‐BT exhibits an outstanding Zn2+ storage capability, delivering a state‐of‐the‐art capacity of 283.5 mAh g−1 at 0.1 A g−1. Computational and experimental analyses reveal that the charge‐storage mechanism in COF‐TMT‐BT electrodes is based on the supramolecularly engineered and reversible Zn2+ coordination by the benzothiadiazole units. [ABSTRACT FROM AUTHOR]

Rechargeable aqueous zinc-ion hybrid supercapacitors (Zn-HSCs) are promising candidates as large-scale energy storage devices owing to their high electrochemical performance, safety, long life, and low price. The development of nanostructured electrode materials featuring multiple active sites capable of interacting with Zn ions represents an efficient strategy to boost their electrochemical performance. In this work, we report for the first time the use of donor–acceptor carbon-linked conjugated polymers (DA-CCPs) as cathodes in aqueous Zn-HSCs. We have synthesized two novel DA-CCPs via Knoevenagel polymerization between electron-accepting 2,2′,2′′-(benzene-1,3,5-triyl)triacetonitrile and electron-donating 2,5-thiophene dicarboxaldehyde or [2,2′-bithiophene]-5,5′-dicarboxaldehyde, yielding DA-CCP-1 and DA-CCP-2, respectively. DA-CCP-2, which possesses an extra-thiophene unit in the backbone, exhibits improved electrochemical characteristics when compared to DA-CCP-1, and performance surpassing those of other reported cathode materials for aqueous Zn2+ energy storage systems. DA-CCP-1 and -2 based electrodes exhibited an outstanding energy density of 80.6 and 196.3 W h kg−1 respectively, representing the highest value ever reached for conjugated polymers to date. This study not only offers new perspectives for the rational design and precise synthesis of DA-CCPs but it also broadens the choice of cathodes for high-performance aqueous Zn-HSCs. [ABSTRACT FROM AUTHOR]

Tunable physicochemical properties combined with the high chemical and thermal stabilities of covalent organic frameworks (COFs) make them ideal candidates for the next generation of energy storage systems. The integration of redox-active moieties (e.g., thiols) in COFs imparts them a pseudocapacitive characteristic and represents an efficient strategy to boost their performance as electrochemical supercapacitors (SCs). We report the synthesis of two thiol-decorated COFs (SH-COF-1 and SH-COF-2) via the condensation between 2,5-diaminobenzene-1,4-dithiol (DABDT) and benzene-1,3,5-tricarboxaldehyde (TBA), or 1,2,4,5-tetrakis-(4-formylphenyl)benzene (TFPB), respectively. SH-COF-1, which possesses a higher number of thiol groups per structural repeat unit compared to SH-COF-2, exhibits a higher surface area (227 m2 g−1) and enhanced electrochemical performance (areal capacitance of 118 mF cm−2 and a capacitance retention >95% after 1000 cycles), being superior to previously reported COFs missing redox-active units in their scaffolds. Moreover, to demonstrate the multifunctionality resulting from the presence of thiol groups, AuNPs were in situ grown using SH-COFs as templates. By taking advantage of the strength of the bonding between the AuNPs and the SH-COFs, Au-SH-COF hybrids were used as heterogeneous catalysts for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP), showing an excellent catalytic activity kobs, of 1.01 min−1 and 0.71 min−1 for Au-SH-COF-1 and Au-SH-COF-2, respectively, and long-term performance (4-NP to 4-AP conversion above 95% after 10 catalytic cycles). This work highlights the importance of COFs' molecular design towards the development of highly efficient (multi)functional materials. [ABSTRACT FROM AUTHOR]

We report a fast and ultrasensitive colorimetric method for the detection of transition metal ions (Fe3+, Cu2+, Ni2+) in a mixture of toluene–acetonitrile using Schiff base functionalized gold nanoparticles. We achieved limits of detection for the three metal ions at least two orders of magnitude lower than the EU recommended limits. Finally, our methodology was assessed for the determination of nickel in the organic waste of a relevant industrial reaction. [ABSTRACT FROM AUTHOR]

