Dynamic carboxymethyl chitosan prodrug hydrogel precisely mediates robust therapy on wound infection.

Dynamic antibacterial polysaccharide prodrug hydrogels are in great demand for treatment of wound infection owing to their unique advantages such as excellent biocompatibility, superior antimicrobial property as well as favorable wound healing capacity. Herein, this work highlights the successful development of a dynamic carboxymethyl chitosan (CMC) prodrug hydrogel, which is facilely constructed through Schiffer base reaction between antibacterial components (amikacin and CMC) and crosslinker (dialdehyde PEG). Moderate dynamic imine linkages endow the hydrogel with excellent injectable and self-healing capability as well as targeted on-demand drug release in slightly alkaline condition at infected wound. All ingredients and their strong intermolecular interactions endow the hydrogel with favorable swelling and moisture retention capability. Moreover, the covalent and non-covalent interactions also endow the hydrogel with superior adhesion and mechanical property. These attractive characteristics enable hydrogel to effectively kill pathogens, promote wound healing and reduce side effects of amikacin. Thereby, such a dynamic CMC prodrug hydrogel may open a new avenue for a robust therapy on wound infection, greatly advancing their use in clinics.

Enhancing the Stability of 4.6 V LiCoO2 Cathode Material via Gradient Doping.

LiCoO2 (LCO) can deliver ultrahigh discharge capacities as a cathode material for Li-ion batteries when the charging voltage reaches 4.6 V. However, establishing a stable LCO cathode at a high cut-off voltage is a challenge in terms of bulk and surface structural transformation. O2 release, irreversible structural transformation, and interfacial side reactions cause LCO to experience severe capacity degradation and safety problems. To solve these issues, a strategy of gradient Ta doping is proposed to stabilize LCO against structural degradation. Additionally, Ta1-LCO that was tuned with 1.0 mol% Ta doping demonstrated outstanding cycling stability and rate performance. This effect was explained by the strong Ta-O bonds maintaining the lattice oxygen and the increased interlayer spacing enhancing Li+ conductivity. This work offers a practical method for high-energy Li-ion battery cathode material stabilization through the gradient doping of high-valence elements.

Engineering a Novel AgMn2O4@Na0.55Mn2O4 Nanosheet toward High-Performance Electrochemical Capacitors.

Manganese oxides, as a type of two-dimensional (2D) material with high specific area and low cost, are considered promising energy storage materials. Here, we report novel AgMn2O4/Na0.55Mn2O4 nanosheets created by a popular liquid precipitation method with different AgNO3 contents, and their corresponding physical and electrochemical characterizations are performed. The results show that the ultra-thin Na0.55Mn2O4 nanosheets were combined with the AgMn2O4 nanoparticles and an enhancement in their specific capacity was observed compared to the pristine sheets. This electrode material displays a peak specific capacitance of 335.94 F g-1 at 1 A g-1. Using an asymmetric supercapacitor (ASC) assembled using a positive electrode made of AgMn2O4/Na0.55Mn2O4 nanosheets and a reduced graphene oxide (rGO) negative electrode, a high energy density of 65.5 Wh kg-1 was achieved for a power density of 775 W kg-1. The ASC showed good cycling stability with a capacitance value maintained at 90.2% after 10,000 charge/discharge cycles. The excellent electrochemical performance of the device was ascribed to the heterostructures and the open space formed by the interconnected manganese oxide nanosheets, which resulted in a rapid and reversible faraday reaction in the interface and further enhanced its electrochemical kinetics.

Structural, elastic and electronic properties of atomically thin pyridyne: theoretical predictions.

In this paper, we propose a new acetylenic carbon material called pyridyne, which is composed of acetylenic linkages and pyridine rings. From first-principles calculations, we investigate the structural, elastic and electronic properties of pyridyne. It is found that the structure of pyridyne is stable at 300 K and its stability is comparable to experimentally synthesized graphdiyne and graphtetrayne. Compared with graphene or graphyne, pyridyne possesses more diverse pores and reduced delocalization of electrons. The in-plane stiffness of pyridyne is 183 N m-1 with a Poisson's ratio of 0.304. Pyridyne is found to be a semiconductor with a direct band gap of 0.91 eV. The intrinsic electron mobility can reach 6.08 × 104 cm2 V-1 s-1, while the hole mobility can reach 1.82 × 104 cm2 V-1 s-1.

Synthesis of BiPO4 by crystallization and hydroxylation with boosted photocatalytic removal of organic pollutants in air and water.

