Surface Oxidation Research Articles

THE INFLUENCE OF ABUTMENT SURFACE TREATMENT ON PULL-OFF BOND STRENGTH BETWEEN (5)YTTRIA STABILIZED ZIRCONIA CROWN AND TITANIUM IMPLANT ABUTMENT

ABSTRACT Aim: The objective of this research was to evaluate the effect of mechanical method and energetic method of surface treatments for Ti-abutment base (Ti-Base, Dentium/Korea) on the pull-off bond strength with (5)Y-TZP crown. Materials and Methods: : Forty titanium implant abutments were used in this study and randomly assigned to four groups (n = 10 for each group) according surface treatment methods of titanium abutment: group (1) act as control without surface treatment for Ti-abutment, group (2) bur surface treatment of Ti-abutment, group (3) sandblast (50-µm aluminum oxide) surface treatment for Ti-abutment, group (4) plasma surface treatment for Ti-abutment. Then, forty implant analogs were placed in the center of acrylic mold. After that abutment was tightened on the each analog with (35 N/cm) torque . Forty (5)Y-TZP crowns fabricated by CAD/CAM system that had special design with occlusal O-hole cemented to all abutments using Allcem dual-cure resin cement. All specimens were then subjected to thermos-cycling with (5000) cycles. With a universal testing machine record pull-off bond strength for all samples, Collected data were analyzed using a one-way analysis of variance at a significance level of (p < 0.01) . Results:, The bur treated abutment (group 2) group showed the highest bond strength values, followed by sandblast treated abutment (group 3) and plasma treated abutment (group 4). Control group was the lowest value of tensile strength. Conclusion: Surface treatments of Ti-abutment had observed effect on pull-off (tensile bond strength) between Ti-abutment and (5)Y-TZP crown Bur and sandblast cause roughness of surface and increase bond strength , plasma cause reactive surface for increasing tensile bond strength.

Oxidizing methanol at cubic-hexagonal junction of NiO-ZnO at low onset potential

A bimetallic, low-cost electrocatalyst consisting of non-noble nickel (Ni) and zinc (Zn) metal was synthesized for the effective oxidation of methanol (CH3OH). The formation of cubic NiO (nickel oxide) and hexagonal ZnO (zinc oxide) was confirmed by various spectrophotometric analyses. NiO-ZnO modified with -COOH functionalized MWCNT, NiO-ZnO-f-MWCNT exhibited significant methanol oxidation reaction (MOR) activity without any substantial oxygen evolution reaction (OER). At a lower onset potential value of 1.33 V versus RHE (reversible hydrogen electrode), the catalyst NiO-ZnO-f-MWCNT demonstrated a high current density of 3.88 × 103 Am-2 in 1 M KOH and 1 M CH3OH. The catalyst NiO-ZnO-f-MWCNT, with the lowest Tafel slope value compared to the other synthesized catalysts, was found to be stable without significantly losing current density, for about 500 cycles and 25000s. Density functional theory (DFT) calculation unveiled that all the steps involved during the interaction of CH3OH and the catalyst surface for oxidation of CH3OH were exergonic indicating a thermodynamically feasible and favourable process of MOR. The electrocatalytic activity was found to be dependent on the concentration of both Ni and Zn. An increase in Ni concentration hampered the MOR by favouring the OER.

Determining the influence of relative humidity on the working parameters of a gas sensor based on zinc oxide

This paper investigates the dependence of operating parameters of a gas sensor based on zinc oxide obtained by the method of direct current magnetron sputtering. The production of gas sensor films was carried out using a VUP-5M vacuum unit with an original material-saving magnetron. The study of the dependence of the working parameters of the gas sensor was carried out under standard conditions. It was found that with increasing humidity, the electrical resistance of the gas sensor decreases and, accordingly, the sensitivity to the target gas decreases. A significant reaction of the gas sensor to an increase in humidity was observed in the range of 65–80 % relative humidity. The mechanism of influence of relative humidity on the sensitivity of a gas sensor based on ZnO was investigated. The change in resistance of the gas sensor is caused by trapped electrons on adsorbed oxygen molecules on the surface of the sensitive layer. The capture of electrons from the conduction zone leads to bending of the conduction zone and an increase in the space charge zone, respectively, to a change in the resistance of the sensitive layer of the gas sensor. In the atmosphere, when O2 molecules are adsorbed on the ZnO surface, they remove an electron from the conduction band. The reaction of oxygen adsorbed on the ZnO surface with reducing gases and the replacement of adsorbed oxygen with other molecules changes the bending of the conduction band and reduces the area of space charge. Adsorption of water on the surface of zinc oxide occurs according to the dissociation mechanism, which consists in the adsorption of steam molecules or hydroxyl groups with the subsequent displacement of previously adsorbed oxygen and free electrons and, accordingly, leads to a decrease in the sensitivity of the gas sensor. In addition, the adsorption of water vapor (H2O) molecules leads to less chemisorption of oxygen species on the ZnO surface due to the reduction of the surface area, which is responsible for the sensor response. Approaches to reduce the influence of relative humidity on the sensitivity of a gas sensor based on zinc oxide have been proposed