The monitoring of K+ in saliva, blood, urine, or sweat represents a future powerful alternative diagnostic tool to prevent various diseases. However, several K+ sensors are unable to meet the requirements for the development of point‐of‐care (POC) sensors. To tackle this grand‐challenge, the fabrication of chemiresistors (CRs) based on 3D networks of Au nanoparticles covalently bridged by ad‐hoc supramolecular receptors for K+, namely dithiomethylene dibenzo‐18‐crown‐6 ether is reported here. A multi‐technique characterization allows optimizing a new protocol for fabricating high‐performing CRs for real‐time monitoring of K+ in complex aqueous environments. The sensor shows exceptional figures of merit: i) linear sensitivity in the 10–3 to 10–6m concentration range; ii) high selectivity to K+ in presence of interfering cations (Na+, Ca2+, and Mg2+); iii) high shelf‐life stability (>45 days); iv) reversibility of K+ binding and release; v) successful device integration into microfluidic systems for real‐time monitoring; vi) fast response and recovery times (<18 s), and v) K+ detection in artificial saliva. All these characteristics make the supramolecular CRs a potential tool for future applications as POC devices, especially for health monitoring where the determination of K+ in saliva is pivotal for the early diagnosis of diseases. [ABSTRACT FROM AUTHOR]

Noble metal nanoparticles (NPs) are ideal scaffolds for the fabrication of sensing devices because of their high surface-to-volume ratio combined with their unique optical and electrical properties which are extremely sensitive to changes in the environment. Such characteristics guarantee high sensitivity in sensing processes. Metal NPs can be decorated with ad hoc molecular building blocks which can act as receptors of specific analytes. By pursuing this strategy, and by taking full advantage of the specificity of supramolecular recognition events, highly selective sensing devices can be fabricated. Besides, noble metal NPs can also be a pivotal element for the fabrication of chemical nose/tongue sensors to target complex mixtures of analytes. This review highlights the most enlightening strategies developed during the last decade, towards the fabrication of chemical sensors with either optical or electrical readout combining high sensitivity and selectivity, along with fast response and full reversibility, with special attention to approaches that enable efficient environmental and health monitoring. [ABSTRACT FROM AUTHOR]

A simple procedure to obtain highly porous hydrophilic palladium nanodendrites in one-step is described. The synthetic strategy is based on the thermal reduction of a Pd precursor in the presence of a positively charged polyelectrolyte such as polyethylenimine (PEI). Advanced electron microscopy techniques combined with X-ray diffraction (XRD), thermogravimetry and BET analysis demonstrate the polycrystalline nature of the nanodendrites as well as their high porosity and active surface area, facilitating a better understanding of their unique morphology. Besides, catalytic studies performed using Raman scattering and UV-Vis spectroscopies revealed that the nanodendrites exhibit a superior performance as recyclable catalysts towards hydrogenation reaction compared to other noble metal nanoparticles. [ABSTRACT FROM AUTHOR]

We present here a simple procedure for the surface modification of plasmonic nanoparticles (NPs) with a cationic water‐soluble ammonium pillar[5]arene (AP[5]A) in order to create selective surface‐enhanced Raman scattering (SERS) spectroscopy based sensors. The strategy is based on a ligand exchange reaction between the AP[5]A and the stabilizing agent of the as‐prepared plasmonic NPs. The approach could be applied to plasmonic nanoparticles either negatively charged, stabilized by citrate ions (Au spheres) or positively charged, stabilized by cetyltrimethylammonium bromide (Au and Au@Ag nanorods). The SERS performance of all systems was studied as a function of NP size and excitation laser line by using an analyte with no affinity towards the metal surface such as pyrene. The analytical enhancement factor (AEF) for the different systems was estimated between 0.55×104 and 1.49×105. Finally the synergistic effect of combining supramolecular chemistry and plasmonic NPs is demonstrated through SERS‐based detection, in aqueous media, of molecules with no affinity towards a bare plasmonic substrate such as the contaminant pyrene or the biomolecule pyocyanin with nanomolar limit of detection. [ABSTRACT FROM AUTHOR]

