Boosted Light Alkane Deep Oxidation via Metal Bond Length Modulation-Induced C-C Bond Preferential Activation.

Light alkanes (LAs), typical VOCs existing in both stationary and mobile sources, pose significant environmental concerns. Although noble metal catalysts demonstrate strong C-H bond activation, their effectiveness in degrading LAs is hindered by inherent challenges, including poor chemical stability and water resistance. Here, from a new perspective, we propose a feasible strategy that adjusting the metal bond lengths within Pd clusters through partial substitution of smaller radius 3d transition metals (3dTMs) to prioritize the activation of low-energy C-C bonds within LAs. Benefiting from this, PdCo/CeO2 exhibits exceptional catalytic performance in propane degradation due to their high capacity for C-C cleavage stemming from the shorter Pd-Co length (2.51 Å) and lower coordination number (1.73), boosting the activation of α-H and ß-H of propane simultaneously and accelerating the mobility of postactivated oxygen species to prevent Pd center deep oxidation. The presence of 3dTMs on Pd clusters improves the redox and charge transfer ability of catalysts, resulting in an amplified generation of oxygen vacancies and facilitating the adsorption and activation of reactants. Mechanistic studies and DFT calculations suggest that the substitution of 3dTMs significantly accelerate C-C bond cleavage within C3 intermediates to generate the subsequent C2 and C1 intermediates, suppressing the generation of harmful byproducts.

Low-Temperature Propane Activation and Mineralization over a Co3O4 Sub-nanometer Porous Sheet: Atomic-Level Insights.

Light alkanes make up a class of widespread volatile organic compounds (VOCs), bringing great environmental hazards and health concerns. However, the low-temperature catalytic destruction of light alkanes is still a great challenge to settle due to their high reaction inertness and weak polarity. Herein, a Co3O4 sub-nanometer porous sheet (Co3O4-SPS) was fabricated and comprehensively compared with its bulk counterparts in the catalytic oxidation of C3H8. Results demonstrated that abundant low-coordinated Co atoms on the Co3O4-SPS surface boost the activation of adsorbed oxygen and enhance the catalytic activity. Moreover, Co3O4-SPS has better surface metal properties, which is beneficial to electron transfer between the catalyst surface and the reactant molecules, promoting the interaction between C3H8 molecules and dissociated O atoms and facilitating the activation of C-H bonds. Due to these, Co3O4-SPS harvests a prominent performance for C3H8 destruction, 100% of which decomposed at 165 °C (apparent activation energy of 49.4 kJ mol-1), much better than the bulk Co3O4 (450 °C and 126.9 kJ mol-1) and typical noble metal catalysts. Moreover, Co3O4-SPS also has excellent thermal stability and water resistance. This study deepens the atomic-level insights into the catalytic capacity of Co3O4-SPS in light alkane purification and provides references for designing efficacious catalysts for thermocatalytic oxidation reactions.

Size transformation of Au nanoclusters for enhanced photocatalytic hydrogen generation: Interaction behavior at nanocluster/semiconductor interface.

Recently, atomically precise metal nanoclusters (NCs) become a new class of photosensitizer for light energy conversion in metal-cluster-sensitized semiconductor (MCSS) system. However, fundamental understanding for the suitable combination of NCs and semiconductor is still unclear. Aside from aspects of light harvesting, energy level alignment and catalytic activity, interfacial interaction behavior at NCs/semiconductor interface is also crucial due to its important influence in charge transportation. In this work, the interface interaction between Au NCs and TiO2 is examined by precise transformation of Au NCs from Au22(SG)18 to Au18(SG)14, as well as its effect on photocatalytic hydrogen production activity. From the optical, charge transport and solid-states spectroscopy analyses, it is able to display that precisely tuning the number of core atoms from Au22(SG)18 to Au18(SG)14 results in the strong interface interaction between Au NCs and TiO2, reflecting in high difference of work function and modified surface band bending of TiO2, therefore promoting the injection of electrons from NCs to TiO2 and reducing interfacial charges recombination. As a result, Au18(SG)14/TiO2 shows higher hydrogen generation rate than Au22(SG)18/TiO2 under light irradiation. This work would provide new insights into rational combination of metal NCs with semiconductor and highlights the overlooked effect of interfacial interaction behavior on light energy conversion.