Advanced supercapacitor electrodes: Synthesis and electrochemical characterization of graphene oxide-bismuth metal-organic framework composites for superior performance

The primary requirements for a viable supercapacitor electrode material are increased energy density, high specific capacitance, and excellent cycle stability. The desired outcome may be attained by combining diverse active materials. In this research, two Bi-MOFs with 1,4-benzenetdicarboxylic (H2BDC) and 1,3,5-benzenetricarboxylic (H3BTC) organic linkers were synthesized by facile solvothermal method and bonded on the surface of graphene oxide to produce FGO-Bi(BTC) and FGO-Bi(BDC) composites. The electrochemical characteristics of the two electroactive compounds were evaluated by GCD, CV, and EIS tests in a three-electrode setup. Comparative electrochemical analyses demonstrated that the composites exhibit remarkable performance with reduced charge transfer resistance. In the three-electrode configuration, FGO-Bi(BDC) and FGO-Bi(BTC) exhibited specific capacitances of 559 and 422 F g-1 at 1 A g-1, respectively. After conducting 10,000 cycles of charge and discharge at 8 A g-1, the FGO-Bi(BDC) and FGO-Bi(BTC) electrodes exhibited impressive retention rates of 97.6% and 95.64% for their initial specific capacitance (Cs). Notably, the three-electrode system's results indicated superior electrochemical performance of the FGO-Bi(BDC) electrode over the FGO-Bi(BTC) electrode. This superiority is attributed to the FGO-Bi(BDC)'s larger specific surface area (SSA) and reduced oxygen concentration. For a more practical assessment, the FGO-Bi(BDC) composite was selected for evaluation in the two-electrode system. The FGO-Bi(BDC)//FGO-Bi(BDC) two-electrode system demonstrated a cyclic stability of 94.2% over 10,000 cycles, attaining a substantial Cs of 295 F g-1 at 1 A g-1. Moreover, it accomplished a power density of 750 W kg-1 and an energy density of 34.61 Wh kg-1, emphasizing the exceptional electrochemical attributes that position the FGO-Bi(BDC) composite as a promising electrode material for supercapacitors.

Copper foil microforming through underwater laser oblique impact

Laser-induced cavitation impact forming is a high-speed forming process that employs a high-energy laser to produce cavitation in a liquid and act on the workpiece. When the laser is irradiated vertically to the workpiece surface through the guide hole, oxidation occurs on the produced workpiece's surface, affecting the surface quality. Laser-induced cavitation oblique impact workpiece formation is proposed in this paper. The surface quality of the workpiece created at various angles is investigated by adjusting the angle between the laser and the guide hole. A finite element model (FEM) was employed to simulate the temperature change and collapse speed of laser-induced cavitation, and a hydrophone was utilized to measure the impact pressure of laser-induced cavitation under various guide holes. The variations in forming depth and surface quality of the workpiece caused by laser-induced cavitation oblique impact were investigated experimentally. The experimental results show that as the angle between the laser and the guide hole increases from 0° to 90°, the width of the oxidized area on the surface of the formed micro-groove decreases from 513 μm to 0 μm, the forming depth of the micro-groove decreases from 80 μm to 20 μm, and the surface roughness of formed parts decreases from 2.93 μm to 0.56 μm. The oxidation of the formed workpiece surface during the oblique laser impact is primarily caused by the laser irradiation, according to the analysis of the surface oxidation mechanism of the formed micro-grooves. When the angle between the laser and the guide hole is 60°, all of the heat emitted by the laser is focused to the guide hole's inner surface. The angle between the laser and the pilot hole was set to 60° in the experiment, and the micro-groove structure was generated by three impacts, with the thickness distribution of the formed groove investigated. The results demonstrate that the largest thinning of the micro-groove cross-section occurs at the mold's entry and the bottom of the micro-groove, with thinning rates of 20 % and 15 %, respectively.

