Interfacial Reaction Mechanism Research Articles

An energetic MOF-assistant confined expansion strategy to fabricate Fe-doped porous carbon beads for advanced oxidation processes: Interfacial reaction mechanism and biological toxicity

Porous carbon material catalysts derived from MOFs-based precursors are gradually being used extensively in advanced oxidation possesses. However, some of the existing problems such as hard to recovery and easy to secondary pollution still need to be solved. Here, a series of Fe-doped energetic metal–organic framework (EMOF)-derived porous carbon spheres (EMFexS) were obtained by the phase inversion route. EMOFs puffed up during pyrolysis at high temperatures to create large-sized hierarchically porous structure. The large specific surface area (483.4 m2/g) and high nitrogen content, and hierarchically porous structure endow EMFe0.2S with excellent catalytic performance to remove tetracycline removal efficiency. By activating peroxymonosulfate (PMS), it was found that the rate constant (k) in EMFe0.2S/PMS system was 0.058 min−1, which was 1.75, 1.56 and 1.52 times than that of EMFe0S/PMS system, EMFe0.1S/PMS system and EMFe0.25S/PMS system, respectively. Experiments and material characterization point that the existence of nitrogen and iron in the catalyst were the potential active sites. The continuous flow catalytic reaction and biological toxicity experiments were employed to evaluate practical application value. This study provides new insights into the preparation of microspheres for water treatment with the help of EMOF-assisted confined expansion strategy.

Enhanced SO2 adsorption performance on nitrogen-doped biochar: Insights from generalized two-dimensional correlation infrared spectroscopy

Nitrogen-doped biochar is considered as a renewable, cost-effective, and promising SO2 adsorbent. However, it is difficult to improve the physicochemical properties of biochar synergistically and clarify the adsorption mechanism. Therefore, in this study, a one-step high-temperature CO2-NH3 modification method was proposed for biochar to improve its SO2 adsorption, and the in situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (in situ DRIFTS) was used to reveal the interface reaction mechanism between SO2 and nitrogen-doped biochar. The results showed that when the modification temperature exceeded 700 °C, CO2 and NH3 exhibited significant thermal activation and nitrogen doping on biochar simultaneously. Under a modification temperature of 800 °C (BCAN-800), the microporous surface area and nitrogen content of modified biochar reached the highest value of 563.83 m2/g and 6.63 wt%. The SO2 adsorption capacities of BCAN-800 were up to 201.89 mg/g and 145.68 mg/g at 30 °C and 120 °C, respectively. The results of in situ DRIFTS showed that dimeric and bridge hydrogen bonds were the main SO2 adsorption sites on nitrogen-doped biochar at 30 °C. With the increase of adsorption temperature, nitrogen-containing groups as the main adsorption site could combine with SO2 to form sulfamide (60 °C), which eventually existed in a more stable form of SO42−/R-O-SO2-OR′ (120 °C).

Interfacial reaction in Al2O3 fiber reinforced TiAl matrix composite

Al2O3 short fiber (containing 28 vol.% SiO2) reinforced TiAl matrix composite was prepared by spark plasma sintering (SPS). The interfacial reaction mechanism was clarified by thermodynamic and kinetic analyses. The main interfacial phase was Ti5Si3, originated from Ti element of TiAl matrix and Si element of Al2O3 fiber. The activation energy of interfacial layer was 285.1 kJ/mol. In addition, the matrix around the interfacial region was composed of γ-TiAl phase due to the consumption of Ti element in the process of interfacial reaction. However, the formation of mullite phase occurred in the heat-treated Al2O3 fiber and as-sintered composite due to the chemical reaction between γ-Al2O3 and amorphous SiO2 phases.

Interfacial behavior and mechanism of brazed diamond with CeO2-added Ni-Cr filler alloy: a combined first-principles and experimental study

