Nickel Metal-Organic Frameworks (MOFs) Ni-BDC (BDC: 1,4-benzenedicarboxylic acid) with coordination-unsaturated metal sites (CUMs) exhibits remarkable CO2 reduction activity under visible-light irradiation. However, its photocatalytic mechanism remains a challenging due to complex charge-transfer pathways. Herein, a series of CUMs-tunable MOFs (Ni-BDC-Dx) were synthesized via a pyrazine-assisted aqueous-phase strategy for photocatalytic CO2 reduction. A positive correlation is found between the CUMs density and photocatalytic activity, and Ni-BDC-D1.0 with highest CUMs density achieves a remarkable CO production rate of 3503.1 μmol·g-1·h-1, which is 5.2 times higher than conventional bulk Ni-BDC. Experimental and theoretical results reveal that CUMs induce the formation of defect level and enhance CO2 adsorption. The defect level serves as electron trap to promote localized charge accumulation by the optimizing charge transfer pathway. This pathway is achieved by facilitating non-radiative relaxation pathway to inhibit radiative carrier recombination behavior. These findings provide insights into electron transfer mechanism on CUMs-rich Ni-BDC for photocatalytic CO2 reduction.

Simultaneous removal of As(III) and As(V) remains challenging because their distinct aqueous speciation imposes different interfacial interaction requirements, particularly in multicomponent water matrices. Herein, a magnetic mesoporous zirconium oxide-chitosan composite (Fe3O4-ZrO2@CS) was developed as a dual-domain adsorbent for mixed-speciation arsenic removal. The composite exhibited a BET surface area of 150.1 m2 g−1 and was rapidly magnetically separated from water within 2 s. At initial concentrations of 100 μg L−1 for each arsenic species, removal efficiencies of 90.47% for As(III) and 95.76% for As(V) were achieved within 6 min at pH 7.0, identified as the optimum working pH for simultaneous adsorption. The Langmuir maximum adsorption capacities reached 260.8 mg g−1 for As(III) and 186.0 mg g−1 for As(V). Removal efficiencies remained above 80% in the presence of sulfate and above 90% in a mixed-contaminant system containing Cr(VI), Cd(II), Hg(II), and Pb(II). Component-comparison and pH-dependent experiments indicated that hydroxylated Zr-containing domains predominantly promoted coordination interactions with neutral As(OH)3, whereas protonated chitosan amino groups facilitated the electrostatic uptake of anionic arsenate species. Density functional theory (DFT) calculations further supported favorable species-dependent interactions between arsenic and the corresponding functional domains. This study establishes a modular dual-domain interfacial design strategy that couples coordination-active inorganic sites with charged polymeric domains, providing a mechanistic and practical framework for magnetically recoverable treatment of mixed-speciation arsenic contamination without a separate pre-oxidation step.

Blue carbon dots (B-CDs) were prepared via a hydrothermal method using citric acid and urea as precursors, and subsequently employed to construct a carbon dots/MOF-based composite (B-CDs@Cu-MOF) through an in situ one-pot approach. The B-CDs were successfully incorporated into the pores and onto the surfaces of the Cu-MOF, without significantly altering its octahedral crystalline structure, but with a slight decrease in surface area. Due to the reduction nature of the B-CDs, partial reduction of Cu(II) occurred in the synthetic process, resulting in the coexistence of Cu(II) and Cu(I) within the B-CDs@Cu-MOF. The peroxidase (POD)-like catalytic activity of B-CDs@Cu-MOF was investigated systematically using the oxidation of o-phenylenediamine (OPD) in the presence of H2O2. The B-CDs@Cu-MOF exhibits distinctly improved POD-like activity, compared to the original Cu-MOF and other previously reported Cu-based POD mimics. The catalytic kinetics parameters including Michaelis constant (Km) and maximum initial velocity (Vmax) were determined. In addition, these B-CDs@Cu-MOF show fluorescence emission at 450 nm, attributed to the B-CDs. By integrating it with the fluorescence emission at 564 nm from 2,3-diaminophenol (DAP), a product of OPD oxidation, a ratiometric sensing platform was developed. This platform, composed of B-CDs@Cu-MOF, OPD and H2O2, was used to detect L-cysteine (L-Cys). In this system, L-Cys competitively consumes reactive oxygen species (ROS) and inhibit DAP formation. Based on that, a ratiometric fluorescence sensor for L-Cys detection was constructed, exhibiting a linear response range from 10 µmol·L− 1 to 100 µmol·L− 1, and a detection limit of 1.77 µmol·L− 1. This work well integrated the enzyme-like catalysis of Cu-MOF and the fluorescence properties of CDs, that provides an excellent ratiometric sensing platform toward target molecules.