Impact of aging of primary and secondary polystyrene nanoplastics on the transmission of antibiotic resistance genes in anaerobic digestion

Sewage sludge is a significant reservoir of nano/microplastics (NPs/MPs) and antibiotic resistance genes (ARGs). Research has revealed that NPs/MPs may exert an inhibitory effect on anaerobic digestion (AD) of sludge. Moreover, NPs/MPs can influence microbial community diversity and composition, potentially increasing ARGs dissemination. The morphological changes to NPs/MPs surface due to aging contribute to modifying hydrophobic properties. To date, there is limited comprehension regarding how various surface properties of NPs influence ARGs dissemination during AD. This study investigated the impact of primary aged/non-aged and secondary aged/non-aged polystyrene nanoplastics (PSNPs) on ARGs and mobile genetic elements (MGEs) propagation during AD. The findings indicated that the UV-aging process resulted in surface oxidation and distinct morphological characteristics in both primary and secondary PSNPs, while the surface oxidation effect was more pronounced in the secondary aged PSNPs. High concentrations (150 μg/L) of primary and secondary PSNPs inhibited methane production, with secondary PSNPs causing greater inhibition by 16 to 20 % compared to control. In contrast, low concentration (25 μg/L) had negligible or slightly positive effects on methane production. PSNPs at 150 μg/L reduced total VFA concentration, indicating an inhibitory effect on the fermentation step in the AD process. Primary and secondary PSNPs exhibited changes in EPS characteristics. ARGs abundance was enriched in reactors amended with PSNPs, with the highest abundance of 8.54 × 105 copies/g sludge observed in the secondary aged PSNPs (150 μg/L) reactor. Reactors exposed to aged PSNPs exhibited a relatively higher abundance of ARGs compared to reactors exposed to non-aged PSNPs. Exposure to PSNPs increased the microbial community diversity within the digesters and triggered the enrichment of Comamonadaceae and Syntrophaceae, belonging to Proteobacteria phylum. On the other hand, archaeal communities tended to shift towards hydrogenotrophic methanogens in PSNPs reactors. The correlation analysis showed that Comamonadaceae were positively correlated with the majority of ARGs and intl1. A positive correlation was observed between MGEs and most ARGs, suggesting that the increased proliferation of ARGs under PSNPs exposure may be linked to the abundance of MGEs, which in turn promotes the growth of hosts carrying ARGs. These findings suggest that aged and non-aged NPs could substantially impact the spread of ARGs and MGEs, which also led to notable alterations in the composition of the microbial community. Overall, this study provides valuable insights into the multifaceted impacts of PSNPs with various characteristics on AD processes, microbial communities, and ARGs proliferation, highlighting the urgent need for comprehensive assessments of NPs pollutants in the environment.

Size- and Shape-Dependent Interactions of Lipid-Coated Silver Nanoparticles: An Improved Mechanistic Understanding through Model Cell Membranes and In Vivo Toxicity.

