Imine-linked covalent organic frameworks (COFs) are promising metal-free photocatalysts for overall water splitting (OWS), but their practical use is limited by protonation-initiated hydrolysis at the imine linkage. Here, we use first-principles calculations to examine whether post-synthetic imine-linkage cyclization can reduce the susceptibility of the linkage to proton attack while retaining favorable photocatalytic function. Using the triazine-imine-triazine (TIT) COF as a model, we construct four cyclized derivatives with X = NH, O, S, and Se. Cyclization lowers the proton adsorption affinity at the linkage by ∼0.6 eV and shifts the thermodynamically preferred hydrogen evolution reaction (HER) site from the imine nitrogen to the triazine unit, making the hydrolysis-prone linkage less involved in proton-coupled reduction. The cyclized frameworks also show stronger interfragment polarization, reduced exciton binding energy, and more delocalized excited-state carriers. Electrons accumulate on the 2,4,6-tris(4-formylphenyl)-1,3,5-triazine (TFPT)-derived triazine unit, whereas holes localize mainly on the 2,4,6-tris(4-aminophenyl)-1,3,5-triazine (TAPT)-derived phenyl ring, shifting the reduction and oxidation propensities to different parts of the framework. Among the series, TIT-NH gives the highest predicted solar-to-hydrogen (STH) efficiency of 2.4%, compared with 2.2% for the TIT COF. These results identify imine-linkage cyclization as a computationally supported strategy for improving hydrolytic robustness while preserving, and in TIT-NH slightly improving, the photocatalytic water splitting performance in imine-based COFs.

Herein, MXene/Co3O4 layered membranes with peroxymonosulfate (PMS) activation performance were fabricated by embedding porous Co3O4 nanobelt (NB) into MXene nanosheets for dyes removal. The physiochemical properties of membranes were characterized using XRD, SEM, TEM, EDS, ATR-FTIR, XPS, zeta potential measurements, contact angle measurements and ESR techniques. The Co3O4 NB not only regulates interlayer channels, but also acts as catalysts for the degradation of small molecule organic pollutants via PMS activation. The resulting layered membrane shows enhanced dye removal performance, attributed to the regulated dspacing and newly endowed excellent PMS activation performance. The separation efficiencies of MXene/Co3O4 layered membrane for dyes are over 97.5 %, the permeabilities are over 473 L m-2h-1 bar-1, and the permeability is about 2.5 times that of neat MXene membrane. Moreover, the established dynamic degradation system demonstrated a remarkable small molecular dye (e.g. Methylene blue) removal efficiency nearly 100 %, emphasizing its applicability and potential in practical applications. Additionally, the separation and catalytic degradation mechanisms of MXene/Co3O4 layered membrane for dyes were verified and analyzed through related tests and characterizations. This work provides a new dual-regulation strategy of d-spacing and catalytic performance to enhance the removal ability of layered membranes for different organic pollutants in wastewater.

Photocatalytic H2O2 production from H2O and O2 provides a sustainable alternative to the energy-intensive, multistep anthraquinone (AQ) process that relies on metal catalysts (e.g., Pd/Ni). Although many photocatalysts have been explored, achieving high efficiency under sacrificial-agent-free conditions with a rationally defined active site remains challenging. Here, we report an inverse-design strategy for covalent organic frameworks (COFs) based on "boat-like C═N-conjugated fragments" (-C═N-C═N- or -N═C-C═N-) which mimic key AQ reactivity by integrating active molecular fragments into periodic frameworks through a bottom-up approach. First-principles calculations identified 39 molecular fragments, including 36 newly proposed structures, and demonstrated their ability to drive the two-electron oxygen reduction reaction via sequential protonation and electron transfer. Unlike conventional single-property descriptors (e.g., band gap), we introduce a holistic electronic activity descriptor based on density-of-states (DOS) similarity to screen 106 designed COFs. This electronic fingerprint identified 11 candidates with >70% total DOS and >60% carbon partial DOS similarity relative to a high-performance reference. Subsequent Gibbs free-energy analyses predict that 9 candidates can support sacrificial-agent-free H2O2 production under visible light, corresponding to a theoretical screening success rate of approximately 81%. Experimental validation included the synthesis of TRI-BIP-TRI (TBiT) via trifluoromethanesulfonic acid-catalyzed cyclotrimerization. Under visible light (>400 nm) in pure water under O2, TBiT produces H2O2 at 3084.27 μmol g-1 h-1 without sacrificial agents. These results establish a computation-guided framework for designing COF photocatalysts for sustainable H2O2 production.