Due to the difficulty of conventional photocatalytic systems in simultaneously achieving strong oxidation and reduction processes, the treatment of wastewater containing coexisting uranium and organic pollutants remains a critical challenge in the field of photocatalysis. Herein, a novel g-C3N4/Bi2MoO6/Bi2WO6 (GBMW) ternary photocatalyst with a dual Z-scheme heterojunction architecture was rationally constructed for the removal of U(VI) and tetracycline (TC) under visible-light irradiation. The dual Z-scheme heterojunction extends the visible-light response range and accelerates interfacial charge transfer, while preserving strong redox potentials. Within 100 min, GBMW achieves a U(VI) reduction efficiency of 91.6% and a TC degradation efficiency of 97.6%, with corresponding kobs values of 0.02332 and 0.03664 min−1, respectively, which are significantly superior to those of BiMO, BiWO, GCN and GBW. Notably, U(VI) can act as an efficient electron acceptor to promote the separation of electrons and holes in GBMW, which significantly facilitates the degradation of TC. Moreover, GBMW demonstrates excellent stability and anti-interference performance in various real water matrices. This work not only provides a feasible strategy for constructing high-efficiency dual Z-scheme heterojunctions photocatalysts, but also offers an effective solution for treating complex wastewater containing coexisting organic pollutants and radioactive contaminants.

A double-shelled hollow iron-encapsulated zeolite (Fe2O3@H-ZSM-5@H-ZSM-5) catalyst was synthesized via a stepwise etching-recrystallization strategy for persulfate activation. The unique double-shelled hollow architecture enhances mass transfer while ensuring ultra-low iron leaching and excellent structural stability, resulting in outstanding reusability.

In recent years, graphitic carbon nitride (g-C3N4) containing nitrogen vacancies has been widely used as a photocatalyst in CO2 reduction reactions. The introduction of transition metals into this system helps to improve its photocatalytic performance, but regulating the synergistic effect of nitrogen vacancies and metal sites has always been a challenge. In this work, we synthesized a composite material featuring metal Co species anchored on g-C3N4 with nitrogen vacancies (Co/Nv-WCN) through the molten salt method combined with the simple chemical reduction method, achieving a sea urchin-like morphology. The experimental results reveal that the concentration of nitrogen vacancies in the composites was successfully controlled by trace H2O during the molten salt synthesis system. The as-prepared Co-10/Nv-WCN-L sample (by trace-H2O-derived) with optimal nitrogen vacancies achieves a CO production rate (252.2 mu mol g(-1) h(-1)), demonstrating one-fold activity as much as that of Co-10/Nv-WCN-M with excessive vacancies (by free-H2O-derived, 132.2 mu mol g(-1) h(-1)), and surpassing the performance of the corresponding reference materials. The excellent photocatalytic activity is attributed to the synergistic effect between the appropriate concentration of nitrogen vacancies and Co species, which is also proved by the photoelectrochemical characterization. This study provides new insights for designing efficient, low-cost, and durable CO2 reduction photocatalysts.