The widespread use of silver nanoparticles (AgNPs) in various applications and industries has brought to light the need for understanding the complex relationship between the physicochemical properties (shape, size, charge, and surface chemistry) of AgNPs that affect their ability to enter cells and cause toxicity. To evaluate their toxicological outcomes, this study systematically analyzed a series of homogeneous hybrid lipid-coated AgNPs spanning sizes from 5 to 100 nm with diverse shapes (spheres, triangles, and cubes). The hybrid lipid membrane comprises hydrogenated phosphatidylcholine (HPC), sodium oleate (SOA), and hexanethiol (HT), which shield the AgNP surface from surface oxidation and toxic Ag+ ion release to minimize its contribution to toxicity. To reduce any significant effects by surface chemistry, the HPC, SOA, and HT membrane composition ratio was kept constant, and the AgNPs were assessed using embryonic zebrafish (Danio rerio). While a direct comparison cannot be drawn due to the lack of complementary sizes below 40 nm for triangular plates and cubes due to synthetic challenges, significant mortality was observed for spherical AgNPs (AgNSs) of 5, 20, 40, and 60 nm at 120 h postfertilization at concentrations ≥6 mg Ag/L. In contrast, the 10, 80, and 100 nm AgNSs, 40, 70, and 100 nm triangular plate AgNPs (AgNPLs), and 55, 75, and 100 nm cubic AgNPs (AgNCs) showed no significant mortality at 5 days postfertilization following exposure to AgNPs at concentrations up to 12 mg Ag/L. With constant surface chemistry on the AgNPs, size is the dominant factor driving toxicological responses, with smaller nanoparticles (5 to 60 nm) being the most toxic. Larger AgNSs, AgNCs, and AgNPLs from 75 to 100 nm do not show any evidence of toxicity. However, when closely examining sizes between 40 and 60 nm for AgNSs, AgNCs, and AgNPLs, there is evidence that discriminates shape as a driver of toxicity since sublethal responses generally were observed to follow a pattern, suggesting toxicity is most significant for AgNSs followed by AgNPLs and then AgNCs, which is the least toxic. Sum frequency generation vibrational spectroscopy showed that irrespective of size or shape, all hybrid lipid-coated AgNPs interact with membrane surfaces and "snorkel" between phases into the lipid monolayer with minimal energetic cost. These findings decisively demonstrate that not only smaller AgNPs but also the shape of the AgNPs influences their biological compatibility.

Oxide coated nickel powder as support for platinum(0) nanoparticles: Magnetically separable catalysts for hydrogen generation from the hydrolysis of ammonia borane

We report the development of a novel method for the preparation of magnetically separable platinum nanoparticles. Magnetic nickel nanopowder is initially synthesized in a radiofrequency plasma reactor where in-line passivation was carried out with oxygen gas, resulting in the formation of nickel oxidecoated nickel particles. Following this, platinum nanoparticles are deposited onto the surface of the oxidecoated nickel nanopowder, forming Pt0/Ni@NiO nanocatalysts for the hydrolytic dehydrogenation of ammonia borane. The Pt0/Ni@NiO nanoparticles, containing 0.24 % wt. Pt, exhibit remarkable catalytic activity in the hydrolytic dehydrogenation of ammonia borane, with a turnover frequency of 468 (mol H2)×(mol Pt)−1×min−1 for releasing 3 equivalent H2 gas per mole of ammonia borane from its hydrolysis at 25 ºC. This heightened catalytic activity of Pt0/Ni@NiO nanoparticles is attributed to the favorable metal-support interaction between the platinum(0) nanoparticles and oxide surface, namely the bonding of platinum to the oxide surface, as elucidated by the XPS analysis. More importantly, Pt0/Ni@NiO nanoparticles can be separated from the reaction solution by using an external magnet.

Rolling Element Bearing Damage in the Presence of Applied Electric Current

Modern wind turbines and battery electric vehicles have bearings in close proximity to electrical generators, motors, and inverters. These systems have motivated new research focused on damage mechanisms associated with low- and high-level electric currents in rolling element bearings. This work presents a study on the influence of applied electric current and lubricant selection on bearing surface damage. Direct current was applied to a rotating tapered roller bearing with axial load and oil lubrication. Tests were conducted with various levels of applied current and two different oils (additized and non-additized). Micropitting, white etching cracking (WEC), and the formation of a surface white layer were investigated using both optical microscopy and scanning electron microscopy. Some of the tested bearings had black oxide surface treatment on their rollers and raceways. The black oxide was evaluated with regard to the prevention of the WEC damage mode. The occurrence of the described damage modes depended on the type of oil used and the application of electric current. Higher electric currents increased bearing surface damage in these tests.

Corrosion Behavior of 20G and TP347H in Molten LiCl-NaCl-KCl Salt.

The corrosion behavior of 20G and TP347H materials was investigated in molten LiCl-NaCl-KCl salt. The corrosion rates of these materials in molten chloride salt are high and are strongly affected by the alloying surface oxide formation. The 20G shows uniform surface corrosion with almost no protective oxide formation on the surface. In contrast, the austenitic steel TP347H exhibits better corrosion resistance in molten chloride salts due to its high Cr content. Owing to the highly corrosive nature of molten chloride salts, the Cl- in molten salt could react with oxides and alloy, inducing intergranular corrosion of austenitic steel in molten chloride salt environments.

