As-prepared Samples Research Articles

Double-Shelled Fe-Fe3C Nanoparticles Embedded on a Porous Carbon Framework for Superior Lithium-Ion Half/Full Batteries.

Cost-effective and environmentally friendly Fe-based active materials offer exceptionally high energy capacity in lithium-ion batteries (LIBs) due to their multiple electron redox reactions. However, challenges, such as morphology degradation during cycling, cell pulverization, and electrochemical stability, have hindered their widespread use. Herein, we demonstrated a simple salt-assisted freeze-drying method to design a double-shelled Fe/Fe3C core tightly anchored on a porous carbon framework (FEC). The shell consists of a thin Fe3O4 layer (≈2 nm) and a carbon layer (≈10 nm) on the outermost part. Benefiting from the complex nanostructuring (porous carbon support, core-shell nanoparticles, and Fe3C incorporation), the FEC anode delivered a high discharge capacity of 947 mAh g-1 at 50 mA g-1 and a fast-rate capability of 305 mAh g-1 at 10 A g-1. Notably, the FEC cell still showed 86% reversible capacity retention (794 mAh g-1 at 50 mA g-1) at a high cycling temperature of 80 °C, indicating superior structural integrity during cycling at extreme temperatures. Furthermore, we conducted a simple solid-state fluorination technique using the as-prepared FEC sample and excess NH4F to prepare iron fluoride-carbon composites (FeF2/C) as the positive electrode. The full cell configuration, consisting of the FEC anode and FeF2/C cathode, reached a remarkable capacity of 200 mAh g-1 at a 20 mA g-1 rate or an energy density of approximately 530 Wh kg-1. Thus, the straightforward and simple experimental design holds great potential as a revolutionary Fe-based cathodic-anodic pair candidate for high-energy LIBs.

Enhancing Ni/Co Activity by Neighboring Pt Atoms in NiCoP/MXene Electrocatalyst for Alkaline Hydrogen Evolution.

Density functional theory (DFT) calculations demonstrate neighboring Pt atoms can enhance the metal activity of NiCoP for hydrogen evolution reaction (HER). However, it remains a great challenge to link Pt and NiCoP. Herein, we introduced curvature of bowl-like structure to construct Pt/NiCoP interface by adding a minimal 1 ‰-molar-ratio Pt. The as-prepared sample only requires an overpotential of 26.5 and 181.6 mV to accordingly achieve the current density of 10 and 500 mA cm-2 in 1 M KOH. The water dissociation energy barrier (Ea) has a ~43 % decrease compared with NiCoP counterpart. It also shows an ultrahigh stability with a small degradation rate of 10.6 μV h-1 at harsh conditions (500 mA cm-2 and 50 °C) after 3000 hrs. X-ray photoelectron spectroscopy (XPS), soft X-ray absorption spectroscopy (sXAS), and X-ray absorption fine structure (XAFS) verify the interface electron transfer lowers the valence state of Co/Ni and activates them. DFT calculations also confirm the catalytic transition step of NiCoP can change from Heyrovsky (2.71 eV) to Tafel step (0.51 eV) in the neighborhood of Pt, in accord with the result of the improved Hads at the interface disclosed by in situ electrochemical impedance spectroscopy (EIS) and scanning electrochemical microscopy (SECM) tests.

B, S co-doped mesoporous carbon as an efficient catalyst for H2O2 electrosynthesis in natural seawater

The small-scale electrochemical synthesis of hydrogen peroxide (H2O2) in marine environments is of great significance for environmental wastewater treatment, and the design of electrocatalysts for complicated marine conditions is the key for this technology. Although B-doped carbon materials have been demonstrated to be resistant to Cl− poisoning, the deposition of Ca2+ on the surface of catalyst in seawater and the sluggish reaction kinetics of non-metallic catalysts remain to be solved. Herein, B, S co-doped mesoporous carbon materials were synthesized by a simple NaCl template method. The H2O2 yield of the as-prepared sample was up to 3.66 mol/(gcat h) with a Faradaic Efficiency (FE) of 97.98 % at 100 mA/cm2 in natural seawater, and achieved 100 % inactivation of bacteria and Chlorella within 5 min at a low current density. Based on the structural characterization and electrochemical results, the S-containing structure on the carbon matrix suppresses Ca2+ deposition due to its excellent proton adsorption activity. Furthermore, the electron transfer process between the reactant and BC3 was enhanced by the abundant mesoporous structure, so as to optimize the sluggish oxygen reduction reaction (ORR) kinetics on BC3. This work offers a strategy for inactivation of marine microorganisms and the degradation of organic pollutants, which promotes the advancement of marine wastewater treatment technology, and also provides reference for the design of metal free catalysts used in marine environments.