Visible-UVC upconversion polymer films for prevention of microbial infection.

Bacterial infections caused by the growth and reproduction of pathogenic bacteria on wounds are one of the main reasons that hinder wound healing. Antibacterial wound dressings protect wounds from bacterial infections. Herein, we developed a polymeric antibacterial composite film using polyvinyl alcohol (PVA) and sodium alginate (SA) as the substrate. The film used praseodymium-doped yttrium orthosilicate (Y2SiO5: Pr3+, YSO-Pr) to convert visible light into short-wavelength ultraviolet light (UVC) to kill bacteria. The YSO-Pr/PVA/SA showed upconversion luminescence in photoluminescence spectrometry tests, and the emitted UVC inhibited Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria in antibacterial tests. In vivo animal tests showed that YSO-Pr/PVA/SA is effective and safe for inhibiting bacteria in real wounds. The in vitro cytotoxicity test further confirmed the good biocompatibility of the antibacterial film. In addition, YSO-Pr/PVA/SA exhibited sufficient tensile strength. Overall, this study demonstrates the potential of upconversion materials for use in medical dressings.

Vis-UV Upconverting bacteriostatic hydrophobic bacterial cellulose film for personal protective masks.

Masks are key to personal protection and their bacteriostatic properties, which are generally overlooked, should be maximized. Towards this goal, a YPS-Pr-Li/BC upconversion antibacterial composite film was prepared by mixing upconversion powder with bacterial cellulose (BC) using a vacuum assisted method. When combined with the low surface energy of stearic acid (STA), the resulting YPS-Pr-Li/BC/STA film had an improved hydrophobic surface. The developed film was characterized by FT-IR, SEM, XRD, and fluorescence spectrophotometry. The results showed that the composite film was successfully prepared and had ultraviolet, visible upconversion luminescence. The bacteriostatic experiments showed that the material had excellent bacteriostatic performance against E. coli and S. aureus under visible light, with a bacteriostatic rate reaching 99 %. The in-vitro cytotoxicity tests showed that YPS-Pr-Li/BC/STA had excellent biocompatibility and could be used in personal protective clothing with close contact with human skin.

Modulating the Electronic Metal-Support Interactions in Single-Atom Pt1 -CuO Catalyst for Boosting Acetone Oxidation.

The development of highly active single-atom catalysts (SACs) and identifying their intrinsic active sites in oxidizing industrial hazardous hydrocarbons are challenging prospects. Tuning the electronic metal-support interactions (EMSIs) is valid for modulating the catalytic performance of SACs. We propose that the modulation of the EMSIs in a Pt1 -CuO SAC significantly promotes the activity of the catalyst in acetone oxidation. The EMSIs promote charge redistribution through the unified Pt-O-Cu moieties, which modulates the d-band structure of atomic Pt sites, and strengthens the adsorption and activation of reactants. The positively charged Pt atoms are superior for activating acetone at low temperatures, and the stretched Cu-O bonds facilitate the activation of lattice oxygen atoms to participate in subsequent oxidation. We believe that this work will guide researchers to engineer efficient SACs for application in hydrocarbon oxidation reactions.

Bacteriostatic activity and cytotoxicity of bacterial cellulose-chitosan film loaded with in-situ synthesized silver nanoparticles.

Bacterial infections on open wounds have always been a threat to human health. Herein, we prepared a silver (Ag)-polydopamine (PDA)/bacterial cellulose (BC)-chitosan (CTS) film using biological self-generation and in situ reduction. CTS was added to culture medium to allow BC to intertwine with CTS during film formation. Silver nitrate was reduced in situ to Ag nanoparticles under ultraviolet irradiation, and the nanoparticles were well dispersed in the BC-CTS film with the help of PDA, which worked synergistically with the CTS. The Ag-PDA/BC-CTS film was enriched in functional groups, and it had good tensile and swelling properties. The inhibition film demonstrated broad-spectrum inhibition of Gram-positive and Gram-negative bacteria, and this inhibition was maintained at more than 80% after 48 h of continuous use. The good biocompatibility of the film was verified using NIH3T3 fibroblasts. The results suggested that the Ag-PDA/BC-CTS film inhibited the growth of harmful bacteria while having little effect on healthy cells.

Achieving acetone efficient deep decomposition by strengthening reactants adsorption and activation over difunctional Au(OH)Kx/hierarchical MFI catalyst.