Redox behavior of unsubstituted cobalt phthalocyanine in nanostructured Langmuir-Schaefer films

Although the properties of unsubstituted metal tetrapyrroles in solutions have received attention in numerous work, the physico-chemistry of their thin films remains poorly investigated. In this work, we constructed thin films of unsubstituted cobalt phthalocyanine on the surface of quartz plates and indium tin oxide (ITO) electrodes using the Langmuir-Schaefer (LS) and drop casting techniques. In LS films, CoPc species are involved in strong intermolecular interactions, which result in formation of CoPc nanostructures and prominent changes in the ultraviolet-visible spectrum. Electrochemical reduction of CoPc in LS films at −0.9 V (versus silver chloride electrode) results in formation of Co(I) species. In contrast to the highly reactive nature of Co(I)Pc in solution, these species generated in thin films are relatively resistant to dioxygen due to the dense packing of CoPc units. These findings can further the development of CoPc-based resistive sensors utilizing not only common Co(II), but also Co(I) species, which may possess different sensitivity toward analytes.

Spatiotemporal variability of surface ozone and associated meteorological conditions over the Arabian Peninsula

This study investigates the spatiotemporal variability of surface ozone (O3) over the Arabian Peninsula (AP) between 2005 and 2019, focusing on the Arabian Gulf (AG). The analysis explores the relationship between surface O3 data from the Copernicus Atmosphere Monitoring Service (CAMS) with boundary layer height (BLH), 2 m temperature (T2M), downward ultraviolet radiation at the surface (UVB), and 10 m wind speed (WS) and direction from the fifth generation European Centre for Medium-Range Weather Forecasts (ECMWF) atmospheric reanalysis (ERA5). Also, the study considers Carbon Monoxide (CO) and Nitrogen Oxides (NOx) surface emissions from the Tropospheric Chemical Reanalysis version 2 (TCR-2). Furthermore, it investigates the impact of El Niño Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) on surface O3 variations on a seasonal scale. Surface O3 observations from 15 ground-based stations across the AP were used to evaluate CAMS-O3, showing a good agreement between CAMS and the observations. The analysis of mean diurnal variations of CAMS-O3 and ERA5 reveals that surface O3 is highest over the eastern parts of the AP, mainly the AG, peaking during summer, followed by spring, fall, and winter. This seasonal cycle is also observed, to a large degree, in BLH, T2M, UVB, and WS. The results also reveal insignificant correlation between surface O3 and ENSO, but stronger correlation with IOD, especially over the AG during summer and fall. The analysis indicates that elevated T2M and UVB during daytime and elevated BLH during nighttime are significant contributors to increased levels of O3 over the AG.

Microstructural evolution and thermal stability of Al–Zn–Mg–Cu–Si–Zr alloy fabricated via spark plasma sintering

We investigated the microstructural evolution and thermal stability of Al–Zn–Mg–Cu–Si–Zr alloy fabricated via high-energy ball milling (HEBM), spark plasma sintering (SPS), and heat treatment at 500 °C. HEBM induces the Al2O3 surface oxide to penetrate the powder interior, and the surface oxide is transformed into MgO particles along the grain boundaries during the sintering process, depleting the Mg solid solution in the matrix. HEBM caused the formation of Mg-free phases and accelerated the transformation of Zr into the Si2Zr phase. Heat treatment promoted the transformation of Zr to the Si2Zr phase in the Zr/Si2Zr coupled particles and caused the coarsening of the secondary phase. The MgO particles present along the grain boundaries suppressed the grain growth of the sintered alloy until fine MgO was transformed into coarse MgAl2O4. The microhardness of the sintered alloy was significantly increased by the application of HEBM, mainly owing to strengthening by grain refinement and oxide dispersion. The Al–Zn–Mg–Cu–Si–Zr sintered alloy maintained high microhardness values even after heat treatment at 500 °C for 168 h, indicating the excellent thermal stability of the alloy compared to the Zr-free Al–Zn–Mg–Cu–Si alloy.