Introduction:1-methylcyclopropene (1-MCP) and hydrogen sulfide (H2S) play important roles in the ripening and senescence of postharvest fruits and vegetables. However, little knowledge was available for the effect of the combined treatment of 1-MCP and H2S on the quality maintenance of postharvest strawberry fruit. Methods:The synergistic effects of 1.0 μL L-1 1-MCP and 0.8 mmol L-1 sodium hydrosulfide (NaHS, H2S donor) combined treatment on the sugar and energy metabolisms of strawberry fruit during cold storage at 4 ± 0.5°C with a relative humidity of 80-85% for 15 d were studied. Results:The results showed that the combined treatment effectively suppressed the increase of decay rate, decay index, and weight loss rate while maintaining the firmness and visual quality of strawberry fruit compared to the 1-MCP or H2S treatment. Moreover, the combined treatment maintained higher sucrose content and lower contents of glucose and fructose by inhibiting the activities of acid invertase (AI) and neutral invertase (NI), while enhancing the activities of sucrose synthase (SS) and sucrose phosphate synthase (SPS). Meanwhile, strawberry fruit treated with the combination elevated ATP levels and energy charge by upregulating key enzymes in energy metabolism, including succinate dehydrogenase (SDH), cytochrome c oxidase (CCO), H+-adenosine triphosphatase (ATPase) and Ca2+-ATPase. Conclusion:These results indicated that 1-MCP and H₂S acted synergistically to regulate sugar catabolism and energy homeostasis, promoting elevated sucrose accumulation and mitochondrial energy production, thereby maintaining the integrity of cell structure and the quality of strawberry fruit.

Covalent organic frameworks (COFs) are a kind of promising electrochemiluminescence (ECL) crystalline nanoemitters due to their rapid intrareticular charge transfer and predesigned structures. However, the high polarization of heteroatom-containing linkages impedes the charge transfer within reticular structures. In this study, we construct a series of halogenated COFs nanoemitters composed of terephthalaldehyde ortho-substitutions and 1,3,6,8-tetrakis(4-aminophenyl)pyrene ligands via a covalent halogenation predesign strategy. The incorporation of covalently bonded halogen atoms promotes a dense electron population in carbon–carbon antibonding molecular orbitals, thereby facilitating efficient p–π conjugation within the COF structure. Based on the improved intrareticular charge transfer along carbon skeleton, as evidenced by the Hall effect and terahertz spectroscopy, the brominated COF demonstrates a 49-fold enhancement in ECL intensity compared to nonhalogenated COF. Furthermore, the performance of four partially brominated COFs establishes a positive correlation between the degree of Br doping and ECL intensity. Beyond the corresponding model compounds, the conjugated frameworks of COFs significantly amplify the halogenation-induced enhancement effect. This halogenation-promoted p–π conjugation in reticular skeleton provides a universal strategy to sensitize crystalline nanoemitters for decoding ECL enhancement mechanism.

Nanofiltration membranes are nowadays widely being used for dye wastewater treatment. However, these membranes often undergo significant and undesirable fouling during wastewater treatment. Herein, a Co3O4/PES composite nanofiltration membrane with...

