Engineering Thermally Reduced Graphene Oxide for Synchronously Enhancing Photocatalytic Activity and Photothermal Effect.

The structural composition of reduced graphene oxide (rGO) can be modified and controlled by appropriate reduction methods to modulate its electronic structure, rendering it a versatile platform for tailoring optoelectronic and catalytic properties. Nevertheless, it is uncommon to concurrently amplify the photocatalytic and photothermal effects when regulating and utilizing pure rGO. Here, we investigate the impact of structural variations in thermally reduced graphene oxide (TGO) on its photocatalytic and photothermal properties. Various characterization results demonstrate that appropriate thermal reduction facilitates the preservation and transformation of oxygenated groups and structure defects, which in turn encourages the formation of reactive carbon radicals and discrete graphitic domains, thereby strengthening the activation of molecular oxygen and the plasmonic photothermal effect under near-infrared (NIR) light irradiation. Moreover, the optimized TGOs exhibit efficient sterilization with NIR irradiation due to enhanced photocatalytic activities and photothermal effects. This work highlights the potential for developing photocatalytic and photothermal rGO-based materials through structural engineering.

Curcumin-regulated constructing of defective zinc-based polymer-metal-organic framework as long-acting antibacterial platform for efficient wound healing.

A dual-modal antibacterial platform has been established for highly efficient wound healing infected by bacteria based on a defective zinc-based metal-organic framework composite, which was synthesized using 1,4-phthalic acid-based polyether polymer (L8) as ligand, curcumin as regulator, and Zn2+ as metal coordinated center (Cur@Zn-MOF). In addition to the integration of the features of polymer-MOF synthesized using L8 (such as high water stability and controllable and long-term release of Zn2+) and Zn-bioMOF prepared using curcumin as ligand (such as feasible release of curcumin and Zn2+ and good biocompatibility), the Cur@Zn-MOF bioplatform also possessed plenty of structure defects. Comparing with Zn-bioMOF and polyZn-MOF synthesized using the sole ligand, the smaller released amount of curcumin (6.08 µg mL-1) and higher release level of Zn2+ ions (5.68 µg mL-1) were simultaneously achieved for the defective Cur@Zn-MOF within a long-term duration (48 h). The synergistic effect afforded Cur@Zn-MOF the high sterilization performance toward Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) even at the low usage of 125 µg mL-1. The in vivo wound healing effect further confirmed the superior treatment ability of Cur@Zn-MOF toward the bacterium-infected wound. Also, the negligible cytotoxicity and low hemolysis of Cur@Zn-MOF greatly promoted the viability of human skin fibroblasts. Accordingly, this work can provide a new dual-modal bioplatform based on the functional MOF via the controllable release of antibacterial drug and metal ions for the efficient wound healing.

Structural Reconstruction Strategy Enables CoFe LDHs for High-Capacity NH4 + Storage and Application in High-Energy Density Ammonium-Ion Hybrid Supercapacitors.

Exploration of high-performance aqueous ammonium-ions hybrid supercapacitor has attracted tremendous research attention recently. Herein, structural reconstructed cobalt-iron layered double hydroxides (SR-CoFe LDHs) featuring copious structure defects (i. e., oxygen-vacancies, M-O bonds, MOO- bonds, coexistence of Co2+ /Co3+ and Fe2+ /Fe3+ ) are reported as a high-capacity cathode for NH4 + storage. The resulting SR-CoFe LDHs can deliver a reversible capacity of 167.9 mAh g-1 at 0.5 A g-1 , which is 3.3 folds higher than that of pristine CoFe-LDHs. Ex-situ experimental results and theoretical studies denote that the presence of structural defects in the CoFe-LDHs can lower the NH4 + adsorption energy and induced electron delocalization to enhance the electrical conductivity, rendering the CoFe-LDHs exhibits excellent performance for NH4 + storage. As a proof of concept, ammonium-ion hybrid supercapacitor has been assembled with CoFe-LDHs as the cathode and hierarchical carbon as the anode, which can deliver a large specific capacitance of 238.3 F g-1 , long cycle stability over 10000 cycles, and high energy density of 66.2 Wh kg-1 within a wide working voltage of 2 V. Overall, this work offers some insights into the design of high capacity cathode for aqueous NH4 + storage and also illustrates the construction of aqueous hybrid devices with NH4 + as the charge carrier.

Fully Condensed Poly (Triazine Imide) Crystals: Extended π-Conjugation and Structural Defects for Overall Water Splitting.

Conventional polymerization for the synthesis of carbon nitride usually generates amorphous heptazine-based melon with an abundance of undesired structural defects, which function as charge carrier recombination centers to decrease the photocatalytic efficiency. Herein, a fully condensed poly (triazine imide) crystal with extended π-conjugation and deficient structure defects was obtained by conducting the polycondensation in a mild molten salt of LiCl/NaCl. The melting point of the binary LiCl/NaCl system is around 550 °C, which substantially restrain the depolymerization of triazine units and extend the π-conjugation. The optimized polymeric carbon nitride crystal exhibits a high apparent quantum efficiency of 12 % (λ=365 nm) for hydrogen production by one-step excitation overall water splitting, owing to the efficient exciton dissociation and the subsequent fast transfer of charge carriers.