Environmental photocatlytsis has been considered as a promising alternative strategy to address the current environmental threats and pressures. Fabrication of the photocatalysts with high efficiency, stability and bio-safety is the core of photocatalytic applications. Herein, we report a facile approach to synthesize monazite BiPO4 (SHTW) with high crystallization and hydroxylation. The wide bandgap of the SHTW can provide strong redox abilities to produce reactive species and mineralize organic pollutants. Its high crystallinity and dipole moment can promote separation and transportation of the photoexcited electron-hole pairs effectively. In addition, the hydroxylation can produce more highly oxidizing hydroxyl radicals and further improve charge carrier separation. Notably, the hydroxylation can be reborn and the high crystallization can be maintained during photocatalysis. Thus, a virtuous cycle can be established and organic pollutants can be removed efficiently. The mineralization rate of 146.1 µmol g-1 h-1 can be obtained on the SHTW for photocatalytic degradation of benzene, which is about 8.5 times higher than that of the commercial TiO2 (P25). Various dyes, dyes mixture and bisphenol A can all be completely degraded over the SHTW. It shows the potential application and value in environmental governance.

First-principles study of structural, elastic and electronic properties of naphyne and naphdiyne.

The structural, elastic and electronic properties of 2D naphyne and naphdiyne sheets, which consist of naphthyl rings and acetylenic linkages, are investigated using first-principles calculations. Both naphyne and naphdiyne belong to the orthorhombic lattice family and exhibit the Cmmm plane group. The structural stability of naphyne and naphdiyne are comparable to those of experimentally synthesized graphdiyne and graphtetrayne, respectively. The increase of acetylenic linkages provides naphdiyne with a larger pore size, a lower planar packing density and a lower in-plane stiffness than naphyne. Naphyne is found to be an indirect semiconductor with a band gap of 0.273 eV, while naphdiyne has no band gap and has a Dirac point. The band gaps of naphyne and naphdiyne are found to be modified by applied strain in the elastic range. These facts make naphyne and naphdiyne potential candidates for a wide variety of membrane separations and for fabrication of soft and strain-tunable nanoelectronic devices.

Self-Assembly of CdS/CdIn2S4 Heterostructure with Enhanced Photocascade Synthesis of Schiff Base Compounds in an Aromatic Alcohols and Nitrobenzene System with Visible Light.

A series of novel CdS/CdIn2S4 composite materials were prepared via a one-pot solvothermal process. The as-obtained photocatalysts were characterized by several techniques and the photocatalytic properties of CdS/CdIn2S4 photocatalysts were studied by photocascade synthesis of Schiff base compounds in a photocatalytic reaction system of aromatic alcohols and nitrobenzene irradiated with visible light. The results reveal that the resulting CdS/CdIn2S4 heterostructure samples show outstanding photocatalytic activities toward the photocascade production of Schiff base compounds in an aromatic alcohols and nitrobenzene reaction system irradiated with visible light. An optimized 50.0% CdS/CdIn2S4 heterostructure sample shows the highest Schiff base yield of 42.0% irradiated with visible light for 4 h, which is approximately 19.1 and 1.54 times higher than those of sole CdS and CdIn2S4 samples, respectively. The fabrication of heterogeneous structure improves the spatial separation and migration of photoinduced electron-hole pairs, thus contributing to the enhancement of photocatalytic properties. We foresee that this finding can offer a strategy to develop heterostructure composites for efficient synthesis of organics by photocatalysis under mild conditions.

Efficient utilization of photogenerated electrons and holes for photocatalytic redox reactions using visible light-driven Au/ZnIn2S4 hybrid.

In this study, a new photocatalytic reaction system for simultaneous selective oxidation of aromatic alcohols to corresponding aldehydes and reduction of protons to H2 has been developed. The results reveal that compared with pure ZnIn2S4, the ZnIn2S4 photocatalysts modified with noble metal gold (Au/ZnIn2S4) significantly promote the photocatalytic performance. Among them, the 0.5% Au/ZnIn2S4 nanosheets shows the highest photocatalytic activity for selective oxidation of benzyl alcohol to benzaldehyde and hydrogen production, and the yields of H2 and benzaldehyde are 326.68 and 352.04 µmol under visible light irradiation for 4 h, respectively. Those are about 4.4 and 3.6 times higher than those of pure ZnIn2S4 sample (74.0 µmol H2 and 98.04 µmol benzaldehyde), respectively. The utilization ratio of photogenerated electrons to holes can achieve 92.8%. Additionally, the control experiments demonstrate that the photogenerated electrons and holes play significant roles during the reaction process. It is hoped that the current work can offer an avenue to utilize the photogenerated carriers more efficiently and to develop other photocatalytic reaction systems, such as nitrogen fixation and reduction of carbon dioxide.

One-pot synthesis of Schiff base compounds via photocatalytic reaction in the coupled system of aromatic alcohols and nitrobenzene using CdIn2S4 photocatalyst.

