Visible Light-Induced Photocatalysis:Self-Fenton Degradation of p-CIPhOH Over Graphitic Carbon Nitride by a Polyethylenimine Bifunctional Catalyst

Deep degradation of organic pollutants by sunlight-induced coupled photocatalytic and Fenton (photo-Fenton) reactions is of immense importance for water purification. In this work, we report a novel bifunctional catalyst (Fe-PEI-CN) by codoping graphitic carbon nitride (CN) with polyethyleneimine ethoxylated (PEI) and Fe species, which demonstrated high activity during p-chlorophenol (p-ClPhOH) degradation via H_(2)O_(2) from the photocatalytic process. The relationship between the catalytic efficiency and the structure was explored using diff erent characterization methods. The Fe modification of CN was achieved through Fe-N coordination, which ensured high dispersion of Fe species and strong stability against leaching during liquid- phase reactions. The Fe modification initiated the Fenton reaction by activating H_(2)O_(2) into ·OH radicals for deep degradation of p-ClPhOH. In addition, it eff ectively promoted light absorption and photoelectron-hole (e-h ^(+) ) separation, corresponding to improved photocatalytic activity. On the other hand, PEI could significantly improve the ability of CN to generate H_(2)O_(2) through visible light photocatalysis. The maximum H_(2)O_(2) yield reached up to 102.6 μmol/L, which was 22 times higher than that of primitive CN. The cooperation of photocatalysis and the self-Fenton reaction has led to high-activity mineralizing organic pollutants with strong durability, indicating good potential for practical application in wastewater treatment.

NMR assisted studies on the solution structures and functions of antimicrobial peptides Dedicated to Professor Chaohui Ye on the occasion of his 80th birthday

Microbial resistance has now become a global public health concern,and the spread of multidrug-resistant bacteria also threatens human health.Antimicrobial peptides(AMPs)are a class of small peptides with antibacterial,anti-inflammatory,anti-infective,antioxidation,anti-tumor,antiviral functions and immune regulation activities.Due to the small sizes,their structures are easily studied by nuclear magnetic resonance(NMR)techniques.Compared to traditional antibiotics,AMPs have specific antibacterial mechanisms,and do not easily result in the production of drug-resistant strains.Thus,the development of new antimicrobial peptides and their wide use instead of chemical antibiotics are of great significance to human health.In this review,we first summarized the relationship between the structures and functions of antimicrobial peptides.Then,we focused on examples,cathelicidins,a group of cationic antimicrobial peptides with multiple biological activities.Especially,cathelicidin BF30 or BF34,composed of 30 or 34 amino acids,were from the venom glands of the Bungarus fasciatus snake and were considered to be the most active antibacterial peptides among different cathelicidin members.Their solution structures determined by NMR are a-helixes,which are useful in designing new and stable peptides with similar framework,including stapple peptides by inducing chemical modifications in the sidechains of some residues,as well as cyclic peptides by inducing disulfide bond between cysteines in the sequences.

High-Performance Na-Ion Storage of S-Doped Porous Carbon Derived from Conjugated Microporous Polymers

Na-ion batteries(NIBs)have attracted considerable attention in recent years owing to the high abundance and low cost of Na.It is well known that S doping can improve the electrochemical performance of carbon materials for NIBs.However,the current methods for S doping in carbons normally involve toxic precursors or rigorous conditions.In this work,we report a creative and facile strategy for preparing S-doped porous carbons(SCs)via the pyrolysis of conjugated microporous polymers(CMPs).Briefly,thiophene-based CMPs served as the precursors and doping sources simultaneously.Simple direct carbonization of CMPs produced S-doped carbon materials with highly porous structures.When used as an anode for NIBs,the SCs exhibited a high reversible capacity of 440 mAh g?1 at 50 mA g?1 after 100 cycles,superior rate capability,and excellent cycling stability(297 mAh g?1 after 1000 cycles at 500 mA g?1),outperforming most S-doped carbon materials reported thus far.The excellent performance of the SCs is attributed to the expanded lattice distance after S doping.Furthermore,we employed ex situ X-ray photoelectron spectroscopy to investigate the electrochemical reaction mechanism of the SCs during sodiation-desodiation,which can highlight the role of doped S for Na-ion storage.