Realizing the simultaneous adsorption and activation of O2 and reactants over supported noble metal catalysts is crucial for the oxidation of organic hydrocarbons. Herein, we report a facile one-step ethylene glycol reduction method to synthesize difunctional Au(OH)Kx sites, which were anchored on a hierarchical hollow MFI support and adopted for acetone decomposition. The alkali ion-associated adjacent surface hydroxyl groups were coordinated with Au nanoparticles, resulting in partially oxidized Au1+ sites with improved dispersion. The results obtained from exclusive ex situ and in situ experiments illustrated that the proper content of K and hydroxyl groups significantly enhanced the adsorption of surface O2 and acetone molecules around the Au sites simultaneously, whereas the excess K species inhibited the catalytic performance by blocking the pore structure and decreasing the acidity of catalysts. The Au(OH)K0.7/h-MFI catalyst exhibited the highest efficiency for acetone oxidation, over which 1500 ppm acetone can be completely oxidized at just 280 °C with an extremely low activation energy of 32.5 kJ mol-1. The carbonate species were detected as the main intermediates during acetone decomposition over the difunctional Au(OH)Kx sites through a Langmuir - Hinshelwood (L - H) mechanism. This finding paves the way for designing and constructing efficient functional active sites for the complete oxidation of hydrocarbons.

Rapid degradation of dimethoate and simultaneous removal of total phosphorus by acid-activated Fe(VI) under simulated sunlight.

Ferrate (Fe(VI)) is usually effective for oxidizing a variety of organic pollutants within a few seconds, but some recalcitrant asorganophosphorus pesticides such as dimethoate require higher dose of Fe(VI) and inorganic phosphorus produced by mineralization is difficult to remove. In this study, acid-activated ferrate (Fe(VI)) was firstly used to degrade organophosphorus pesticides dimethoate and simultaneously remove total phosphorus (TP) from solution under simulated sunlight. At a Fe(VI):dimethoate molar radio of 15:1, dimethoate was almost completely removed within 20 min and 47% of TP in the solution was removed by the reduction product of Fe(VI) within 240 min. Electron paramagnetic resonance (EPR) and terephthalic acid (TA) fluorescence experiments showed that •OH radicals were continuously generated in the system, and •OH formation pathway was proposed. Importantly, the involvement of •OH in acid-activated Fe(VI) process was confirmed for the first time by EPR. In the acid-activated Fe(VI)/simulated sunlight system, the removal of dimethoate and TP gradually increased with the decrement of activation pH, whereas the increase of molar ratio of Fe(VI):dimethoate enhanced the removal of dimethoate and TP. The addition of inorganic anions (HCO3- and NO2-) had obvious inhibitory effects on dimethoate and TP removal. Eight degradation products including O,O,S-trimethylphosphorothiate, omethoate and 2-S-methyl-(N-methyl) acetamide were determined by gas chromatography mass spectrometry (GC-MS) analysis, and two possible degradation pathways were proposed. The insights gained from this study open a new avenue to simultaneously degrade and remove organic contaminants.

Non-thermal plasma coupled with MOF-74 derived Mn-Co-Ni-O porous composite oxide for toluene efficient degradation.

A novel strategy for removal of toluene by non-thermal plasma (NTP) coupled with metal-organic frameworks (MOFs) derived catalyst was proposed in this work. The MOF-derived porous trimetallic oxide catalyst (MnCoNiOx, MCNO) was prepared by simple pyrolysis of a MOF-74(Mn-Co-Ni) precursor. We found that the MCNO material can well synergy with NTP in total decomposition of toluene owing to its high specific surface area, regular porous structure and excellent reducibility, which endow superior catalytic activity and CO2 selectivity of NTP-MCNO system compared to that of NTP-MnOx, NTP-CoOx and NTP-NiOx. For instance, the toluene degradation efficiency can reach up to 75.7% in NTP-MCNO system with a low specific input energy of 101 J/L, much higher than that of NTP-MnOx (59.3%), NTP-CoOx (70.9%), NTP-NiOx (65.0%) and NTP alone (42.9%). Moreover, the formed ozone (O3) can be well-controlled by the NTP-MCNO system due to the spinel-type oxides (MCNO) derived from MOF could generate more open-formwork structure and improve the mobility of oxygen. The results of this work would shed light on rational design and preparation of spinel-type oxides for oxidation applications, which provides guidance for further improvement of plasma-catalysis system.