PurposeThis paper aims to investigate the effect and mechanism of O atom single doping, Ce and O atoms co-doping on the interfacial microscopic behavior of brazed Ni-Cr/diamond.Design/methodology/approachUsing first-principles calculations, the embedding energy, work of separation, interfacial energy and electronic structures of Ni-Cr-O/diamond and Ni-Cr-O-Ce/diamond interface models were calculated. Then, the effect of Ce and O co-doping was experimentally verified through brazed diamond with CeO2-added Ni-Cr filler alloy.FindingsThe results show that O single-doping reduces the interfacial bonding strength between Ni-Cr filler alloy and diamond but enhances its interfacial stability to some extent. However, the Ce and O co-doping simultaneously enhances the interfacial bonding strength and stability between Ni-Cr filler alloy and diamond. The in-situ formed Ce-O oxide at interface impedes the direct contact between diamond and Ni-Cr filler alloy, which weakens the catalytic effect of Ni element on diamond graphitization. It is experimentally found that the fine rod-shaped Cr3C2 and Cr7C3 carbides are generated on diamond surface brazed with CeO2-added Ni-Cr filler alloy. After grinding, the brazed diamond grits, brazed with CeO2-added Ni-Cr filler alloy, present few fracture and the percentage of intact diamond reaches 67.8%. Compared to pure Ni-Cr filler alloy, the brazed diamond with CeO2-added Ni-Cr filler alloy exhibit the better wear resistance and the slighter thermal damage.Originality/valueUsing first-principles calculations, the effect of Ce and O atoms co-doping on the brazed diamond with Ni-Cr filler alloy is investigated, and the calculation results are verified experimentally. Through the first-principles calculations, the interface behavior and reaction mechanism between diamond and filler alloy can be well disclosed, and the composition of filler alloy can be optimized, which will be beneficial for synergistically realizing the enhanced interface bonding and reduced thermal damage of brazed diamond.

Mechanisms of interfacial reactions between 316L stainless steel and MnO–SiO2 oxide during isothermal heating

Mechanisms of interfacial reactions between 316L stainless steel and MnO–SiO2 oxide during isothermal heating

Phase transfer mechanisms of fluorophore-labeled cell-penetrating peptide ε-poly-l-α-lysine at liquid|liquid interfaces

The transfer reaction of a novel cell-penetrating peptide, ε-poly-l-α-lysine (εPL) as a bacterial polycationic isopeptide, was investigated at the water|1,2-dichloroethane (DCE) interface. Spectroelectrochemical analysis elucidated the interfacial reaction mechanism of covalently carboxyfluorescein (FAM)-labeled εPL (FAM-εPL) in detail. FAM-εPL showed the concentration-dependent interfacial mechanisms in the positive potential region, i.e., the adsorption from the aqueous side of the interface was occurred at the low concentration of FAM-εPL, while the ion transfer across the interface accompanied by the adsorption process at the organic side proceeded further as the concentration increased. The facilitated ion transfer of FAM-εPL was observed at the biomimetic interface with a phospholipid layer. The transfer process of FAM-εPL was accelerated by the specific interaction at the aqueous side of the biomimetic interface, that is, the polar headgroup region of the phospholipid layer. The interfacial and membrane permeation mechanisms of εPL were elucidated through the spectroelectrochemical measurements by the fluorescent FAM modification and the phase transfer of a membrane impermeable FAM was also achieved by forming the conjugate with εPL.

Interfacial reaction mechanism and high temperature stability of heat-resistant steel and SiC under a vacuum environment

The physical and chemical stabilities of SiC and heat-resistant steel were assessed by the diffusion couple method under vacuum at 1200 °C, which is a commonly used condition in magnesium metallurgy. High-temperature visualization instruments were used and Differential thermal analysis (DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermodynamic analyses were performed to verify the relevant mechanism. The reaction between SiC and heat-resistant steel can be divided into two stages: solid–solid and solid–liquid reactions. The solid–solid interfacial reaction produces graphite, which hinders the interfacial reaction. The interfacial reaction simultaneously generates silicides (NiSi, Ni2Si, and Ni3Si) with low melting points and transforms the reaction interface into a solid–liquid interface. The formation of the liquid phase promotes the dissolution and diffusion of carbon, leading to the accelerated corrosion of SiC and low-temperature melting of steel. Supersaturated carbon precipitates in the melt in the form of nanowires or nanotubes are catalyzed by Fe/Ni. Herein, a general model describing the direct interfacial reaction mechanism of SiC and heat-resistant steel is proposed to explain the reaction process under vacuum.

Interaction between SOFCs interconnect Cr-free multicomponent spinel coating materials and chromia

Excellent Cr diffusion resistance and interface stability is essential for coatings applied on the surface of ferrite stainless steel interconnect for SOFCs. Four kinds of materials, the equimolar (MnFeCoNiCu)3O4 (Eq), non-equimolar (Mn0·272Fe0·272Co0·272Ni0·092Cu0.092)3O4 (Non-Eq), MnCo2O4 (MC) and the Quaternary (MnFeCoNi)3O4 (Quaternary), are combined with chromium oxide to form diffusion couples in order to study the interfacial reaction mechanism. The constitutes and morphologies of the samples are tested. Two different composition reaction layers are found in equimolar/Cr2O3 diffusion couple. A slight Cr inward diffusion is detected in Quaternary/Cr2O3 diffusion couple.