Radiation-induced cross-linking:a novel avenue to permanent 3D modification of polymeric membranes

Membrane fouling is always the biggest problem in the practice of membrane separation technologies,which strongly impacts their applicability,separation efficiency,cost effectiveness,and service lifespan.Herein,a simple but effective 3D modification approach was designed for permanently functionalizing polymeric membranes by directly cross-linking polyvinyl alcohol(PVA)under gamma-ray irradiation at room temperature without any additives.After the modification,a PVA layer was constructed on the membrane surface and the pore inner surface of polyvinylidene fluoride(PVDF)membranes.This endowed them with good hydrophilicity,low adsorption of protein model foulants,and easy recoverability properties.In addition,the pore size and distribution were customized by controlling the PVA concentration,which enhanced the rejection ability of the resultant membranes and converted them from microfiltration to ultrafiltration.The crosslinked PVA layer was equipped with the resultant membranes with good resistance to chemical cleaning by acidic,alkaline,and oxidative reagents,which could greatly prolong the membrane service lifetime.Furthermore,this approach was demonstrated as a universal method to modify PVDF membranes with other hydrophilic macromolecular modifiers,including polyethylene glycol,sodium alginate,and polyvinyl pyrrolidone.This modification of the membranes effectively endowed them with good hydrophilicity and antifouling properties,as expected.

Construction of Au@Metal-organic framework for sensitive determination of creatinine in urine

Creatinine level in urine is an important biomarker for renal function diseases,such as renal failure,glomerulonephritis,and chronic nephritis.The Au@MIL-101(Fe)was prepared by in situ growth of Au nanoparticles in MIL-101(Fe)as a selective SERS substrate.The Au@MIL-101(Fe)offers the great local surface plasmon resonance(SPR)effect due to gold nanoparticles aggre-gation inside metal-organic frameworks.The framework structure could enrich trace target samples and drag them into SPR hot spots.The optimal Au@MIL-101(Fe)composite substrate is used for analyzing creatinine in urine and the limit of detection is down to 0.1μmol/L and a linear relationship is ranging from 1μmol/L to 100μmol/L.

MOFs-Based Nitric Oxide Therapy for Tendon Regeneration

Tendon regeneration is still a great challenge due to its avascular structure and low self-renewal capability.The nitric oxide(NO)therapy emerges as a promising treatment for inducing the regeneration of injured tendon by angiogenesis.Here,in this study,a system that NO-loaded metal–organic frameworks(MOFs)encapsulated in polycaprolactone(PCL)/gelatin(Gel)aligned coaxial scaffolds(NMPGA)is designed and prepared for tendon repair.In this system,NO is able to be released in vitro at a slow and stable average speed of 1.67 nM h^−1 as long as 15 d without a burst release stage in the initial 48 h.Furthermore,NMPGA can not only improve the tubular formation capability of endothelial cells in vitro but also obviously increase the blood perfusion near the injured tendon in vivo,leading to accelerating the maturity of collagen and recovery of biomechanical strength of the regenerated tendon tissue.As a NO-loaded MOFs therapeutic system,NMPGA can promote tendon regeneration in a shorter healing period with better biomechanical properties in comparison with control group by angiogenesis.Therefore,this study not only provides a promising scaffold for tendon regeneration,but also paves a new way to develop a NO-based therapy for biomedical application in the future.