Structure Defect Tuning of Metal-Organic Frameworks as a Nanozyme Regulatory Strategy for Selective Online Electrochemical Analysis of Uric Acid.

Nanozymes have been designed to address the limitations of high cost and poor stability involving natural enzymes in analytical applications. However, the catalytic efficiency of the nanozyme still needs to be improved so that it can meet the selectivity and stability requirements of accurate biomolecule analysis. Here, we presented structure defects of metal-organic frameworks (MOFs) as a tuning strategy to regulate the catalytic efficiency of artificial nanozymes and investigated the roles of defects on the catalytic activity of oxidase-like MOFs. Structural defects were introduced into a novel Co-containing zeolitic imidazolate framework with gradually loosened morphology (ZIF-L-Co) by doping cysteine (Cys). It was found that with the increase in defect degree, the properties of materials such as ascorbate oxidase-like, glutathione oxidase-like, and laccase-like were obviously enhanced by over 5, 2, and 3 times, respectively. In-depth structural investigations indicate that the doping of sulfur inducing structural defects which may destroy the equilibrium state between cobalt and nitrogen in 2-methylimidazole and distort the crystal lattice, thereby enhancing the adsorption of oxygen and thus promoting the oxidase-like activity. The ZIF-L-Co-10 mg with enhanced ascorbate oxidase- and laccase-like activity was loaded into a microreactor and integrated into an online electrochemical system (OECS) in the upstream of the detector. This nanozyme-based microreactor can completely remove ascorbic acid, dopamine, and 3,4-dihydroxyphenylacetic acid which are the main interference toward uric acid (UA) electrochemical measurement, and the ZIF-L-Co-10 mg Cys-based OECS system is capable of continuously capturing UA change in rat brain following ischemia-reperfusion injury. Structure defect tuning of ZIF-L-Co not only provides a new regulatory strategy for artificial nanozyme activity but also provides a critical chemical platform for the investigation of UA-related brain function and brain diseases.

Porous Covalent Organic Polymers for Efficient Fluorocarbon-Based Adsorption Cooling.

Adsorption-based cooling is an energy-efficient renewable-energy technology that can be driven using low-grade industrial waste heat and/or solar heat. Here, we report the first exploration of fluorocarbon adsorption using porous covalent organic polymers (COPs) for this cooling application. High fluorocarbon R134a equilibrium capacities and unique overall linear-shaped isotherms are revealed for the materials, namely COP-2 and COP-3. The key role of mesoporous defects on this unusual adsorption behavior was demonstrated by molecular simulations based on atomistic defect-containing models built for both porous COPs. Analysis of simulated R134a adsorption isotherms for various defect-containing atomistic models of the COPs shows a direct correlation between higher fluorocarbon adsorption capacities and increasing pore volumes induced by defects. Combined with their high porosities, excellent reversibility, fast kinetics, and large operating window, these defect-containing porous COPs are promising for adsorption-based cooling applications.

Ultralow Lattice Thermal Conductivity in SnTe by Incorporating InSb.

Herein, a series of (Sn1.06Te)1-x-(InSb)x (x = 0, 0.025, 0.05, 0.075) samples are fabricated, and their thermoelectric performances are studied. The all-scale structure defects containing the atomic-scale In doping defects, the nanoscale Sb precipitates, and the mesoscale grain boundary scatter phonons collectively in a wide range of frequencies to give the ultralow lattice thermal conductivity. Concurrently, the incorporation of InSb decreases carrier concentration with marginal loss in carrier mobility, resulting in a little variation of electrical properties over a wide temperature range. The significantly decreased thermal conductivity and the preserved high power factor lead to a maximum ZT value of ∼0.84 at 823 K in the (Sn1.06Te)0.95(InSb)0.05 sample. This strategy of rapidly constructing all-scale structure defects could be applied to other thermoelectric systems to enhance thermoelectric performance.

The catalytic oxidation performance of toluene over the Ce-Mn-Ox catalysts: Effect of synthetic routes.

Ce-Mn-Ox catalysts were synthesized by impregnation (CM-IM), co-precipitation (CM-CP), citrate sol-gel (CM-SG) and hydrothermal (CM-HT) methods. The synthesis methods exhibited a great impact on the physicochemical properties of catalysts, resulting in different catalytic activity. The catalytic oxidation activity of toluene followed the sequence: CM-HT (T50: 234 °C; T90: 246 °C) > CM-SG (T50: 242 °C; T90: 249 °C) > CM-CP (T50: 243 °C; T90: 259 °C) > CM-IM (T50: 251 °C; T90: 261 °C), which was consistent with the sequence of surface relative percentage of Cov, Ce3+, Mn3+, Oα and r values. Among them, CM-HT showed the best catalytic oxidation performance of toluene due to more structural defects, oxygen vacancies, surface adsorption oxygen, normalized conversion rate and other active species. In addition, CM-HT catalysts showed reliable water resistance and good durability, implying the potential industrial application.