Chemical Vapor Deposition Growth of High Crystallinity Sb2 Se3 Nanowire with Strong Anisotropy for Near-Infrared Photodetectors.

Low-dimensional semiconductors have attracted considerable attention due to their unique structures and remarkable properties, which makes them promising materials for a wide range of applications related to electronics and optoelectronics. Herein, the preparation of 1D Sb2 Se3 nanowires (NWs) with high crystal quality via chemical vapor deposition growth is reported. The obtained Sb2 Se3 NWs have triangular prism morphology with aspect ratio range from 2 to 200, and three primary lattice orientations can be achieved on the sixfold symmetry mica substrate. Angle-resolved polarized Raman spectroscopy measurement reveals strong anisotropic properties of the Sb2 Se3 NWs, which is also developed to identify its crystal orientation. Furthermore, photodetectors based on Sb2 Se3 NW exhibit a wide spectral photoresponse range from visible to NIR (400-900 nm). Owing to the high crystallinity of Sb2 Se3 NW, the photodetector acquires a photocurrent on/off ratio of about 405, a responsivity of 5100 mA W-1 , and fast rise and fall times of about 32 and 5 ms, respectively. Additionally, owing to the anisotropic structure of Sb2 Se3 NW, the device exhibits polarization-dependent photoresponse. The high crystallinity and superior anisotropy of Sb2 Se3 NW, combined with controllable preparation endows it with great potential for constructing multifunctional optoelectronic devices.

Effect of Gd3+ , Bi3+ , or Sm3+ on luminescent properties of La2-x MgTiO6 :xEu3+ phosphors.

Single phase of Bi3+ , Gd3+ , Sm3+ and Eu3+ co-doped La2 MgTiO6 red phosphors were synthesized by high temperature solid-state method. The phase composition, morphology and fluorescent properties of the phosphors were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and fluorescence spectrometer. The La2-x MgTiO6 :xEu3+ phosphors can be excited by UV (396 nm) and blue (465 nm) light-emitting diode (LED) chips and show a strong red emitting with dominated wavelength at 615 nm. The optimum doping concentration of Eu3+ ion for La2 MgTiO6 is x = 0.5. The luminescent intensities of 5 D0  â†’ 7 F2 transition of Eu3+ in La1.5-y MgTiO6 :0.5Eu3+ , yBi3+ /Gd3+ /Sm3+ were 1.31 times, 1.32 times and 1.88 times that of La1.5 MgTiO6 :0.5Eu3+ at y = 0.08, 0.06, 0.06 for Bi3+ , Gd3+ , or Sm3+ sensitizer, respectively. The chromaticity coordinates of La1.44 MgTiO6 :0.5Eu3+ , 0.06Sm3+ , (0.6342, 0.3513) were very close to those of the National Television Standard Committee (NTSC) standard red light coordinates.

Selective Electrocatalytic Degradation of Odorous Mercaptans Derived from S-Au Bond Recongnition on a Dendritic Gold/Boron-Doped Diamond Composite Electrode.

To improve selectivity of electrocatalytic degradation of toxic, odorous mercaptans, the fractal-structured dendritic Au/BDD (boron-doped diamond) anode with molecular recognition is fabricated through a facile replacement method. SEM and TEM characterizations show that the gold dendrites are single crystals and have high population of the Au (111) facet. The distinctive structure endows the electrode with advantages of low resistivity, high active surface area, and prominent electrocatalytic activity. To evaluate selectivity, the dendritic Au/BDD is applied in degrading two groups of synthetic wastewater containing thiophenol/2-mercaptobenzimidazole (targets) and phenol/2-hydroxybenzimidazole (interferences), respectively. Results show that targets removals reach 91%/94%, while interferences removals are only 58%/48% in a short time. The corresponding degradation kinetic constants of targets are 3.25 times and 4.1 times that of interferences in the same group, demonstrating modification of dendritic gold on BDD could effectively enhance electrocatalytic target-selectivity. XPS and EXAFS further reveal that the selective electrocatalytic degradation derives from preferential recognition and fast adsorption to thiophenol depending on strong Au-S bond. The efficient, selective degradation is attributed to the synergetic effects between accumulative behavior and outstanding electrochemical performances. This work provides a new strategy for selective electrochemical degradation of contaminants for actual wastewater treatment.