Stability study of Disperse Blue 79 under ionizing radiation

Ionizing radiation is a promising method for dye degradation or textile coloration using commercial azo dyes and small molecular weight organic dyes. Thus, the stability of the molecular structure of an azo dye is important under ionizing radiation. Disperse Blue 79, as an example azo dyes, was irradiated with gamma rays or electron beam (EB) to investigate the radiation-induced effects on the molecular structure. Ultraviolet visible spectroscopy (UV Vis), nuclear magnetic resonance (NMR) spectra analysis, and mass spectrometry (MS) studies indicated that acetoxy and methoxyl were easily cleaved on the irradiation of the aqueous dye solution but retained a stable structure on the irradiation of the powder form. Gamma rays and EB showed similar effects on the decomposition process. Chromaticity changes using the Lab* method showed that the dye turned to dark yellow and the value of b* of the irradiated dyes increased with the increasing absorbed dose, which indicated that Disperse Blue 79 could be partly decomposed in an aqueous solution This work was nancially supported by the National Natural Science Foundation of China (Nos. 11875313, 11605274, and 11575277). Xiao-Jun Ding and Ming Yu contributed equally to this work. & Jing-Ye Li jyli@shnu.edu.cn 1 Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China 2 University of Chinese Academy of Sciences, Beijing 100049, China 3 The Education Ministry Key Lab of Resource Chemistry, Shanghai Key Lab of Rare Earth Functional Materials, College of Chemistry and Materials Science, Shanghai Normal University, Shanghai 200234, China with an absorbed dose of 10 kGy. Furthermore, the results demonstrated that the chemical stability of the Disperse Blue 79 under ionizing radiation are different in its powder form with the dye in the aqueous solution.

Fabrication of stable MWCNT bucky paper for solar-driven interfacial evaporation by coupling c-ray irradiation with borate crosslinking

Herein,we report a facile solution process for preparing multi-walled carbon nanotube(MWCNT)bucky paper for solar-driven interfacial water evaporation.This process involves vacuum filtrating a dispersion of MWCNTs that was modified by polyvinyl alcohol(PVA)under c-ray irradiation on a cellulose acetate microporous membrane,followed by borate crosslinking.Fourier transform infrared spectroscopy,Raman spectroscopy,and thermogravimetry confirmed the success of PVA grafting onto MWCNTs and borate crosslinking between modified MWCNT nanoyarns.The as-prepared crosslinked MWCNT bucky papers(BBP membranes)were used as a solar absorber,by placing them on a paper-wrapped floating platform,for interfacial water evaporation under simulated solar irradiation.The BBP membranes showed good water tolerance and mechanical stability,with an evaporation rate of 0.79 kg m^(-2)h^(-1)and an evaporation efficiency of 56%under 1 sun illumination in deionized water.Additionally,the BBP membranes achieved an evaporation rate of 0.76 kg m^(-2)h^(-1)in both NaCl solution(3.5 wt%)and sulfuric acid solution(1 mol L-1),demonstrating their impressive applicability for water reclamation from brine and acidic conditions.An evaporation rate of 0.70 kg m-2 h-1(very close to that from deionized water)was obtained from the solar evaporation of saturated NaCl solution,and the BBP membrane exhibited unexpected stability without the inference of salt accumulation on the membrane surface during long-term continuous solar evaporation.

Introduction to the special issue on surface-enhanced Raman spectroscopy and functionalized plasmonic nanoparticles for biomedical applications

Since its first discovery in 1974 from the enhanced Raman spectra of pyridine molecules on roughened silver surface,surface-enhanced Raman spectrosco-py(SERS)has garnered significant attention in the field of chemistry,biology,and medicine.With the sensitivity of down to single-molecule level and the intrinsic"fingerprint"spectrum,SERS enables the ultra-sensitive,specific,selective,and multi-plexing label-free analysis of a trace of molecules in aqueous biological environments,minus the inter-ference from water,white-light or tissue auto-fluorescence background.