Solar-driven photoelectrochemical (PEC) synthesis emerges as a promising pathway to produce hydrogen peroxide (H2O2), reimagining the energy-intensive anthraquinone method. However, scaling PEC systems from laboratory-scale prototypes to practical large-area installations remains a significant scientific and engineering challenge, primarily due to limited catalytic selectivity at photoelectrode surfaces and rapid performance degradation during upscaling. This study presents a modular, bias-free PEC system designed for scalable solar-driven H2O2 production. Conjugated polycarbazole frameworks (CPFs) containing rationally designed diacetylene and anthraquinone moieties functions as molecularly precise catalytic layers, enabling concurrent two-electron pathways at both the photoanode and photocathode. The resulting photoanode and photocathode deliver faradaic efficiencies of 94.08% and 95.50%, respectively, for H2O2 production. Integrating these photoelectrodes into a 1 cm2 unbiased tandem PEC device achieves a solar-to-chemical conversion (SCC) efficiency of 2.11%. More importantly, scaling these devices to a 1 m2 membrane-free PEC panel reactor via a modular assembly strategy yields an average SCC efficiency of 1.10% under natural sunlight, representing the largest reported solar-driven PEC system for H2O2 production to date. This study bridges the gap between laboratory-scale experimentation and real-world applications, providing a scalable framework for decentralized, solar-driven H2O2 production.

Stimulated anionic redox reactions are commonly utilized to design layered oxide cathodes for high-energy sodium-ion batteries (SIBs). Unfortunately, excessive oxygen redox often causes irreversible lattice oxygen loss and cation migration, leading to rapid capacity and voltage fading, as well as slow reaction kinetics. Here, we design and synthesize a P2/O3 biphasic cathode material, Na0.8Ni0.3Mn0.5Cu0.1Ti0.1O2 (NNMCT), which can activate the redox of oxygen at significantly lower voltage while leveraging the high stability of the P2 phase and the high capacity of the O3 phase. Furthermore, we elucidate the reductive coupling mechanism (RCM) of the uncommon electron transfer from oxygen to Ni/Mn ions within the material, which enhances the reversibility of the anion redox reaction, and induces the formation of strong covalent Ni/Mn-(O-O) bonds that effectively inhibit excessive oxygen oxidation and avoid rapid capacity decay. As a result, NNMCT cathode materials exhibit excellent reversible capacity (134.0 mAh g-1 at 10 mA g-1) and superior long-cycle stability (85.2% capacity retention after 500 cycles at 100 mA g-1). The intrinsic functional mechanism of RCM is fully elucidated through a series of in situ/ex situ characterizations as well as theoretical calculations. These findings underscore the advantages of biphasic/multiphasic cathodes for high-energy SIBs.

MXene membranes have garnered substantial research interest for molecular/ion separation and transport applications, primarily attributed to their distinctive atomic-scale thickness and precisely ordered nanochannel architectures. Nevertheless, the low permeability of MXene membrane poses significant obstacles to their broad adoption. In this study, an electrostatically repulsion-adjusted self-cleaning composite membrane (BiOCl/CNF/ MXene) was fabricated through vacuum filtration-assisted self-assembly, employing MXene, BiOCl, and cellulose nanofibers (CNF) as assembly units. The high electronegativity of BiOCl nanosheets and CNF results in the negatively charged MXene nanosheets being oriented through electrostatic repulsion of membrane components, within the membrane components, resulting in their organized arrangement, thereby forming relatively flat nanochannels between layers. The fabricated membrane demonstrates a superior flux of 310.0 L m- 2 h- 1 and excellent rejection for various dyes (98.9 % for congo red, 97.2 % for methyl blue, 99.6 % for rhodamine B, and 99.7 % for crystal violet). Additionally, the membrane maintains high dye rejection and permeability across different pH conditions (i.e., pH = 3, 7, and 11) and different dye concentrations (i.e., 50 ppm and 250 ppm). Furthermore, the membrane exhibits good stability under cross-flow separation conditions and robust antifouling performance under visible light with a flux recovery ratio of up to 95.4 %. The electrostatic repulsion regulation channel coupling catalytic technology proposed in this paper provides valuable insights for solving the membrane fouling problem and for manufacturing high-performance MXene-based membranes for efficient dye wastewater treatment.