CuS-CuO nanoparticles for antennas collect light through their conductivity by absorbing a single photon located at the wavelength of 254 nm

CuS-CuO nanoparticles were prepared by air annealing as-made CuS nanoparticles deposited using spray pyrolysis. The optical, structural, and morphological properties of samples were investigated by UV–VIS Spectroscopy, X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and Atomic Force Microscopy (AFM). The XRD analysis of as-prepared sample include two phases CuS and Cu2S, while annealed films are a mixture of CuS and CuO phases. The dimensions of the CuS crystallites were estimated by Williamson's method on the diffraction peaks (81 nm) while the dimensions of the CuO ones were statistically evaluated via the SEM image (95 nm) and corroborated by Williamson's method on the diffraction peaks (98 nm). SEM study of annealed samples reveals that nanoparticles are monocrystalline. Optical analysis shows more than 80 % transmittance through sample thickness 164 nm in the infrared region and two energy bandgaps of 1.92 and 2.50 eV in the visible region associated with CuO and CuS, respectively. In addition, we observe after several optical excitations that only the UV wavelength of 254 nm gives a tangible electrical response. We understand from the literature that this is only possible through one interpretation of the antenna effect. Optical antennas aim to freely change light rays into local energy. In fact, our sample presents nanoparticles with sizes around 80 nm that show clear absorption through the development of their reproducible resistance that increases with polarization toward saturation after 5 V. Therefore, we propose using prepared nanoparticles in a light-harvesting antenna for artificial photodetector and other optoelectronic applications.

Novel sr-doped NdMn0.5Cr0.5O3-δ electrodes for symmetrical solid oxide fuel cell

Solid oxide fuel cells (SOFCs) have emerged as promising energy conversion devices, offering high efficiency and environmental sustainability. Efficient electrode materials are crucial for the overall cell performance of SOFCs. Perovskite type Nd1-xSrxMn0.5Cr0.5O3-δ (x = 0.25, 0.5) (NSCM25, NSCM50) was synthesized via conventional solid-state reaction technique. Structural, thermal and electrochemical characterizations were performed using X-ray diffraction, thermogravimetric analysis, conductivity measurements, scanning electron microscope, thermal expansion coefficient analysis and impedance spectroscopy. Structural analysis revealed that both compositions exhibit orthorhombic symmetry in the Pbnm space group. Thermogravimetric analysis (TGA) indicated minimal weight changes in both pre-reduced and as-prepared samples. The electrical conductivities in air at 600 ℃ were found to be 1.69 S/cm for NSCM25 and 4.91 S/cm for NSCM50, with a decrease observed under reduced oxygen partial pressure. Polarization resistance (Rp) analysis was conducted on symmetrical cells composed of NSCM25|GDC|NSCM25, NSCM50|GDC|NSCM50, NSCM25|YSZ|NSCM25, and NSCM50|YSZ|NSCM50. At 900 ℃, the polarization resistances were 0.12 Ωcm2, 0.21 Ωcm2, 0.11 Ωcm2, and 0.67 Ωcm2, respectively. The results suggest that NSCM25 and NSCM50 hold promise as electrode materials for symmetrical solid oxide fuel cells (SSOFC) employing YSZ or GDC electrolyte.

An Experimental Approach to Assess Fluorine Incorporation into Disordered Rock Salt Oxide Cathodes.