Pressure-dependent band-bending in ZnO:A near-ambient-pressure X-ray photoelectron spectroscopy study

ZnO-based catalysts have been intensively studied because of their extraordinary performance in lower olefin synthesis,methanol synthesis and water-gas shift reactions.However,how ZnO catalyzes these reactions are still not well understood.Herein,we investigate the activations of CO_(2),O_(2)and CO on single crystalline ZnO polar surfaces at room temperature,through in-situ near-ambient-pressure X-ray photoelectron spectroscopy(NAP-XPS).It is revealed that O_(2)and CO_(2)can undergo chemisorption on ZnO polar surfaces at elevated pressures.On the ZnO(0001)surface,molecular CO_(2)(O_(2))can chemically interact with the top layer Zn atoms,leading to the formation of CO_(2)^(δ-)(O_(2)^(δ-))or partially dissociative atomic oxygen(O-)and hence the electron depletion layer in ZnO.Therefore,an apparent upward band-bending in ZnO(0001)is observed under the CO_(2)and O_(2)exposure.On the ZnO(0001)surface,the molecular chemisorbed CO_(2)(O_(2))mainly bond to the surface oxygen vacancies,which also results in an upward bandbending in ZnO(0001).In contrast,no band-bending is observed for both ZnO polar surfaces upon CO exposure.The electron-acceptor nature of the surface bounded molecules/atoms is responsible for the reversible binding energy shift of Zn 2 p_(3/2)and O 1 s in ZnO.Our findings can shed light on the fundamental understandings of CO_(2)and O_(2)activation on ZnO surfaces,especially the role of ZnO in heterogeneous catalytic reactions.

A new trick on an old support: Zr in situ defects-created carbon nitride for efficient electrochemical nitrogen fixation

Electrochemical nitrogen reduction reaction(NRR) to produce ammonia under ambient conditions is considered as a promising approach to tackle the energy-intensive Haber-Bosch process,but the low Faradaic efficiency and yield of NH_3 are still a challenge.Herein,a carbon-vacancies enriched mesoporous g-C_3 N_4 is developed by an in situ Zr doping strategy.The in situ mesoporous-forming mechanism is deeply understood by TPSR to reveal the functions of Zr dopant that pulls C from the precursor of C_3 N_4,resulting the formation of homogeneous mesopores with about 57% of the one C-defective s-triazine ring in C_3 N_4.Due to the defect sites obtained in metal doping synthesis,the RuAu bimetallic supported catalyst(RuAu_3/0.3 Zr-C_3 N_4) exhibits effective NRR performance with a Faraday efficiency of 11.54% and an NH_3 yield of 5.28 μg h^(-1) mg_(cat) ^(-1).at-0.1 V(RHE),which is nearly 10 times higher than that of RuAu_3/C_3 N_4 catalyst.This work proposes a simple and template-free preparation method for the high defect density mesoporous C_3 N_4,and provides new possibilities of a wide application of mesopore g-C3 N4.

Barley leaves mediated biosynthesis of Au nanomaterials as a potential contrast agent for computed tomography imaging

Over the past few years, environment-friendly green synthetic methods for metal nanoparticles(NPs) have received considerable attention. The use of plant extracts is considered as potential for the biosynthesis of metal NPs due to its easier obtainment, cheap accessibility to industrial scale-up and high biosecurity. Herein, with the aqueous leaf extract of barley leaves as the template, we reported a rapid, single step, cost-effective and eco-friendly synthetic route to prepare new gold nanoparticles(BL-Au NPs).Significantly, except for the key role as the reducing, barley leaves was further utilized as the capping agent that ensure the stability of the BL-Au NPs. The characterization results of TEM, FTIR and UV-vis indicated that the gold nanoparticles coated with barley leaves extract were successfully synthesized. In vitro and zebra fish toxicity and stability assays demonstrated its good biocompatibility and high colloidal stability. The CT images in vitro demonstrated that the constructed BL-Au NPs possessed superiority in X-ray attenuation ability compared to clinically commonly used iodinated small molecular contrast agent. And BL-Au NPs can be used as contrast agent for effective CT imaging of zebra fish model. These results suggest the potential utility of BL-Au NPs as a CT imaging contrast agent in clinical CT imaging based diagnosis.