By multi-metal doping method, the morphology of metal-organic frameworks (MOFs) could be regulated, leading to more exposed active sites and enhanced mass transfer for electrolyte, thereby significantly improving the electrocatalytic oxidation capacity of MOFs toward glucose molecules. This strategy offers a novel approach for designing high-performance nickel-based MOF non-enzymatic electrochemical glucose sensors. In this study, a series of bimetallic NiCo-MOFs were successfully synthesized via a one-pot solvothermal method, and the influence of varying metal ratios on sensor performance was systematically investigated. Electrochemical results demonstrate that bimetallic NiCo-MOFs exhibit superior catalytic activity compared with monometallic Ni-MOF. Among bimetallic NiCo-MOFs, NiCo3-MOF (Ni:Co = 1:3) displays the most outstanding sensing performance, achieving high sensitivities of 2048.55 & micro;A center dot mM-1 center dot cm-2 and 966.45 & micro;A center dot mM-1 center dot cm-2 in the linear ranges of 0-600 & micro;M and 600-3000 & micro;M, respectively. The detection limit (LOD, S/N = 3) is as low as 0.57 & micro;M, with a rapid response time of only 1.8 s. In contrast, the monometallic Ni-MOF exhibits significantly lower sensitivities of 584.15 & micro;A center dot mM-1 center dot cm-2 and 414.58 & micro;A center dot mM-1 center dot cm-2 under identical conditions. This enhanced electrochemical performance is attributed to the synergic effect between cobalt and nickel active sites in MOFs and nanosheetlike architecture, resulting in increasing of the specific surface area and exposing more accessible active sites. Furthermore, bimetallic NiCo3-MOF demonstrates excellent current stability over a prolonged period of 3000 s. Selectivity tests confirm its strong resistance to common interfering species such as sodium chloride, potassium chloride, sucrose, lactose, uric acid, dopamine hydrochloride, and ascorbic acid, while reliable detection performance is maintained in bovine serum albumin samples. Therefore, bimetallic NiCo3-MOF holds significant promise for application in MOF-based electrochemical biosensors.

Acid-reagent-engineered tunable multicolor carbon dots via solid-phase pyrolysis.

In this study, a novel nitrogen-doped carbon-based copper nanozyme (Cu-N/C) was constructed via an in situ derivatization of designed copper complexes, which shows excellent laccase-like catalytic activity. In it, a copper complex was synthesized using copper chloride dihydrate and 1,10-phenanthroline as the precursors, and then a controlled pyrolysis strategy was conducted to obtain the nitrogen-doped carbon-based composites with atomically dispersed copper active sites. These isolated copper sites are anchored within the nitrogen-doped carbon framework, providing an effective catalytic center that mimics natural laccase. In the catalytic process, the Cu-N/C nanozyme exhibits better substrate affinity and faster catalytic rates in comparison with other laccase mimics. The catalytic mechanism studies demonstrate that the Cu-N/C nanozyme directly drives the substrate oxidation by using activating oxygen molecules, and the reaction path is similar to that of natural laccase. These Cu-N/C nanozymes maintain satisfactory catalytic activity at high temperatures and across a wide pH range, and can also be used in high-salt environments, thereby overcoming the operation limitations of biological laccase. Based on that, we have developed a smartphone-assisted portable colorimetric sensing platform to achieve a rapid visual detection of phenolic contaminants in the water. More interestingly, these Cu-N/C nanozymes can also efficiently degrade dye contaminants, with a decolorization rate of more than 75% within 40 min. The work highlights a 'coordination-pyrolysis' strategy as an effective way to design a biomimetic nanozyme with tunable active sites, and its stable catalytic performance provides a feasible solution to environmental detection and pollutant degradation.