Colloidal quantum dots (QDs) are attractive gain materials owing to the wide range of accessible colors. However, the existing QD lasers struggle to combine technologically relevant metrics of low threshold and long operating duration with considerable output powers. Here a new class of full-color QD lasers are reported, featuring low threshold, uninterrupted operation for dozens of hours, and multimilliwatt output under quasi-steady-state pumping, by coupling the high-gain QDs with a double-clad pumping scheme. Corroborated by the comprehensive transient spectroscopy and numerical simulation, it is demonstrated that the ternary QDs with specially designed fine nanostructure enable the low gain threshold, giant gain coefficient, long gain lifetime, and excellent resistance against intense photoexcitation. Meanwhile, the double-clad QD-fiber design allows for record-long light-gain interaction, high conversion efficiency, and sustained device operation. As such, the QD lasers with multimilliwatt output powers, unobserved in QD lasers to date, have been realized. Further, the proof-of-concept application for generating vortex beams with various topological charges is demonstrated. This work represents significant progress toward practical lasers based on QDs.

Covalent organic frameworks (COFs) offer a compelling platform for the efficient photosynthesis of hydrogen peroxide (H2O2). Constructed with diverse topologies from various molecular building units, COFs can exhibit unique photocatalytic properties. In this study, three π-conjugated 2D sp2 carbon-linked COFs with distinctly different topologies (hcb, sql, and hxl) are designed to investigate the topological effect on the overall photosynthesis of H2O2 from water and oxygen. Despite their similar chemical and band structures, the QP-HPTP-COF with hxl topology outperformed other COFs in the photosynthesis of H2O2, demonstrating a remarkable solar-to-chemical conversion efficiency of 1.41%. Comprehensive characterizations confirmed that the hxl topology can substantially improve charge separation and transfer, thereby significantly enhancing photocatalytic performance. This study not only unravels the topology-directed charge carrier dynamics in COFs but also establishes a molecular engineering framework for developing high-performance photocatalysts for sustainable H2O2 production.

Utilizing sunlight to split water into H2 and O2 is a highly promising approach in renewable energy production approaches. Recently, significant efforts have been devoted to developing innovative photocatalysts for splitting water. Metal-free two-dimensional (2D) covalent organic frameworks (COFs) are emerging as ideal catalytic platforms for this purpose. However, the rational design of these materials requires appropriate band alignment and active sites capable of catalyzing both hydrogen and oxygen evolution reactions (OERs), which depends on the judicious selection of molecular precursors. To address these requirements, first-principles calculations have proven to be an efficient method for designing and screening potential photocatalysts. Here, we provide a concise overview of recent advancements in the development of 2D COFs photocatalysts for overall water splitting (OWS), examining it from a theoretical perspective. This includes outlining the design principles, exploring the data-driven discovery of potential candidates using a COFs database, and applying machine learning (ML) techniques to predict the electronic structure of COFs based on the molecular orbitals of their precursors. Furthermore, we discuss the accuracy of current computational methods and address future challenges and potential of 2D COFs in practical applications for OWS.© 2017 Elsevier Inc. All rights reserved.

Facile preparation of hydrophilic membranes is essential for achieving efficient separation of oil-water emulsion. In this paper, a hydrophilic PVDF@TP membrane was prepared by very simple direct modification using green tea (The main extract is tea polyphenols, TP). The PVDF@TP membrane exhibits good hydrophobicity in air and underwater superoleophilicity. The oil-water separation potential of this membrane was studied using several model oil-in-water emulsions. The resulting membrane exhibitd high separation efficiency (above 99 %) and separation fluxes (955-1672 L m(2) h(-1) bar(-1)) for various oil-in-water emulsions. Additionally, separation efficiency of PVDF@TP membrane was still above 98 % even after 10 times continuous separation, demonstrating its good antifouling ability and stability. In addition, bending, ultrasonic and stirring treatments showed that the membrane has good mechanical durability. In view of the advantages of facile preparation, economy and high-performance, the hydrophilic PVDF@TP membrane has a very broad application potential in industrial oily wastewater and oil spill treatment.