Photothermally Enhanced Dual Enzyme-mimic Activity of Gold-Palladium Hybrid Nanozyme for Cancer Therapy

Based on characteristics of the tumor microenvironment(TME),including acidity,hypoxia,inflammation and hydrogen peroxide overload,combined with emerging nanotechnologies,designing nanoplatforms with TME specificity/responsiveness for tumor treatment is a promising nanotherapeutic strategy.In this work,a multifunctional gold-palladium bimetallic cascade nanozyme was constructed for effective photothermal-enhanced cascade catalyzed synergistic therapy of tumors.The dumbbell-like Au-Pd bimetallic nanomaterial(Au NRs-Pd@HA)was obtained by reducing palladium on gold nanorods with ascorbic acid(AA)and further modified with hyaluronic acid(HA).The introduction of HA brings biocompatibility and targeting properties.The zebrafish embryos model showed that Au NRs-Pd@HA had good biocompatibility and low biotoxicity.Au NRs-Pd@HA can induce catalytic conversion of glucose to generate H_(2)O_(2) efficiently,and subsequently undergo cascade reaction to produce abundant·OH radicals,exhibiting peroxidase-like(POD-like)and glucose oxidase-like(GOD-like)capabilities.The generated·OH was a key factor for tumor ablation.Meanwhile,Au NRs-Pd@HA exhibits good photothermal performance under 808 nm irradiation,in favor of photothermal therapy(PTT).Especially,the POD-like and GOD-like activities were significantly enhanced due to the photothermal effect.The synergistic PTT and photothermal-enhanced nanozymes with cascade catalytic effect enabled efficient and safe cancer therapy.

Microwave-assisted synthesis of oxygen vacancy associated TiO_(2)for efficient photocatalytic nitrate reduction

The solar-driven photocatalytic technology has shown great potential in nitrate(NO_(3)^(-))pollutants reduction,however,it has been greatly hindered by the complex preparation and high cost of photocatalysts.Herein,a relatively low-cost photocatalyst,rutile and anatase mixed phase TiO_(2) was synthesized by a facile microwave-hydrothermal method.Meanwhile,oxygen vacancy is successfully generated,leading to an acidic surface for strong adsorption towards NO_(3)^(-),which further improved the reduction activity.Compared with the commercial P25,a higher NO_(3)^(-) conversion of ca.100%and nitrogen(N_(2)) selectivity of 87%were achieved under UV(365 nm)irradiation within 2 h.This research provides a promising strategy for designing efficient noble metal free photocatalyst in the NO_(3)^(-) reduction.

Deoxygenative alkylation of tertiary amides using alkyl iodides under visible light

It is an unceasing goal for organic chemists to develop new catalytic methodologies for functional group transformations of widespread molecular structures. Amides are readily available from simple and reliable reactions, which are common structural units found in biologically active compounds. Consequently, they are attractive to be exploited in amine synthesis by reductive cross coupling. However, deoxygenative functionalization of amides is a long-standing challenge owing to the inertness of the resonance-stabilized amide C=O bond. In this work, a deoxygenative alkylation strategy was demonstrated, which combines amides and alkyl iodides to build structurally diverse tertiary alkylamines in a single step. Compared with previous deoxygenative alkylation of amides using organometallic reagents as functional partner, this work uses stable and easily available alkyl halides as functionalization reagents. The versatile and flexible strategy plus structural and functional diversity of readily available amides and alkyl iodides renders it highly appealing for the streamlined synthesis of tertiary amines and would be of much interest in areas such as pharmaceutical and agrochemical research.

Synthesis of amidines via iron-catalyzed dearomative amination of β-naphthols with oxadiazolones

An iron-catalyzed dearomative amination of β-naphthols via a nitrene-transfer process has been developed.Oxadiazolones,which have rarely been applied for the synthesis of amidines,are used as the nitrene source.A variety of amidines bearing β-naphthalenone moieties were generated smoothly in good to high yields(up to 98%)in the presence of 1.5 equivalents of tetrabutylammonium bromide,which was added as an essential additive.