Kinetic and transport characteristics of LiNi0.8Co0.1Mn0.1O2 lithium-ion batteries

A balance must be found between energy density, cost and life for energy-typed lithium-ion batteries. Solving this problem requires a deep understanding of the electrode interface reaction mechanism. In this paper, electrochemical AC impedance spectroscopy (EIS) is used to study the impedance spectrum characteristics of lithium-ion batteries comprising LiNi0.8Co0.1Mn0.1O2 (NCM811) and graphite electrodes separately in a symmetrical battery system under different states of charge and temperature. The de Levie - Finite Length Pore (Ls) element is used to differentiate Li+ diffusion resistance Rion inside the porous electrode and charge transfer process resistance Rct in the Faraday reaction. The dependencies of Rion and Rct on temperature and state of charge (SOC) are obtained. Based on the Rion measurements, we calculate MacMullin number (Nm) and then characterize the difficulty of Li ion transportation of NCM811 and graphite electrodes in one cell. The results indicate directions for improving the power design of commercial energy-typed lithium-ion power batteries.

Recent advances in the application of scanning probe microscopy in interfacial electroanalytical chemistry

The electrochemical reaction mainly occurs at the electrode/electrolyte interface in the electrochemical system. For a fundamental insight into the interfacial reaction mechanism, in situ/operando analysis of the interfacial evolution at the microscale is essential. Scanning probe microscopy (SPM), noted for its high spatial resolution, real-time imaging, and multifunctional detection, is considered as one of the most important in situ analytical tools for the electrochemical interfaces from the atomic/molecular scale to the nanoscale. This review first introduces the brief principles of typical SPM, such as scanning tunneling microscopy, atomic force microscopy, and scanning electrochemical microscopy. The applications of in situ SPM in surface and interface analysis for electrochemical energy systems, including electrocatalysts and energy storage batteries, are then presented. In addition, in situ detection of the electric double layer and space charge layer is further discussed. Challenges and future developments in the field are proposed in the outlook.

High-voltage all-solid-state lithium batteries with Li3InCl6 electrolyte and LiNbO3 coated lithium-rich manganese oxide cathode

The all-solid-state lithium battery (ASSLB) with lithium-rich manganese oxide (LRMO) cathode material is one of the strongest competitors for the next generation energy-storage device with high energy density. However, due to the serious interfacial reaction between LRMO and halide solid-state electrolyte (SSE), its electrochemical performance cannot meet the practical demand. In this work, in-situ electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS) tests and high resolution transmission electron microscope (HR-TEM) are carried out to clarify the interfacial reaction mechanism between LRMO and Li3InCl6 (LIC). The active oxygen released from LRMO and phase transition of LRMO are confirmed to seriously deteriorate the LRMO/LIC interface. To solve the above problems, a uniform LiNbO3 coating is introduced to alleviate the interfacial side reaction and phase transition of LRMO. With moderate coating amount (1.5 wt%, ∼10 nm thick), the LNO@LRMO cathode shows an initial discharge capacity of 185 mA h g− 1 with 67% capacity retention after 100 cycles in halide-based ASSLB, which greatly exceeds that of bare LRMO cathode under voltage range of 2.3–4.8 V. This work provides a new perspective for improving the performance of LRMO in halide-based ASSLBs to achieve high energy density.

Performance and interfacial reaction mechanism of nano-IMC-mixed solder paste with variable melting point

Performance and interfacial reaction mechanism of nano-IMC-mixed solder paste with variable melting point

Theoretical Study on the Gas-Phase and Aqueous Interface Reaction Mechanism of Criegee Intermediates with 2-Methylglyceric Acid and the Nucleation of Products.

Criegee intermediates (CIs) are important in the sink of many atmospheric substances, including alcohols, organic acids, amines, etc. In this work, the density functional theory (DFT) method was used to calculate the energy barriers for the reactions of CH3CHOO with 2-methyl glyceric acid (MGA) and to evaluate the interaction of the three functional groups of MGA. The results show that the reactions involving the COOH group of MGA are negligibly affected, and that hydrogen bonding can affect the reactions involving α-OH and β-OH groups. The water molecule has a negative effect on the reactions of the COOH group. It decreases the energy barriers of reactions involving the α-OH and β-OH groups as a catalyst. The Born-Oppenheimer molecular dynamic (BOMD) was applied to simulate the reactions of CH3CHOO with MGA at the gas-liquid interface. Water molecule plays the role of proton transfer in the reaction. Gas-phase calculations and gas-liquid interface simulations demonstrate that the reaction of CH3CHOO with the COOH group is the main pathway in the atmosphere. The molecular dynamic (MD) simulations suggest that the reaction products can form clusters in the atmosphere to participate in the formation of particles.