Disordered rock salt oxides (DRX) have shown great promise as high-energy-density and sustainable Li-ion cathodes. While partial substitution of oxygen for fluorine in the rock salt framework has been related to increased capacity, lower charge-discharge hysteresis, and longer cycle life, fluorination is poorly characterized and controlled. This work presents a multistep method aimed at assessing fluorine incorporation into DRX cathodes, a challenging task due to the difficulty in distinguishing oxygen from fluorine using X-ray and neutron-based techniques and the presence of partially amorphous impurities in all DRX samples. This method is applied to "Li1.25Mn0.25Ti0.5O1.75F0.25" prepared by solid-state synthesis and reveals that the presence of LiF impurities in the sample and F content in the DRX phase is well below the target. Those results are used for compositional optimization, and a synthesis product with drastically reduced LiF content and a DRX stoichiometry close to the new target composition (Li1.25Mn0.225Ti0.525O1.85F0.15) is obtained, demonstrating the effectiveness of the strategy. The analytical method is also applied to "Li1.33Mn0.33Ti0.33O1.33F0.66" obtained via mechanochemical synthesis, and the results confirm that much higher fluorination levels can be achieved via ball-milling. Finally, a simple and rapid water washing procedure is developed to reduce the impurity content in as-prepared DRX samples: this procedure results in a ca. 10% increase in initial discharge capacity and a ca. 11% increase in capacity retention after 25 cycles for Li1.25Mn0.25Ti0.50O1.75F0.25. Overall, this work establishes new analytical and material processing methods that enable the development of more robust design rules for high-energy-density DRX cathodes.

Synthesis and study of optical properties of a Gd3+-doped NaYF4 phosphor for phototherapy lamp application.

In recent trends, radiation falls under the narrowband ultraviolet-B region (305-315 nm) widely used in phototherapy lamp applications in the treatment of skin diseases. In this paper, we report a Gd3+-doped NaYF4 luminescent material synthesized for the first time using the low-temperature co-precipitation method. It crystallized into a face-centred cubic structure, as confirmed by X-ray diffraction characterization techniques and Rietveld refinement. The photoluminescence property of the as-prepared sample shows a highly intense, sharp emission band obtained at 311 nm, which belongs to the narrowband ultraviolet-B region and corresponds to the transition of the 6P7/2→8S7/2 level of the Gd3+ ions under 272 nm excitation (8S7/2 to 6IJ). The transitions of the Gd3+ ions are detected entirely with different concentrations of Gd3+ ions. Scanning electron microscopy analysis indicated that the average particle was 288 nm. The critical distance for energy transfer was calculated to be equal to 11.5017 Å. Dipole-dipole interaction is responsible for energy transfer, as analyzed by Dexter theory. These excellent optical characteristics, together with their highly efficient and low-cost synthesis approach, indicate that synthesized NaYF4:Gd3+ phosphors have excessive potential for phototherapeutic lamp applications.

Coupling amorphous WO3 with WP as a cocatalyst for efficient dye-sensitizated photocatalytic hydrogen evolution

Tungsten phosphide (WP) as an excellent hydrogen evolution reactions (HER) catalyst has attracted widespread attention, but its HER activity is low in alkaline media due to high water dissociation barrier. Herein, noble-metal-free cocatalyst WP/WO3 composite was synthesized by adjusting the P/W molar ratio in the raw material using a simple solid phosphidation reaction. The structure, morphology, composition, and optoelectronic properties of the as-synthesized samples were characterized by XRD, SEM, TEM, XPS, UV–vis DRS, PL techniques, and electrochemical methods. Under visible light irradiation (λ ≥ 420 nm), the photocatalytic HER activities of the as-prepared samples using Eosin-Y (EY) dye as a sensitizer and trimethylamine (TMA) as an electron donor were investigated. The result shows that WP/WO3 composite as a cocatalyst exhibits excellent photocatalytic HER activity and good stability. The highest apparent quantum yield (AQY) reaches 32.8 %. The presence of amorphous WO3 in crystalline WP can improve the separation efficiency of photogenerated electrons and holes, reduce HER overpotential, and promote the dissociation of H2O in alkaline media. Therefore, the photocatalytic HER activity of WP/WO3 composite is higher than that of single crystalline WP.