The flocculating ability of the flocculant directly affects the quality of the treated water. Poly-ferric sulfate flocculant (PFS) is a commonly used flocculant. The purpose of this study is to use the electrodialysis process to concentrate the solution and the bipolar membrane electrodialysis to dissociate water to produce acid and alkali to achieve the preparation of poly-ferric sulfate flocculant. The effects of current density, feed flow rate, and sulfuric acid addition on the quality of PFS were tested. Experiments have proved that the increase of current density is beneficial to the increase of PFS alkalinity and turbidity removal rate, and at the same time energy consumption will be reduced. When the current density is 30 mA/cm2, the alkalinity reaches a maximum of 21.04% and the energy consumption is 1.52 kW & BULL;h (kg H2SO4). When the current density is 20 mA/ cm2, the turbidity removal rate reaches a maximum of 94.23% and the energy consumption is 2.46 kW & BULL;h (kg H2SO4). In addition, the solid PFS was subjected to scanning electron microscopy, X-ray diffraction and Fourier-transform infrared spectroscopy tests after vacuum drying to further confirm the structure of the PFS.

A quantum dot-sensitized solar cell (QDSSC) is a promising next-generation photovoltaic technology due to its clean, low cost, high efficiency, and easy fabrication. To date, various transition-metal sulfides (TMSs) have been demonstrated, yet the utilization of bimetallic sulfides has rarely been reported. While the bimetallic TMS has excellent chemical and physical properties, it displayed improved activity and stability as a counter electrode (CE) in QDSSCs with polysulfide electrolytes. In this regard, a simple yet affordable method is developed for manufacturing CEs based on cobalt manganese sulfide (CMS) composites. Herein, cobalt manganese oxyhydroxide was first deposited on the fluorine tin oxide substrate by a single-step redox process and then sulfurized to CMS. By controlling the precursor ratio of Co and Mn, the bimetallic CMS could be adjusted to manipulate the Sn2- reduction activity. Taking the advantage of those bimetallic systems, their synergistic effects demonstrated superior long-term stability in a different multi-cyclic voltammetry treatment than conventional CuS CEs. Notably, the QDSSCs with optimized CMS CEs also exhibited a high solar-to-electricity conversion efficiency (eta) of 5.88 +/- 0.19% under 100 mW cm-2 irradiation, indicating that CMS CE exhibited superior reduction activity to Sn2-.

Understanding the levels change in biomarkers over time, especially glucose, is crucial for diabetics to inform early therapy. Recently, wearable sweat biosensors which operate in a non-invasive way have raised attention, providing continuous monitoring of the severity level. Nevertheless, the key challenges are that multiplexed motions may result in undesirable metal cracking by the rigid electrocatalytic layer, leading to decreased sensitivity and stability. In this work, we designed an N-GQDs anchored PANI matrix to realize flexible wearable biosensors with high detection accuracy. Upon the enhanced electron transfer by N-GQDs, N-GQDs/PANI nanocomposite offers greater sensitivity in H2O2 detection compared to pristine PANI, resulting in a sensitivity of 68.1 +/- 1.11 and 44.06 +/- 2.1 mu A mM-1 cm-2, respectively. Moreover, after the glucose oxidase (GOx) immo-bilization, GOx/N-GQDs/PANI-based biosensors had shown excellent performance for glucose detection in artificial sweat. Precise glucose detection was also maintained after integrating into a flexible electrode, the sensitivity of the GOx/N-GQDs/PANI-based biosensor had retained 93.2 % with no apparent cracks in the morphology of the nanocomposite layer, compared to GOx/Pt-based one (71.3 %) toward glucose detection after a continuous bending test. Thus, the N-GQDs/PANI nanocomposite layer can provide reliable long-term moni-toring with robust electrodes for non-invasive human sweat glucose monitoring on a wearable biosensor.