This study reports the one-step in-situ assembly of a polydopamine (PDA)@ZIF-8 functional layer on polyethersulfone (PES) ultrafiltration (UF) membranes for high-flux, antifouling dye/salt separation. Leveraging the synergistic effect of dopamine (DA) self-polymerization and the in-situ growth of ZIF-8 during the nonsolventinduced phase separation (NIPS) process, a highly integrated PDA@ZIF-8 functional layer was successfully constructed on the PES membrane surface. Strong coordination and chelation interactions among Zn2+ ions, the catechol moieties of PDA, and 2-methylimidazole (2-MIM) increase the casting solution viscosity, triggering delayed demixing and promoting the migration of hydrophilic precursors toward the membrane interface. Structurally, the in-situ assembly of PDA@ZIF-8 significantly increased the selective layer thickness from 4.73 mu m to 33.10 mu m. The resulting ultrafiltration membrane exhibited exceptional separation efficiency, delivering a Congo Red (CR) rejection rate of over 99.5% while maintaining a salt rejection rate under 5%, enabling the efficient fractionation of dyes and salts. A high pure water flux of 455 L center dot m(-2)center dot h(-1) at 0.1 MPa is attained, which is attributed to the enhanced surface hydrophilicity and the intrinsic sub-nanometer microporous channels of ZIF-8. Furthermore, the functionalized layer demonstrates remarkable antifouling properties toward anionic dyes, with a stable flux recovery ratio (FRR) exceeding 85% after multiple cycles of CR filtration. This research presents an effective membrane preparation strategy that enhances separation performance while ensuring excellent longterm antifouling stability.

Molten salt-assisted pyrolysis has emerged as an effective strategy for engineering defective/doped g-C3N4 photocatalysts for CO2 reduction. While K+ incorporation enhances interlayer charge transport, excessive K+ generates detrimental nitrogen vacancies that destabilize the heptazine framework and compromise carrier mobility. Herein, we developed S/K co-doped graphitic carbon nitride (g-C3N4) with tunable nitrogen vacancies (denoted SWCN-M) via molten salt (KCl-LiCl) pyrolysis of sulfur-containing supramolecular precursors (melamine with thiourea or thioacetamide). The nitrogen vacancy concentration is precisely modulated by the choice of sulfur precursor (thiourea vs. thioacetamide) to optimize the synergy effect of K+-N-vacancy, and eventually boosting photocatalytic performance. The thiourea-derived SWCN-MTU achieves a CO evolution rate of 165.7 mu mol g-1h-1, outperforming its thioacetamide analogue (SWCN-MTAA, 90.4 mu mol g-1h-1), pristine WCN (53.8 mu mol g-1h-1), and K-doped WCN-M (64.3 mu mol g-1h-1) by factors of 1.8, 3.1, and 2.6, respectively. DFT calculation results reveal that S-doping induces charge localization, elevating the N-vacancy formation energy via Coulombic repulsion with K+. This work advances the rational design of vacancy-engineered carbon nitride for photocatalytic CO2 reduction.

Metal-COFs, formed by anchoring metal ions onto covalent organic frameworks (COFs), are an emerging class of modified porous materials for enhancing photocatalytic CO2 reduction performance. However, the dispersion and stability of metal species in the COFs framework remains a significant challenge. In this work, an atomically dispersed cobalt (Co)-modified COF (Co@TAPT-DMTA) was synthesized using a bidentate coordination strategy via a one-pot method for photocatalytic CO2 reduction. Co@TAPT-DMTA exhibits highly efficient CO2 reduction performance under visible light illumination. Its CO production rate is 5563.2 μmol·g-1·h-1, which is 32.7-fold higher than that of unmodified TAPT-DMTA (170.2 μmol·g-1·h-1), TAPT-PDA (338.3 μmol·g-1·h-1) and Co@TAPT-PDA (1099.7 μmol·g-1·h-1). Compared with monodentate ligand TAPT-PDA, both experimental and theoretical studies confirm the successful construction of an N,O-bidentate coordination environment within the TAPT-DMTA framework, wherein the resulting N-Co-O structure enables atomic-level dispersion of cobalt species. At the same time, the atomically dispersed Co species regulate the electronic structure of TAPT-DMTA, leading to a narrower band gap of Co@TAPT-DMTA, thereby improving both CO2 selectivity and conversion efficiency. This work provides valuable insights for the design of metal-modified COFs with highly dispersed metal active sites for photocatalytic CO2 reduction.