Phase transition and large strain response with ultra-low hysteresis of BaTiO3 doped with a high-entropy perovskite oxide

(1 − x)BaTiO3–xBi(Sc0.2Y0.2Al0.2Fe0.2Ga0.2)O3 (BT–BSYAFG, x = 0.02, 0.04, 0.06, 0.08, and 0.10) ceramics were successfully prepared via the solid-state reaction method. X-ray diffraction and Raman spectroscopy results reveal that a structural transition from the tetragonal (P4mm) to the pseudocubic (Pm3¯m) phase occurs with increasing x. At x = 0.04 and 0.06, the tetragonal and pseudocubic phases coexist. The relaxor behavior of the as-prepared samples is enhanced via BSYAFG doping due to the lattice distortion effect of high-entropy perovskite oxides. Additionally, the transition from the classic ferroelectric to the relaxor ferroelectric state implies that the long-range-ordered macro-domains are completely transformed into disordered polar nano-regions, which improves the strain properties. A large strain response (0.28 %) with an ultra-low hysteresis (4 %) is achieved at x = 0.06 under an electric field of 70 kV/cm. These results indicate that BT–BSYAFG ceramics are promising materials for application to the field of precision actuators.

Rapid, Massive, and Green Synthesis of Polyoxometalate-Based Metal-Organic Frameworks to Fabricate POMOF/PAN Nanofiber Membranes for Selective Filtration of Cationic Dyes.

Developing high-efficiency membrane materials for the rapid removal of organic dyes is crucial but remains a challenge. Polyoxometalates (POMs) clusters with anionic structures are promising candidates for the removal of cationic dyes via electrostatic interactions. However, their shortcomings, such as their solubility and inability to be mass-produced, hinder their application in water pollution treatment. Here, we propose a simple and green strategy utilizing the room temperature stirring method to mass produce nanoscale polyoxometalate-based metal-organic frameworks (POMOFs) with porous rhomboid-shaped dodecahedral and hexagonal prism structures. The products were labeled as POMOF1 (POMOF-PW12) and POMOF2 (POMOF-PMo12). Subsequently, a series of x wt% POMOF1/PAN (x = 0, 3, 5, and 10) nanofiber membranes (NFMs) were prepared using electrospinning technology, where polyacrylonitrile (PAN) acts as a "glue" molecule facilitating the bonding of POMOF1 nanoparticles. The as-prepared samples were comprehensively characterized and exhibited obvious water stability, as well as rapid selective adsorption filtration performance towards cationic dyes. The 5 wt% POMOF1/PAN NFM possessed the highest removal efficiency of 96.7% for RhB, 95.8% for MB, and 86.4% for CV dyes, which realized the selective separation over 95% of positively charged dyes from the mixed solution. The adsorption mechanism was explained using FT-IR, SEM, Zeta potential, and adsorption kinetics model, which proved that separation was determined via electrostatic interaction, hydrogen bonding, and π-π interactions. Moreover, the POMOF1/PAN membrane presented an outstanding recoverable and stable removal rate after four cycles. This study provides a new direction for the systematic design and manufacture of membrane separation materials with outstanding properties for contaminant removal.

Experimental and theoretical aspects of the growth of vertically aligned CNTs by CCVD on AZO substrate

An efficient and reproducible growth of vertically aligned carbon nanotubes by CCVD requires accurate and specific setting of the synthesis parameters and the properties of catalyst thin layers. In this work, the growth of vertically aligned carbon nanotubes onto AZO (= aluminum doped zinc oxide) glass substrate covered by Al2O3 and Fe-Co catalyst layer system is presented. Investigation of the effect of catalyst composition and synthesis temperature on CVD growth revealed the optimum condition of the synthesis. The analysis of as-prepared samples by SEM, TEM and Raman spectroscopy was carried out to prove the structure and quality of carbon deposit. Theoretical considerations have supported speculative ideas about the role of the support layer, the transformation of the catalyst layer in the presence of hydrogen gas and the growth mechanism of carbon nanotubes. The mechanism of CNT growth is modelled and the order of magnitude of experimentally observed vertical linear growth rate of CNT (several nm/s) is reproduced.

In situ construction of efficient electromagnetic function Graphene/PES composites based on liquid phase exfoliation strategy