A Stable Luminescent Covalent Organic Framework Nanosheet for Sensitive Molecular Recognition

Despite rapid advances in fluorescence detectors over the past decade,the development of a highly stable,sensitive,and selective fluorescence platform for molecular recognition remains a considerable challenge.Here we report a stable carbazole-based sp2 carbon fluorescence covalent organic framework(COF)nanosheet,termed a JUC-557 nanosheet.Owing to the synergistic effect of aggregation-induced emission-and aggregation-caused quenching-based chromophores,the architecture of the JUC-577 shows high absolute quantum yields(up to 23.0%)in the solid state and when dispersed in various solvents as well as excellent sensing performance toward specific analytes,such as iodine(Ka:2.10×10^(5)M−1 and LOD:302 ppb),2,4,6-trinitrotoluene(Ka:4.38×10^(5)M−1 and LOD:129 ppb),and especially nitrobenzene(Ka:6.18×10^(6)M−1 and LOD:5 ppb)that is superior to that of fluorescence detection materials reported so far.Furthermore,the JUC-557 nanosheet preserves strong luminescence and sensitive recognition,even under harsh conditions,and allows trace detection of various analytes via a handheld UV lamp.These findings pave the way for developing stable ultrathin COF nanomaterials for highly sensitive and selective molecular detection.

Boosting the photocatalytic nitrogen reduction to ammonia through adsorption-plasmonic synergistic effects

Ammonia is one of the most essential chemicals in the modern society but its production still heavily relies on energy-consuming Haber-Bosch processes.The photocatalytic reduction of nitrogen with water for ammonia production has attracted much attention recently due to its synthesis under mild conditions at room temperature and atmospheric pressure using sunlight.Herein,we report a high-performance Au/MIL-100(Cr)photocatalyst,comprising MIL-100(Cr)and Au nanoparticles in photocatalytic nitrogen reduction to ammonia at ambient conditions under visible light irradiation.The optimized photocatalyst(i.e.,0.10Au/MIL-100(Cr))achieved the excellent ammonia production rate with 39.9μg g_(cat)^(-1) h^(-1) compared with pure MIL-100(Cr)(2.73μg gcat^(-1) h^(-1)),which was nearly 15 times that on pure MIL-100(Cr).The remarkable activity could be attributed to the adsorption-plasmonic synergistic effects in which the MIL-100(Cr)and Au are responsible to the strong trapping and adsorption of N2 molecules and photo-induced plasmonic hot electrons activating and decomposing the N2 molecules,respectively.This study might provide a new strategy for designing an efficient plasmonic photocatalyst to improve the photocatalytic performance of N2 fixation under visible light irradiation.

Pore Engineering for Covalent Organic Framework Membranes

Membrane technology is of particular significance for the sustainable development of society owing to its potential capacity to tackle the energy shortage and environmental pollution.Membrane materials are the core part of membrane technology.Researchers have always been pursuing predictable structures of advanced membrane materials,which provides a possibility to fully unlock the potential of membranes.Covalent organic frameworks(COFs),with the advantage of controllable pore microenvironment,are considered to be promising candidates to achieve this design concept.The customizable function of COF membranes through pore engineering does well in the enhancement of selective permeability performance,which offers COF membranes with great application potentials in separation and transportation fields.In this context,COF-based membranes have been developed rapidly in recent years.Herein,we present a brief overview on the strategies developed for pore engineering of COF membranes in recent years,including skeleton engineering,pore surface engineering,host-guest chemistry and membrane fabrication.Moreover,the features of transmission or separation of molecules/ions based on COF membranes and corresponding applications are also introduced.In the last part,the challenges and prospects of the development of COF membranes are discussed.

Biphenyl-Induced Superhelix in L-Phenylalanine-Based Supramolecular Self-Assembly with Dynamic Morphology Transitions

Dynamic transitions of supramolecular assemblies between lower-order structures and higher-order superhelical structures(e.g.,double-helical DNA,helical biopolymers)are of vital importance in many physiological processes,but still remain a great challenge to be realized in artificially assembled systems.Herein,a novel biphenyl central core symmetrically coupled with phenylalanine groups drives the construction of the dynamic superhelix.