Electrochemical characterization of poly-beryllon II modified carbon paste electrode and its application to selective determination of pyrocatechol and hydroquinone.

A poly-beryllon II film modified carbon paste electrode (PBL-II/CPE) has been constructed by electropolymerization method. Electrochemical characterization of the PBL-II/CPE was investigated by electrochemical impedance spectroscopy (EIS). The electrochemical behaviors of pyrocatechol (PC) and hydroquinone (HQ) were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) at the PBL-II/CPE in pH 7.0 phosphate buffer solution (PBS). The anodic peak currents were dramatically enhanced about threefold for PC at PBL-II/CPE. In addition, the modified electrode exhibits good selectivity toward selective determination of PC and HQ. By using DPV method, low detection limits of 0.8µM for PC and 1.0µM for HQ were obtained, respectively. Many outstanding advantages, such as wide linear ranges, low detection limits, excellent sensitivity, selectivity and stability confirmed that the PBL-II/CPE has promising analytical performance. Meanwhile, the electrode was successfully used for the determination of PC and HQ in local tap water sample and the results are satisfactory.

Three-dimensional homogeneous ferrite-carbon aerogel: one pot fabrication and enhanced electro-Fenton reactivity.

This work focuses on constructing a high catalytic activity cathode of an electro-Fenton system, to overcome the defects of low activity, poor stability, and intricate fabrication of supported catalysts. A series of ferrite-carbon aerogel (FCA) monoliths with different iron/carbon ratios was synthesized directly from metal-resin precursors accompanied by phase transformation. Self-doped ferrite nanocrystals and carbon matrix were formed synchronously via moderate condensation and sol-gel processes, leading to homogeneous texture. An optimal 5% ferric content FCA was composed of coin-like carbon nano-plate with continuous porous structure, and the ferric particles with diameters of dozens of nanometers were uniformly embedded into the carbon framework. The FCA exhibited good conductivity, high catalytic efficiency, and distinguished stability. When it was used as an electro-Fenton cathode, metalaxyl degradation results demonstrated that 98% TOC elimination was realized after 4 h, which was 1.5 times higher than that of the iron oxide supported electrode. It was attributed to self-doped Fe@Fe(2)O(3) ensuring Fe(II) as the mediator, maintaining high activity via reversibe oxidation and reduction by electron transfer among iron species with different valences. Meanwhile, an abundance of independent reaction microspaces were provided for every ferric crystal to in situ decompose electrogenerated H(2)O(2). Moreover, the possible catalytic mechanism was also proposed. The FCA was a promising candidate as potential cathode materials for high-performance electro-Fenton oxidation.

Selective photoelectrocatalytic degradation of recalcitrant contaminant driven by an n-P heterojunction nanoelectrode with molecular recognition ability.

With in situ molecular imprinting technique, a novel nanoelectrode (MI, n-P)-TiO(2) with n-P heterojunction and molecular recognition ability was fabricated by liquid phase deposition at low temperature. Using bisphenol A (BPA) as template, the spindle-like TiO(2) particles 40-80 nm in size compactly grew on the boron-doped diamond (BDD) substrate. Several spectroscopy measurements demonstrate that the BPA molecules were successfully imprinted on the TiO(2) matrix and numerous specific recognition sites to template were formed after calcination. The transient photocurrent response experiments have confirmed that the (MI, n-P)-TiO(2) nanoelectrode displays outstanding photoelectrocatalytic (PEC) activity and selectivity. The (MI, n-P)-TiO(2) is further employed in degrading the mixture containing BPA and interference 2-naphthol (2-NP). After 2 h, BPA removal reaches 97%, and corresponding kinetic constant is 1.76 h(-1), which is 4.6 times that of 2-NP removal even if 2-NP is much more concentrated. On the electrode without molecular imprint, the removal rate constants of BPA and 2-NP approximately equal, only about 0.5 h(-1). The results indicate that selective PEC oxidation can be realized readily on the (MI, n-P)-TiO(2) nanoelectrode due to the synergetic effects including strong recognition adsorption, formation of n-P heteojunction, and external electrostatic field. The effect of formation of n-P heterojunction on the enhanced PEC performances is also discussed.