Although graphene nanosheets (GNs) with huge specific surface area and exceptional electrical properties exhibit attractive practical prospect in the realm of electromagnetic function materials, how to optimize the distribution states of GNs in matrix is still a challenge. In this work, the suspension of GNs was prepared directly via an efficient liquid-phase exfoliation (LPE) process in N-octyl-2-pyrrolidone (NOP). Thanks to the dissolution of polyether sulfone (PES) in NMP and NOP solvent, the GNs/PES composites were in-situ prepared via a facile solution blending in combination with evaporation process. The “function units” of the mesoscopic micro-cluster structure assembled by GNs during the solvent evaporation process contribute to optimized impedance matching characteristics and loss capabilities as well as excellent electromagnetic wave (EMW) absorbing performance of the as-constructed GNs/PES electromagnetic composites. Particularly, the as-prepared sample G-P-9 with a graphene content of as low as 9.0 wt% exhibits outstanding EMW absorbing performance in the whole ranges of tested frequency (8.2–12.4 GHz) and temperature (293–453 K) with a minimum reflection loss (RL) of −52.7 dB. Besides, the in-situ self-assemble GNs/single-walled carbon nanotubes (GNs/SWCNT) film with pre-constructed three-dimensional interpenetrating conductive network exhibits excellent electromagnetic interference (EMI) shielding effectiveness (SE) of about 5.1 × 104 dB cm2 g−1. The present approach would be applicable to construct high-performance electromagnetic functional materials and broaden the application prospect of high-integrity graphene nanosheets.

Robust amorphous iron (II) diphosphate on nickel foam: Aggrandizing electronic structure for efficient catalytic activity towards oxygen evolution and urea oxidation

The few intuitive challenges are the high clean energy demand, the dire need for sustainable development, and low carbon footprints. Thereby, the wastewater rich in urea from sanitary units, and industries are subjected to produce green energy as a source for hydrogen through waste water-splitting. Thus, anodic reaction in electrochemical hydrogen production is the most widely promoted towards oxygen evolution reaction (OER) and urea oxidation reaction (UOR). However, both possess sluggish kinetics which need to be improved. Therefore, the development of novel materials that can meet the demands of both reaction mechanisms is highly required. Herein, Fe2P2O7-based composite grown on the conductive substrate can effectively enhance the electrical transportation of ions during electrocatalytic activity. The experimental and theoretical investigations are adopted to get a comprehensive insight and understanding of the catalytic nature of the as-prepared samples. Compared with other as-synthesized materials, Fe2P2O7 exhibits splendid performance with a low onset potential of 1.482 and 1.317 V (vs RHE) to obtain a current density of 10 mA/cm2 towards the OER and UOR process, respectively. The low Tafel slope and high turnover frequency offer low resistance during charge transfer. Additionally, greater ECSA and roughness factors enrich the attributes of Fe2P2O7 and offer more active sites for reaction to be held, producing a higher amount of gas bubbles. Hence, improved electrical conductivity, low charge transfer resistance, more electrochemical active surface area, and impressive durability reconfirm the Fe2P2O7 as an effective catalyst.

Synergistic lubrication effects of Sn–Ag–Cu and MXene–Ti3C2 to improve tribological properties of M50 bearing steel with microporous channels

Purpose This paper aims to study the synergistic lubrication effects of Sn–Ag–Cu and MXene–Ti3C2 to improve the tribological properties of M50 bearing steel with microporous channels. Design/methodology/approach M50 matrix self-lubricating composites (MMSC) were designed and prepared by filling Sn–Ag–Cu and MXene–Ti3C2 in the microporous channels of M50 bearing steel. The tribology performance testing of as-prepared samples was executed with a multifunction tribometer. The optimum hole size and lubricant content, as well as self-lubricating mechanism of MMSC, were studied. Findings The tribological properties of MMSC are strongly dependent on the synergistic lubrication effect of MXene–Ti3C2 and Sn–Ag–Cu. When the hole size of microchannel is 1 mm and the content of MXene–Ti3C2 in mixed lubricant is 4 wt.%, MMSC shows the lowest friction coefficient and wear rate. The Sn–Ag–Cu and MXene–Ti3C2 are extruded from the microporous channels and spread to the friction interface, and a relatively complete lubricating film is formed at the friction interface. Meanwhile, the synergistic lubrication of Sn–Ag–Cu and MXene–Ti3C2 can improve the stability of the lubricating film, thus the excellent tribological property of MMSC is obtained. Originality/value The results help in deep understanding of the synergistic lubrication effects of Sn–Ag–Cu and MXene–Ti3C2 on the tribological properties of M50 bearing steel. This work also provides a useful reference for the tribological design of mechanical components by combining surface texture with solid lubrication. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-12-2023-0381/