The catalytic oxidation process of atrazine by ozone microbubbles: Bubble formation, ozone mass transfer and hydroxyl radical generation

Ozone microbubbles have received increasing attention since they can produce hydroxyl radical (•OH) to decompose ozone-resistant pollutants. Besides, compared with conventional bubbles, microbubbles have a larger specific surface area and higher mass transfer efficiency. However, the research on the micro-interface reaction mechanism of ozone microbubbles is still relatively scarce. Herein, we systematically studied the stability of microbubbles, ozone mass transfer and atrazine (ATZ) degradation through multifactor analysis. The results revealed that bubble size was dominant in the stability of microbubbles, and gas flow rate played a major role in ozone mass transfer and degradation effects. Besides, the bubble stability accounted for the different effects of pH on ozone mass transfer in two aeration systems. Finally, kinetic models were built and employed to simulate the kinetics of ATZ degradation by •OH. The results revealed that conventional bubbles could produce •OH faster compared with microbubbles under alkaline conditions. These findings shed light on the interfacial reaction mechanisms of ozone microbubbles.

Ion Transport and Electrochemical Reaction in LiNi0.5Co0.2Mn0.3O2-Based High Energy/Power Lithium-Ion Batteries

The high energy/power lithium-ion battery using LiNi0.5Co0.2Mn0.3O2 (NCM523 HEP LIB) has an excellent trade-off between specific capacity, cost, and stable thermal characteristics. However, it still brings a massive challenge for power improvement under low temperatures. Deeply understanding the electrode interface reaction mechanism is crucial to solving this problem. This work studies the impedance spectrum characteristics of commercial symmetric batteries under different states of charge (SOCs) and temperatures. The changing tendencies of the Li+ diffusion resistance Rion and charge transfer resistance Rct with temperature and SOC are explored. Moreover, one quantitative parameter, § ≡ Rct/Rion, is introduced to identify the boundary conditions of the rate control step inside the porous electrode. This work points out the direction to design and improve performance for commercial HEP LIB with common temperature and charging range of users.

Temperature dependence of interfacial reactions of sodium aluminosilicate glasses from reactive molecular dynamics simulations

Understanding the interfacial reactions of sodium aluminosilicate (NAS) glass surfaces in aqueous environments is of great scientific and technological importance. This work investigates the impact of temperature on the kinetics and mechanisms of NAS glass-water interfacial reactionsby using molecular dynamics simulations with reactive potentials. The results show that the propagation depth of water molecules increases significantly with increasing temperature from 298 Kto 363 K. Higher temperatures also accelerate the formation of silanol groups. Importantly, it was found that the hydrolysis of Al-O-Al and Si-O-Al linkages are more facile than Si-O-Si linkages for all the tested temperatures, suggesting that the Si-O-Si linkages are the most stable in the network glass structures. Higher concentration of Al2O3and higher Al/Na ratio lead to a decrease in dissolved Na+ion concentrations and a lower solution’s pH values, suggesting higher chemical durability of the glasses with the addition of alumina. The temperature was also found to affect the Na+ion dissolution kinetics. At 298 K, the dissolved Na+concentration saturates atAl/Na ratio close 1, but at 363 K, it decreases with increasing Al/Na ratio. These results provide atomistic insights into interfacial reaction mechanisms and temperature dependent reaction kineticsof NAS glasses.

Noncovalent interactions on the electrocatalytic oxidation of ethanol on a Pt/C electrocatalyst

AbstractDue to their environmentally friendly nature and high energy density, direct ethanol fuel cells have attracted extensive research attention in recent decades. However, the actual Faraday efficiency of the ethanol oxidation reaction (EOR) is much lower than its theoretical value and the reaction kinetics of the EOR is sluggish due to insufficient active sites on the electrocatalyst surface. Pt/C is recognized as one of the most promising electrocatalysts for the EOR. Thus, the microscopic interfacial reaction mechanisms of the EOR on Pt/C were systematically studied in this work. In metal hydroxide solutions, hydrated alkali cations were found to bind with OHad through noncovalent interactions to form clusters and occupy the active sites on the Pt/C electrocatalyst surface, thus resulting in low Faraday efficiency and sluggish kinetics of the EOR. To reduce the negative effect of the noncovalent interactions on the EOR, a shield was made on the electrocatalyst surface using 4‐trifluoromethylphenyl, resulting in twice the EOR catalytic reactivity of Pt/C.