Rapid, efficient and reliable sensing detection with smartphone assisted RGB model for AA is of great significance. Herein, binary metal (Mn/Ce) oxides were fabricated by using a Mn(II)-doped Ce-MOF as the sacrificial precursor through ordinary pyrolysis at 500 degrees C. The microstructure characteristics, including Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD), and X-ray Photoelectron Spectroscopy (XPS) were employed to explore the influences of Mn doping on the final structure of the resulting Mn/Ce oxides. The results demonstrate that the Mn exists in mixed chemical states of Mn(II)/(III)/(IV), and Ce (III)/Ce(IV) are also coexistent in the oxides. Facilitated by the multivalent states of Mn/Ce, the electron transfer becomes more efficient, thereby endowing the resulting Mn/Ce oxides excellent catalytic activity and wide temperature adaptability in the oxidation of 3,3 ',5,5 '-tetramethylbenzidine (TMB) in the presence of O2, featuring an oxidase mimic behavior. The catalytic conditions, stability and reusability were also evaluated. By leveraging the excellent oxidase-mimicking activity of Mn/Ce(III) for ascorbic acid (AA) was developed using TMB as the chromogenic substrate, achieving a linear range of 10-80 mu M with a detection limit of 6.88 mu M. Finally, a smartphone assisted sensing method for AA was explored using an RGB model to monitor the color change and absorbance of the target reaction system. This work highlights a straightforward approach to fabricate an excellent nanozyme with smart sensing capability for target molecules.

The zeolite-catalyzed one-step lactide production process from lactic acid has garnered significant attention owing to its alignment with green chemistry principles. Within this process, the shape selectivity and internal Bronsted acid sites of the zeolites serve as the critical determinants for lactide production. In this study, a hierarchical ZSM-5 with phosphorus-active sites (denoted as TBP-CZSM-5) was synthesized via a hydrothermal synthesis method using cetyltrimethylammonium bromide (CTAB) and tetrabutylphosphonium hydroxide (TBPOH) as the dual templates. Characterization results confirmed that hierarchical TBP-CZSM-5 exhibited a stacked-nanorod architecture (similar to 40 nm) with increased mesopore volume and specific surface area. Phosphorus modification increased weak Bronsted acid sites while preserving the zeolite's inherent strong acid sites. The modification led to a significant increase in lactide (LT) selectivity compared to P-free TBA-CZSM-5, achieving a final lactide yield of 60%. These findings offer new design principles for tuning acidic properties of zeolites and developing sustainable catalytic systems for the one-pot LA-to-LT conversion.

During the study of hydrothermal synthesis of nickel-encapsulated zeolite catalyst using the ligand-protection method, uniform nanofibers (similar to 10 nm diameter, hundreds of nanometers long) were unexpectedly observed on the surface of zeolite crystals. These nanofibers were subsequently synthesized independently outside the zeolite synthesis system and were identified as nickel-kerolite, a kind of talc-like nickel phyllosilicate. An optimal synthesis approach of the nickel phyllosilicate fibers was realized via a hydrothermal method using a synthetic gel comprising a silicon source, sodium hydroxide, nickel nitrate, and ethylenediamine (EDA). It is found that the formation of the unique fibrous morphology of nickel phyllosilicate requires a sufficiently strong alkaline medium and the presence of EDA. Ethylenediamine was proven to be essential for achieving the nano-fibrous morphology, probably due to the anisotropic growth inhibition from both EDA and its nickel complex (Ni-EDA), which restrict crystal development predominantly along one direction.