SiO2/WO3/ZnO based self-cleaning coatings for solar cells

The accumulation of pollution and any kinds of contamination on the glass cover of the solar cell affects the efficiency of the photovoltaic (PV) systems. The contamination on the glass cover can absorb and reflect a certain part of the sunlight irradiation, which can decrease the intensity of the light coming in through the glass cover. With the study, it was planned to develop self-cleaning coatings for the PV systems. It was aimed to prevent or reduce the contamination-induced efficiency loss of the existing PV systems. In the scope of the project, SiO2/WO3 and SiO2/WO3/ZnO composites were coated from their solutions on the glass substrates using a dip-coating technique. WO3 was selected as a photocatalyst semiconductor. Under the UV light irradiation, WO3 could absorb the photons of the UV light, generating the photoinduced charge carriers. The photoexcited charge carriers provide both the photoinduced hydrophilicity on the surface of the coating and the photocatalytic degradation of the organic contaminants accumulated on the surface of the coating, which allows water droplets to spread and flow on the surface of the cover glass to remove the contaminations. However, the recombination rate of the photoexcited charge carriers on the WO3 film was high. In order to suppress the recombination of the photoinduced charge carriers, WO3 was coupled with SiO2 and ZnO. Both of these semiconductors improved the photocatalytic activity of the WO3 film. Although SiO2 has superior features in terms of the light transmission, it was not very effective under UV light as a photocatalyst alone. The widely preferred photocatalyst ZnO was added into the composite film structure to enhance the photocatalytic activity. The self-cleaning mechanism of the film coatings on a solar cell was investigated through the photocatalytic dye removal efficiency on the as-prepared film samples. There was a slight decrease in the light transparency and the solar cell efficiency because of the WO3 content of the composite film. On the other hand, coupling the SiO2/WO3 film with ZnO enhanced the photocatalytic activity, and it suppressed the reduction effect of the WO3 phase on both the light transparency and the solar cell efficiency. The photocatalytic dye removal efficiency was increased to over 90% after 240 min of UVA light irradiation. In addition, the solar cell coated with the SiO2/WO3/ZnO film provided almost the same solar cell efficiency as the uncoated solar cell. The water contact angle measurement also exhibited the photocatalytic degradation of the model contamination on the glass cover of the solar cell under the UVA light irradiation.Graphical

Perovskite oxides (LaFeO3) incorporated with reduced graphene oxide for electromagnetic interference shielding

In this work, lanthanum iron (III) oxide (LaFeO3)/reduced graphene (rGO)-based nanocomposites were synthesized using a chemical route. The as-prepared samples were subjected to calcination at 700°C. To classify their structural and morphological properties, the nanocomposites were characterized using X-ray diffraction (XRD) and transmission electron microscopy. The findings showed that the nanocomposites obtained were 20 nm and had undergone diameter changes at 700°C after calcination. The XRD analysis revealed that the composites had a strong crystalline single-phase structure. In addition, the Voigt theory was used to compute elastic constants such as Young’s modulus (E), bulk modulus (K), shear modulus (G), Poisson’s ratio and linear compressibility. The computational structural characteristics of lanthanum iron (III) oxide perovskites were also examined. The microwave absorption properties of lanthanum iron (III) oxide/rGO nanocomposites made them appropriate for electromagnetic interference shielding usage.

Effect of MOF-derived nanoparticle-cumulated flower-like CoFe@C coated composites on hydrogenation/dehydrogenation performance of MgH2

Magnesium hydride (MgH2) has garnered substantial consideration mainly due to its high gravimetric density and reliable resource, whereas its poor thermodynamics and kinetics for absorbing/releasing hydrogen restricts the largescale application. Certain catalysts have demonstrated remarkable activity in enhancing the hydrogen storage capabilities of MgH2. In this work, the nanoparticle-cumulated flower-like CoFe@C coated catalysts (denoted as CoFe@C) are controllably synthesized as expected by the MOF (Metal-Organic Farmwork) in-suit decomposition method at 800 °C, which exhibits an average pore size of 18.63 nm. Meanwhile, the particle size for the as-prepared CoFe alloy coated in carbon layer are approximately 10–20 nm, and the as-prepared samples are introduced to promote the de/rehydrogenation properties of MgH2 at relatively lower temperatures. Due to the synergistic interaction of CoFe alloy nanoparticles serving as active sites and agglomeration resistance of carbon layers, the MgH2 composites doped with CoFe@C-800 could initialize its decomposition process at 175.9 °C, and may desorb 6.0 wt% H2 at 300 °C in 400 s. Additionally, the peak temperature and apparent activation energy during dehydrogenation decline significantly (with 35 % and 38 %, respectively). Furthermore, theoretical analysis results indicate a higher catalytic activity for the carbon-coated CoFe alloy owing to the synergetic effect between CoFe nanocomposite & carbon layer, which can facilitate the bond extension and strength decrease of Mg-H bonding. In brief, using MOF may derive transition metal and carbon layer, which could be a promising approach to stimulating the hydrogen storage properties of MgH2.