Polystyrene microplastics facilitate formation of refractory dissolved organic matter and reduce CO2 emissions

Microplastics, as a type of anthropogenic pollution in aquatic ecosystems, affect the carbon cycle of organic matter. Although some studies have investigated the effects of microplastics on dissolved organic matter (DOM), the impact of alterations in the chemical properties of microplastics on refractory DOM and carbon release remains unclear. Here, we observed that microplastic treatments (e.g., polystyrene, PS) altered the composition and function of microbial community, notably increasing the abundance of microbial families involved in consuming easily degradable organic matter. During the process in which microbial community decomposed organic matter into DOM, PS underwent surface oxidation. The oxidized PS aggregated with DOM and microorganisms through electrostatic interactions and chemical bonds. Moreover, these interactions between oxidized PS and microbial community affect the utilization of organic matter, resulting in a significant decrease in CO2 emissions. Specifically, total CO2 emissions decreased by approximately 23.76 % with 0.1 mg/L PS treatment and by 44.97 % with 10 mg/L PS treatment compared to those in PS-free treatments over the entire reaction. These findings underscored the significance of the chemical properties of PS in the interactions among DOM and microorganisms, emphasizing the potential impact of PS microplastics on the carbon cycle in ecosystems.

Insights into Electrochemical CO2 Reduction on Metallic and Oxidized Tin Using Grand-Canonical DFT and In Situ ATR-SEIRA Spectroscopy.

Electrochemical CO2 reduction (CO2R) to formate is an attractive carbon emissions mitigation strategy due to the existing market and attractive price for formic acid. Tin is an effective electrocatalyst for CO2R to formate, but the underlying reaction mechanism and whether the active phase of tin is metallic or oxidized during reduction is openly debated. In this report, we used grand-canonical density functional theory and attenuated total reflection surface-enhanced infrared absorption spectroscopy to identify differences in the vibrational signatures of surface species during CO2R on fully metallic and oxidized tin surfaces. Our results show that CO2R is feasible on both metallic and oxidized tin. We propose that the key difference between each surface termination is that CO2R catalyzed by metallic tin surfaces is limited by the electrochemical activation of CO2, whereas CO2R catalyzed by oxidized tin surfaces is limited by the slow reductive desorption of formate. While the exact degree of oxidation of tin surfaces during CO2R is unlikely to be either fully metallic or fully oxidized, this study highlights the limiting behavior of these two surfaces and lays out the key features of each that our results predict will promote rapid CO2R catalysis. Additionally, we highlight the power of integrating high-fidelity quantum mechanical modeling and spectroscopic measurements to elucidate intricate electrocatalytic reaction pathways.

Efficient Air-Processed MA-Free Perovskite Solar Cells by SH-Based Silane Interface Modification.

Air-processed perovskite solar cells (PSCs) with high photoelectric conversion efficiency (PCE) can not only further reduce the production cost but also promote its industrialization. During the preparation of the PSCs in ambient air, the contact of the buried interface not only affects the crystallization of the perovskite film but also affects the interface carrier transport, which is directly related to the performance of the device. Here, we optimize the buried interface by introducing 3-mercaptopropyltrimethoxysilane (MPTMS, (CH3O)3Si(CH2)3SH) on the nickel oxide (NiOx) surface. The crystallization of the perovskite film is improved by enhancing surface hydrophobicity; besides, the SH-based functional group of MPTMS passivates the uncoordinated lead at the interface, which effectively reduces the defects at the bottom interface of perovskite and inhibits the nonradiative recombination at the interface. Moreover, the energy level between the NiOx layer and the perovskite layer is better matched. Based on multiple functions of MPTMS modification, the open circuit voltage of the device is obviously improved, and efficient air-processed methylamine-free (MA-free) PSCs are realized with PCE reaching 21.0%. The device still maintains the initial PCE of 85% after 1000 h aging in the glovebox. This work highlights interface modification in air-processed MA-free PSCs to promote the industrialization of PSCs.

Epoxy-ended hyperbranched polymer-grafted graphene oxide for cold-mixed epoxy asphalt modification

ABSTRACT To improve the compatibility of asphalt-epoxy and mechanical properties of cold-mixed epoxy asphalt (CEA), epoxy-ended hyperbranched polymer (EHBP) was grafted on the surface of graphene oxide (GO) nanoplates to synthesize GOEHBP as a compatilizer. The chemical structures and micromorphology of GOEHBP were analysed through Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, thermo gravimetric analysis and transmission electron microscopy. The CEA modified by EHBP and GOEHBP was investigated by tensile test, dynamic thermomechanical analysis, viscosity test, fluorescence microscope experiment, FTIR analysis and XPS analysis. The results showed that the EHBP was successfully grafted onto the surface of GO via chemical reaction, and the GO was partially reduced. The mechanical properties of CEA modified by EHBP are obviously improved, and the elongation at break was increased by 74.5%. The glass transition temperature of CEA modified by GOEHBP was increased to 62.58°C. At high temperature (≥40°C), the E′ of CEA modified by GOEHBP was larger than that of the CEA, indicating that GOEHBP can improve the high-temperature deformation resistance of CEA. The addition of GOEHBP can improve the compatibility of asphalt-epoxy, thus improving the toughness of CEA.