The use of solar energy to drive organic reactions under mild conditions provides a sustainable pathway for green synthesis and has been one of the primary goals pursued by scientists. In this research, the cadmium indium sulfide (CdIn2S4) photocatalyst was prepared using a simple solvothermal method and was thoroughly characterized using X-ray powder diffraction, UV-visible absorption spectra, nitrogen adsorption-desorption isotherms, scanning electron microscopy, transmission electron microscopy and X-ray spectroscopy measurements. The photocatalytic performance of the CdIn2S4 photocatalyst was evaluated using photocatalytic synthesis of Schiff base compounds in a coupled system of aromatic alcohols and nitrobenzene under visible light irradiation. The yield of N-benzylideneaniline reached up to 32% in the coupled system of benzyl alcohol and nitrobenzene under visible light illumination for 8 h. Furthermore, the changes for the amounts of aromatic aldehydes and AL as intermediate products during the photocatalytic process were also investigated. Using isotopic tracing, a possible reaction mechanism for the photocatalytic synthesis of N-benzylideneaniline and the redox reactions in the coupled system of benzyl alcohol and nitrobenzene was proposed. It is hoped that this strategy can provide an effective pathway for the traditional organic synthesis and transformation using photocatalytic technology under mild conditions.

Structural and electronic properties of KY(BH4)4: DFT+U study.

The structure, composition, and electronic property of mixed-cation borohydrides are of significant importance for understanding and improving their thermodynamic and kinetic activities. Conventional density functional theory (DFT) fails to correctly describe the electronic structure of the system due to insufficient cancellation of the self-interaction energy and underestimation of the band gap. In the present work, we present a systematic investigation of the structural and electronic properties of KY(BH4)4 for the first time at the DFT+U level of theory. It is found that the LDA+U method underestimates the lattice volume by ∼17.36%, while the PBE+U and PW91+U methods show good agreement with the experimental value at U = 3 and U = 4, respectively. The total energy of KY(BH4)4 calculated by PW91+U method at U = 4 is 0.97 eV lower than that calculated by PBE+U method at U = 3. We suppose that the PW91+U method is more suitable for the structural and electronic properties study of KY(BH4)4 due to the lower total energy. K+ connects with BH4 - complex through electrostatic attraction, while weak covalent interaction exists between Y3+ and BH4 - complex.

Solvothermal synthesis of CdIn2S4 photocatalyst for selective photosynthesis of organic aromatic compounds under visible light.

Ternary chalcogenide semiconductor, cadmium indium sulfide (CdIn2S4), was prepared by a simple solvothermal method using ethylene glycol as a solvent, as well as indium chloride tetrahydrate (InCl3.4H2O), cadmium nitrate tetrahydrate [Cd(NO3)2.4H2O], and thiacetamide (TAA) as precursors. The resulted sample was subject to a series of characterizations. It is the first time to use CdIn2S4 sample as a visible light-driven photocatalyst for simultaneous selective redox transformation of organic aromatic compounds. The results indicate that the as-synthesized CdIn2S4 photocatalyst not only has excellent photocatalytic performance compared with pure In2S3 and CdS for the selective oxidation of aromatic alcohols in an oxygen environment, but also shows high photocatalytic redox activities under nitrogen atmosphere. A possible mechanism for the photocatalytic redox reaction in the coupled system was proposed. It is hoped that our current work could extend the applications of CdIn2S4 photocatalyst and provide new insights for selective transformations of organic compounds.

Helical graphitic carbon nitrides with photocatalytic and optical activities.

Graphitic carbon nitride can be imprinted with a twisted hexagonal rod-like morphology by a nanocasting technique using chiral silicon dioxides as templates. The helical nanoarchitectures promote charge separation and mass transfer of carbon nitride semiconductors, enabling it to act as a more efficient photocatalyst for water splitting and CO2 reduction than the pristine carbon nitride polymer. This is to our knowledge a unique example of chiral graphitic carbon nitride that features both left- and right-handed helical nanostructures and exhibits unique optical activity to circularly polarized light at the semiconductor absorption edge as well as photoredox activity for solar-to-chemical conversion. Such helical nanostructured polymeric semiconductors are envisaged to hold great promise for a range of applications that rely on such semiconductor properties as well as chirality for photocatalysis, asymmetric catalysis, chiral recognition, nanotechnology, and chemical sensing.

Ferrocene-modified carbon nitride for direct oxidation of benzene to phenol with visible light.

Ferrocene moieties were heterogenized onto carbon nitride polymers by a covalent -C=N- linkage bridging the two conjugation systems, enabling the merging of the redox function of ferrocene with carbon nitride photocatalysis to construct a heterogeneous Photo-Fenton system for green organocatalysis at neutral conditions. The synergistic donor-acceptor interaction between the carbon nitride matrix and ferrocene group, improved exciton splitting, and coupled photocatalytic performance allowed the direct synthesis of phenol from benzene in the presence of H2 O2 under visible light irradiation. This innovative modification method will offer an avenue to construct functionalized two-dimensional polymers useful also for other green synthesis processes using solar irradiation.