Covalent organic frameworks (COFs) are highly desirable for achieving high-efficiency overall photosynthesis of hydrogen peroxide (H2O2) via molecular design. However, precise construction of COFs toward overall photosynthetic H2O2 remains a great challenge. Herein, we report the crystalline s-heptazine-based COFs (HEP-TAPT-COF and HEP-TAPB-COF) with separated redox centers for efficient H2O2 production from O-2 and pure water. The spatially and orderly separated active sites in HEP-COFs can efficiently promote charge separation and enhance photocatalytic H2O2 production. Compared with HEP-TAPB-COF, HEP-TAPT-COF exhibits higher H2O2 production efficiency for integrating dual O-2 reduction active centers of s-heptazine and triazine moieties. Accordingly, HEP-TAPT-COF bearing dual O-2 reduction centers exhibits a remarkable solar-to-chemical energy efficiency of 0.65 % with a high apparent quantum efficiency of 15.35 % at 420 nm, surpassing previously reported COF-based photocatalysts.

Covalent organic frameworks (COFs) hold great promise for solar‐driven hydrogen production. However, metal‐free COFs for photocatalytic overall water splitting remain elusive, primarily due to challenges in simultaneously regulating their band structures and catalytic sites to enable concurrent half‐reactions. Herein, two types of π‐conjugated COFs containing the same donor–acceptor structure are constructed via Knoevenagel condensation and Schiff base reaction to afford cyanovinylene‐ and imine‐bridged COFs, respectively. The difference in the linkage leads to a remarkable difference in their photocatalytic activity toward water splitting. The 2D sp 2 carbon‐linked COF exhibits notable activity for photocatalytic overall water splitting, which can reach an apparent quantum efficiency of 2.53% at 420 nm. In contrast, the 2D imine‐linked COF cannot catalyze the overall water‐splitting reaction. Mechanistic investigations reveal that the cyanovinylene linkage is essential in modulating the band structure and promoting charge separation in COFs, thereby enabling overall water splitting. Moreover, it is further shown that crystallinity substantially impacts the photocatalytic performance of COFs. This study represents the first successful example of developing metal‐free COFs with high crystallinity for photocatalytic overall water splitting.

Addressing energy and environmental issues, developing highly efficient, durable, and earth-abundant, electrocatalysts are crucial in oxygen evolution reaction (OER) for energy conversion and storage. Extensive research about the metal-organic framework (MOF) derived layered double hydroxides (LDH) and carbon-based electrocatalysts have been devoted, despite the exceptional performance in OER, yet the limited exposed active sites remain a challenge. Therefore, we reported a novel heteroatom-doped graphene quantum dots (GQDs) incorporated into MOF-derived NiFe-LDH. Taking advantage of abundant active and edge sites of GQDs and modifying the surface chemistry by chemical doping with foreign atoms, the designed heteroatom-doped GQDs/MOFderived LDH exhibited superior catalytic performance low overpotential of 251 mV at a current density of 100 mA cm-2 in alkaline media. Our result confirmed the synergistic effect between the doped heteroatom and the uttermost exposure of heteroatom-doped GQDs/MOF-derived LDH's active sites on its surface, providing swift reactant's transportation and adequate contact for improving the OER performance.

Here, a robust antifouling NH2-MIL-88B coated quartz fibrous membrane (NM88B@QFM) was developed for efficient oil-water emulsion separation via a one-step solvothermal method. The effects of NM88B precursor concentration on the morphology and surface wettability of the membranes were investigated. The prepared NM88B@QFM showed good photo-Fenton self-cleaning ability and superhydrophilicity/underwater superoleophobicity with water contact angle and underwater oil contact angle of 0 degrees and 161.3 degrees, respectively. The NM88B@QFM exhibited high separation efficiencies and high permeation fluxes (up to 99.4% and above 350 L m(-2) h(-1), respectively for a series of surfactant-stabilized oil-in-water emulsions under solely gravity-driven separation. Moreover, the NM88B@QFM showed good antifouling self-cleaning ability because Fenton-like catalytic NM88B can degrade the foulant on the membrane surface, enabling it to maintain its performance over many separation cycles. In view of the advantages of NM88B@QFM such as high separation efficiency, excellent self-cleaning and gravity self-driven performance, this type of membrane appears to be a promising candidate for low energy input, long-lasting oil-water separation.