Vacancy Ordering in Ultrathin Copper Oxide Films on Cu(111).

Oxide thin films grown on metal surfaces have wide applications in catalysis and beyond owing to their unique surface structures compared to their bulk counterparts. Despite extensive studies, the atomic structures of copper surface oxides on Cu(111), commonly referred to as "44" and "29", have remained elusive. In this work, we demonstrated an approach for the structural determination of oxide surfaces using element-specific scanning tunneling microscopy (STM) imaging enhanced by functionalized tips. This approach enabled us to resolve the atomic structures of "44" and "29" surface oxides, which were further corroborated by noncontact atomic force microscopy (nc-AFM) measurements and Monte Carlo (MC) simulations. The stoichiometry of the "44" and "29" frameworks was identified as Cu23O16 and Cu16O11, respectively. Contrary to the conventional hypothesis, we observed ordered Cu vacancies within the "44" structure manifesting as peanut-shaped cavities in the hexagonal lattice. Similarly, a combination of Cu and O vacancies within the "29" structure leads to bean-shaped cavities within the pentagonal lattice. Our study has thus resolved the decades-long controversy on the atomic structures of "44" and "29" surface oxides, advancing our understanding of copper oxidation processes and introducing a robust framework for the analysis of complex oxide surfaces.

Electrochemical Stability of MXenes in Water Based on Constant Potential AIMD Simulations.

MXene has been recently explored as promising electrocatalytic materials to accelerate the electrocatalytic process for hydrogen evolution, but their dynamic stability under electrochemical conditions remains elusive. Here we performed first-principles ab initio molecular dynamics calculations to reveal the electrochemical stability of Ti2CTx MXene in different aqueous environments. The results revealed the high vulnerability of the pure and vacancy-defected Ti2CO2 MXene towards water attack, leading to surface oxidation of MXene under neutral electrochemical conditions that formed adsorbed oxygen species to Ti and the dissociated proton in solution. The surface oxidation of Ti2CO2 could be prevented in the acid condition or in the neutral condition under the negative potential. Differently, the fully F- or OH-functionalized Ti2CF2 and Ti2C(OH)2 as well as the mixed functionalized Ti2C(O0.5OH0.5)2 and Ti2CO1.12F0.88 are highly stable under various electrochemical conditions, which can effectively prevent close contact between water molecules and surface Ti atoms via electronic repulsion or steric hindrance. These findings provide atomic level understanding of the aqueous stability of MXene and provide useful strategies to prevent degradation and achieve highly stable MXenes.

A comparative study of electrochemical stability and biocompatibility of TiN nanowires and thin films for neural-electrode application

Neural-electrode devices with adequate charge injection capacity, long operating lifetime and excellent biocompatibility with interfaced tissues are essential to treat chronic neurological disorders. The device's efficiency hinges on the electrochemical properties of the electrode material, prompting extensive research on diverse material surfaces. Here, we investigate the electrochemical stability and biocompatibility of titanium nitride (TiN) nanowires (NWs) synthesized previously through the novel plasma enhanced chemical vapor deposition (PECVD) utilizing lower temperature as compared to conventional methods. These TiN-NWs were compared with TiN thin films, shedding light on their respective performances. TiN-NWs electrode revealed far superior electrochemical stability over 1000 cycles, achieving a capacitance retention of 93 % as compared to 68 % to that of TiN film electrode, under ambient conditions with dissolved oxygen. Additionally, impedance of TiN-NWs showed almost no change with cycling as compared to the film electrode. Moreover, our in-vitro cell culture spanning 20 days exhibited excellent biocompatibility for both substrates. Interestingly, cell distribution on the NWs appeared more dispersed with fewer clusters, potentially facilitating controlled electrical stimulation. These findings not only highlights the potential use of TiN-NWs for chronic stimulation of neurons, but also shows that surface morphology has a potential effect in minimising surface oxidation and improving electrochemial performance of the material.