Intracardiac echogenic focus and its location: association with congenital heart defects.

Purpose: Significance of intracardiac echogenic focus (ICEF) in the fetal heart remains controversial. We aimed to investigate whether the location of ICEF is associated with fetal cardiac structure defects (CSDs) in low-risk pregnant women. Materials and Methods: A retrospective cohort study was conducted. Singleton pregnancies with normal values of triple fetal serum markers were included. 758 of 9782 fetuses with ICEF were reviewed for involvement of three ICEF locations (left, right, and bilateral ventricles (BVs)) in CSDs. χ2 or Fisher's exact test was performed for statistical analysis. Results: ICEF prevalence was 7.7% and its location was most frequently in the left ventricle (LV) (84.8%), followed by the BV (11.6%) and the right ventricle (RV) (3.6%). No statistically significant difference was found between the ICEF location and maternal age (χ2 = 3.92, p-value = .1409). There were cardiac defects with an isolated echogenic focus in 24 of 758 fetuses (3.2%). Significant difference for CSDs was observed among groups of RV, LV, and BV (p-fisher = .0146). Conclusions: Significantly more CSDs cases were identified in fetuses with ICEF in RV. Further investigation is warranted to examine the histological characteristics of fetal echogenic focus in the RV.

Edge-Rich Quasi-Mesoporous Nitrogen-Doped Carbon Framework Derived from Palm Tree Bark Hair for Electrochemical Applications.

Biomass with abundant resources and low price is regarded as potential sources of functionalized carbon-based energy storage and conversion electrode materials. Rational construction and development of biomass-derived carbon equipped with proper morphology, structure, and composition prove the key to highly efficient utilization of advanced energy storage systems. Herein, we use palm tree bark hair as a biomass source and prepare edge/defect-rich quasi-mesoporous carbon (QMC) by a direct pyrolysis followed by NaOH etching strategy. Then, the edge-rich quasi-mesoporous nitrogen-doped carbon (QMNC) is successfully fabricated through the hydrothermal method by making use of edge/defect-rich QMC and urea as carbon precursor and nitrogen source, respectively. The microstructure and composition of the resultant carbon materials are all detected by a series of techniques. In the meantime, the influence of the etching process on the preparation and electrochemical performance of edge-rich QMNC is systematically explored. The relevant results manifest that the as-prepared edge/defect-rich QMC not only possesses edge-rich plane, much increased specific surface area (SSA), and special quasi-mesopores but also reverses good conductivity and gains sufficient defects for subsequent N doping. After introducing N atoms, the obtained edge-rich QMNC exhibits outstanding capacitive property and oxygen reduction reaction performance, which are mainly attributed to the co-effect of edge-rich plane, large SSA, suitable pore structures, and effective N doping (including high doping amount and optimized N configurations). Clearly, our work not only offers an excellent biomass-derived carbon-based electrode material but also opens a fresh avenue for the development of advanced biomass-derived carbon-based electrode materials.

Cyclic Martensitic Transformations Influence on the Diffusion Of Carbon Atoms in Fe-18 wt.%Mn-2 wt.%Si alloy.

A significant carbon diffusion mobility acceleration as a result of cyclic γ↔ε martensitic transformations in iron-manganese alloy is determined by one- and two-dimensional structure defects of ε-martensite with face-centered close-packed lattice. Such defects (dislocations, low angle sub-boundaries of dislocations, chaotic stacking faults) were formed during cyclic γ↔ε martensitic transformations. Peak carbon diffusion coefficient increase was observed under thermocycling when maximum quantity of lattice defects increase was fixed.

Temperature-Driven Structural and Morphological Evolution of Zinc Oxide Nano-Coalesced Microstructures and Its Defect-Related Photoluminescence Properties.

In this paper, we address the synthesis of nano-coalesced microstructured zinc oxide thin films via a simple thermal evaporation process. The role of synthesis temperature on the structural, morphological, and optical properties of the prepared zinc oxide samples was deeply investigated. The obtained photoluminescence and X-ray photoelectron spectroscopy outcomes will be used to discuss the surface structure defects of the prepared samples. The results indicated that the prepared samples are polycrystalline in nature, and the sample prepared at 700 °C revealed a tremendously c-axis oriented zinc oxide. The temperature-driven morphological evolution of the zinc oxide nano-coalesced microstructures was perceived, resulting in transformation of quasi-mountain chain-like to pyramidal textured zinc oxide with increasing the synthesis temperature. The results also impart that the sample prepared at 500 °C shows a higher percentage of the zinc interstitial and oxygen vacancies. Furthermore, the intensity of the photoluminescence emission in the ultraviolet region was enhanced as the heating temperature increased from 500 °C to 700 °C. Lastly, the growth mechanism of the zinc oxide nano-coalesced microstructures is discussed according to the reaction conditions.