Bacterial quorum sensing systems regulate the production of an ample variety of bioactive extracellular compounds that are involved in interspecies microbial interactions and in the interplay between the microbes and their hosts. The development of new approaches for enabling chemical detection of such cellular activities is important in order to gain new insight into their function and biological significance. In recent years, surface-enhanced Raman scattering (SERS) spectroscopy has emerged as an ultrasensitive analytical tool employing rationally designed plasmonic nanostructured substrates. This review highlights recent advances of SERS spectroscopy for label-free detection and imaging of quorum sensing-regulated processes in the human opportunistic pathogen Pseudomonas aeruginosa. We also briefly describe the challenges and limitations of the technique and conclude with a summary of future prospects for the field. [ABSTRACT FROM AUTHOR]

In this minireview, we summarize current research dealing with the combination of noble-metal nanoparticles and different families of supramolecular macrocycles (cyclodextrins, cucurbit[ n]urils, calixarenes, and pillar[ n]arenes). We intended to select relevant publications on the synthesis of noble-metal nanoparticles with macrocycles acting as capping agents or/and reducing agents, as well as on the post-synthetic metal-nanoparticle modification with macrocycles. We also discuss strategies in which supramolecular chemistry is applied to direct the self-assembly of nanoparticles and formation of polymer composites. We finally describe the main applications of these materials in various fields. [ABSTRACT FROM AUTHOR]

We present a simple procedure for the synthesis of quasi-spherical Au nanoparticles in a wide size range mediated by macrocyclic host molecules, ammonium pillar[5]arene (AP[5]A). The strategy is based on a seeded growth process in which the water-soluble pillar[5]arene undergoes complexation of the Au salt through the ammonium groups, thereby avoiding Au nucleation, while acting as a stabilizer. The presence of the pillar[5]arene onto the Au nanoparticle particle surface is demonstrated by surface-enhanced Raman scattering (SERS) spectroscopy, and the most probable conformation of the molecule when adsorbed on the Au nanoparticles surface is suggested on the basis of theoretical calculations. In addition, we analyze the host-guest interactions of the AP[5]A with 2-naphthoic acid (2NA) by using 1H NMR spectroscopy and the results are compared with theoretical calculations. Finally, the promising synergetic effects of combining supramolecular chemistry and metal nanoparticles are demonstrated through SERS detection in water of 2NA and a polycyclic aromatic hydrocarbon, pyrene (PYR). [ABSTRACT FROM AUTHOR]

Chemiresistors: Harnessing Selectivity and Sensitivity in Ion Sensing via Supramolecular Recognition: A 3D Hybrid Gold Nanoparticle Network Chemiresistor (Adv. Funct. Chemiresistors, metal nanoparticles, microfluidics, molecular recognition, point-of-care sensor Keywords: chemiresistors; metal nanoparticles; microfluidics; molecular recognition; point-of-care sensor EN chemiresistors metal nanoparticles microfluidics molecular recognition point-of-care sensor 1 1 1 03/05/21 20210303 NES 210303 In article number 2008554, Davide Bonifazi, Stefano Casalini, Paolo Samorì, and co-workers devise chemiresistors (CRs) based on 3D networks of Au nano- particles (AuNPs) covalently bridged by crown ether-derivative supramolecular receptors for highly selective K SP + sp sensing. [Extracted from the article]

Graphene is regarded as the ultimate material for future flexible, high‐performance, and wearable electronics. Herein, a novel, robust, all‐green, highly reliable (yield ≥ 99%), and upscalable technology is reported for wearable applications comprising reduced graphene oxide (rGO) as the electroactive component in liquid‐gated transistors (LGTs). rGO is a formidable material for future flexible and wearable applications due to its easy processability, excellent surface reactivity, and large‐area coverage. A novel protocol is established toward the high‐yield fabrication of flexible rGO LGTs combining high robustness (>1.5 h of continuous operation) with state‐of‐the‐art performances, being similar to those of their rigid counterparts operated under liquid gating, including field‐effect mobility of ≈10−1 cm2 V−1 s−1 and transconductance of ≈25 µS. Permeable membranes have been proven crucial to operate flexible LGTs under mechanical stress with reduced amounts of solution (<20 µL). Our rGO LGTs are operated in artificial sweat exploiting two different layouts based on lateral‐flow paper fluidics. These approaches pave the road toward future real‐time tracking of perspiration via a simple and cost‐effective approach. The reported findings contribute to the robust and scalable production of novel graphene‐based flexible devices, whose features fulfill the requirements of wearable electronics. [ABSTRACT FROM AUTHOR]