Rational design of complex quantum dots decorated ceria nanorods for efficient visible-light driven nitrogen fixation

Ceria-based materials, as very active photocatalysts for redox reactions, have been widely investigated, but there are few reports on nitrogen photofixation. Herein, complex dots of Cu2O/Cu-C decorated CeO2 nanorods with an overall photocatalytic nitrogen fixation process are considered. Remarkable photocatalytic performances are obtained by adjusting the band gap structures and surface activity site status. The as-prepared sample has excellent visible light absorption capacity, more photoinduced oxygen defects and excellent nitrogen absorption ability. The ammonia yield is approximately 1124 µmol·gcal−1·h−1 under light irradiation with no sacrificial agents, increasing approximately 8.5 times compared with the Cu-decorated sample. The apparent quantum efficiency at 420 nm is also more than 1.1%. This work may provide a new avenue for the efficient design of photocatalytic materials without any precious metals.

Graphene-Wrapped ZnO Nanocomposite with Enhanced Room-Temperature Photo-Activated Toluene Sensing Properties.

Graphene-wrapped ZnO nanocomposites were fabricated by a simple solvothermal technology with a one-pot route. The structure and morphology of these as-fabricated samples were systematically characterized. The adding of graphene enhanced the content of the oxygen vacancy defect of the sample. All gas-sensing performances of sensors based on as-prepared samples were thoroughly studied. Sensors displayed an ultrahigh response and exceptional selectivity at room temperature under blue light irradiation. This excellent and enhanced toluene gas-sensing property was principally attributed to the synergistic impacts of the oxygen vacancy defect and the wrapped graphene in the composite sensor. The photo-activated graphene-wrapped ZnO sensor illustrated potential application in the practical detection of low concentrations of toluene under explosive environments.

Titanium dioxide and halloysite loaded polylactic acid-based membrane continuous flow photoreactor for 17α-ethinylestradiol (EE2) hormone degradation: Optimization, kinetics, mechanism, and reusability study

Exposure to endocrine-disrupting chemicals (EDCs) has been linked to harmful effects in biota due to their widespread chemical persistence. In this paper, we report on the fabrication of electrospun polylactic acid (PLA) based nanofibers functionalized with TiO2 nanoparticles. The PLA-based TiO2 nanofibers were further stabilized with the incorporation of halloysite (HNT) particles. The nanofibers were fabricated in varied concentrations of HNT (5, 10, 15%), while TiO2 was kept at 10% for all the prepared samples. The fabricated samples were evaluated for elimination of synthetic 17α-ethinylestradiol (EE2) hormone as a model EDC pollutant. By using combined adsorptive and photocatalytic processes, the as-prepared samples were evaluated in a continuous flow system under dark and UV-light irradiation for EE2 removal. The best-performing sample with an optimized concentration of PLA/TiO2/HNT (85, 10, 5%) was able to eliminate 71.6% of EE2 hormone under UV irradiation at a hormone concentration of 0.1 mg/L. The maximum removal capacity obtained was 1.26 mg/g in 2 h, which best fitted the pseudo-first-order kinetics model. The sample was further utilized for additional experiments by changing experimental parameters, such as contact time, solution pH, and flow rate. To elucidate the actual degradation of the EE2 hormone, LCMS analysis was carried out to monitor the formation of by-products, which indicated that EE2 was fragmented into different potentially benign molecules. Finally, the best-performing sample was utilized for ten cyclic runs under optimized conditions for which the sample maintained sufficiently high degradation without any loss in structural integrity. Overall, the results showed that the developed PLA/TiO2/HNT nanofibers have a high potential to target persistent organic pollutants.