By utilizing the flexible multi-electron nature of polyoxometalates (POMs) to broaden the electron transfer paths and promote the electron exchange, a new approach for improving the catalytic activity of MOFs-based nanozymes is proposed. Herein, a vanadium-POM was incorporated into a Co-MOF through a one-pot procedure to construct the V10O28@Co-MOF. Structural characterization demonstrates that the V10O28 was chemically immobilized within the Co-MOF skeleton via coordinative interactions. The model oxidation of 3,3 ',5,5 '-tetra-methylbenzidine (TMB) was utilized to assess the oxidase-like activity of the resulting V10O28@Co-MOF. In contrast, the V10O28@Co-MOF exhibits distinctly enhanced oxidase-like activity compared to the single Co-MOF. It also demonstrates catalytic stability under acidic conditions, and tolerance against salts and operational temperatures. Comparison with previous studies, the resulting V10O28@Co-MOF shows excellent substrate affinity and a faster reaction rate (Vmax = 2.1524 & times; 10-3 mM/min). Building on these findings, the resulting V10O28@Co-MOF could be further applied for the sensitive detection of ascorbic acid (AA) and cysteine (L-Cys), with detection limits of 1.796 mu M and 1.860 mu M, respectively, over a broader concentration range. This work provides a good solution to improve the oxidase mimic activity of MOFs-based nanozymes, and shows a promising application in rapid colorimetric sensing of target molecules.

Metal-organic frameworks (MOFs), a class of porous crystalline materials with tunable coordination structures, offer unique opportunities for CO2 photoreduction; however, their application in piezo-photocatalysis remains limited by poor visible-light absorption, high structural symmetry, and low polarity. Herein, we report a CN-grafting strategy that anchors carbon-nitrogen (CN) species onto coordination-unsaturated Ni sites of Ni-BDC, constructing NiM-CN with a grafting-induced internal electric field (IEF). This modification enhances the structural asymmetry and polarity, thereby strengthening piezoelectric polarization and generating a polarization-induced electric field (PEF) under mechanical stimulation conditions, as demonstrated by the increased piezoelectric coefficient (d33, from 42.41 to 82.16 pm V-1 compared to the reference sample). Meanwhile, CN grafting narrows the band gap and strengthens the IEF in NiM-CN through Ni 3d-N 2p orbital hybridization and asymmetric charge redistribution. The synergistic effect of IEF and PEF accelerates charge separation and transfer, leading to enhanced surface charge accumulation, as confirmed by in situ Kelvin probe force microscopy (KPFM). Consequently, NiM-CN achieves a remarkable CO production rate of 3406.36 µmol g-1 h-1 under piezo-photocatalytic conditions. This work establishes grafting-induced IEF engineering as an effective strategy for constructing coupled electric-field systems in MOFs for efficient piezo-photocatalysts.

Mesoporous molecular sieve-supported metals have been widely investigated as catalysts for the removal of tetracycline (TC) from water via a "preconcentration-activation-degradation" catalytic system. However, the design and construction of bimetallic catalysts supported on MCM-41 for TC degradation remains a challeng. In this study, highly dispersed Al-Fe3N species within MCM-41(Al-Fe3N/Al-MCM-41) was successfully prepared, where Al originates from Al-MCM-41 subjected to high-temperature dealumination. In the presence of Al-Fe3N/Al-MCM-41 and PDS, 98.5% of TC was efficiently degraded within 60 min. The corresponding reaction rate constant (0.07262 min-1) was 2.92 times that of Fe3N/MCM-41 (0.02486 min-1). The excellent degradation performance is attributed to the enhanced electron cloud density of Fe induced by Al doping, thereby enhancing the activation efficiency of peroxydisulfate (PDS). At the same time, micro-mesoporous structure in Al-Fe3N/Al-MCM-41 is beneficial to preconcentration of target contaminants for the enhancement of degradation efficiency. In addition, the disinfection performance of Al-Fe3N/Al-MCM-41 system against antibiotic-resistant bacteria and its device-level application were explored. This work provides a novel strategy to fabricate MCM-41 with doping Fe3N species for the water treatment. This strategy provides a new perspective for the rational utilization of Al atoms via high-temperature dealumination method.