Rapid membrane surface functionalization with Ag nanoparticles via coupling electrospray and polymeric solvent bonding for enhanced antifouling and catalytic performance: Deposition and interfacial reaction mechanisms

Electrospray is an effective, fast, and potentially scalable approach for membrane surface functionalization using various engineered nanomaterials (ENMs). However, the lack of fundamental understandings of the deposition process hinders the controlled deposition, efficient utilization, and long-term stabilization of the ENMs, and thus the practical applications of the nanocomposite membranes. To bridge this critical knowledge gap, advanced online characterization techniques (laser diffraction size measurement and laser doppler velocimetry) coupled with mathematical aerosol modeling are utilized to understand the three key process parameters: droplet size, deposition velocity, and evaporation rate. After deposition, polymeric solvent bonding (i.e., interdiffusion and subsequent entanglement of polymers) was found to substantially stabilize the deposited Ag NPs. We further provide a comprehensive description of such interfacial reaction mechanisms. Our results show a consistency between theoretical predication and measurement of the droplet size or deposition velocity, whereas realistic droplet evaporation rate is lower than the theoretical value due to the addition of the polymer. Successful stabilization of Ag NPs via interfacial polymeric bonding occurs under the conditions of large material contact area, high material compatibility, proper temperature (e.g., 22 °C), and polymer-to-solvent ratio (e.g., 3–5%). Our coupled approach achieves superior Ag NP coverage with high stability within minutes. Despite some reduction in water permeance, the resultant membrane shows markedly improved catalytic and antimicrobial (antibiofouling) performance (>90% enhancement) and maintained rejection. Taken together, our findings provide fundamental insights into the coupled process of electrospray deposition and polymeric solvent bonding to enable additive manufacturing of novel nanocomposite membranes with diverse structures and multiple functions.

Theoretical Study on the Gas Phase and Gas–Liquid Interface Reaction Mechanism of Criegee Intermediates with Glycolic Acid Sulfate

Criegee intermediates (CIs) are important zwitterionic oxidants in the atmosphere, which affect the budget of OH radicals, amines, alcohols, organic/inorganic acids, etc. In this study, quantum chemical calculation and Born-Oppenheimer molecular dynamic (BOMD) simulation were performed to show the reaction mechanisms of C2 CIs with glycolic acid sulfate (GAS) at the gas-phase and gas-liquid interface, respectively. The results indicate that CIs can react with COOH and OSO3H groups of GAS and generate hydroperoxide products. Intramolecular proton transfer reactions occurred in the simulations. Moreover, GAS acts as a proton donor and participates in the hydration of CIs, during which the intramolecular proton transfer also occurs. As GAS widely exists in atmospheric particulate matter, the reaction with GAS is one of the sink pathways of CIs in areas polluted by particulate matter.

B-doped NiFe2Ox based on the activation of peroxymonosulfate for degrading 2,4-dichlorophenoxyacetic acid in water

Catalysts used to degrade pollutants are easily limited by surface reaction sites. Herein, we modified the catalyst by doping boron (B) to overcome the above shortcomings. B-doped NiFe2Ox catalysts with oxygen vacancies (OVs) were synthesized by the sol–gel method to activate peroxymonosulfate (PMS) for 2,4-dichlorophenoxyacetic acid (2,4-D) degradation. 2,4-D is a widely used herbicide in agricultural production. However, it was difficult to be degraded and dangerous to human health. The B-doped NiFe2Ox (especially 10B-NiFe2Ox) exhibited a high catalytic capacity for 2,4-D, aceclofenac (ACF), bisphenol S (BPS) and amidotrizoic acid (DTZ). And the removal rate of 2,4-D in 10B-NiFe2Ox/PMS system was increased by 26.4 percentage points compared with NiFe2O4/PMS system. It was verified that B-O-Fe and B-O-Ni were formed. And OVs were formed on the surface of the catalyst after B doping. SO4− was confirmed as the major reactive oxygen species (ROS) by quenching experiments. Metal sites and OVs were conducive to the generation of SO4−. According to the in situ analysis of the interfacial reaction mechanism, the –OH structure of HSO5− and H2O could be adsorbed on the OVs sites and combined with the adjacent Lewis acid sites. The cycle of Fe2+/Fe3+ and Ni2+/Ni3+ promoted the interfacial electron transfer of the combined HSO5−, and thus generating SO4−. The degradation pathways of 2,4-D were proposed through its intermediates and density functional theory (DFT) calculation by the Fukui function. The degradation mechanism included decarboxylation, dechlorination, dehydroxylation, hydroxylation, H-abstraction, bond cleavage and ring opening. This study verified the possibility of highly efficient pollutant degradation by activating PMS with B-doped modified catalyst.