Solid Interfacial Reaction Research Articles

Nano-roughness effect on the interfacial thermal oxidation and surface catalytical recombination characteristics for silicon carbide based materials under non-equilibrium flow

With the rapid development of high-speed aircraft, the demanding for light, strong, reliable and high temperature resistive thermal protection material (TPM) is becoming urgent. High temperature material interface, such as silicon carbide (SiC) ceramic matrix composite, has received strong interest recently due to its high mechanical and thermochemical stability. For reactive interface development with nano-roughness under extremely hyperthermal non-equilibrium flow conditions for TPM applications, however, has not been reported yet. This work performs a systematic reactive molecular dynamics (RMD) study of the SiC surface morphology effect withstanding hyperthermal atomic oxygen (AO) impact via a gas–solid interface reaction model. The results show that a self-healing trend of the defect-rich silicon carbide surface with original nano-roughness is revealed towards a flatter interface accompanying with the oxidation process. The surface catalytic recombination coefficient is more sensitivity to the surface defects when wall temperature Tw > 500 K. Nano-roughness structure can also vary the main thermochemical reaction path at the thermochemical reactive interface: For the nano-groove surface model, the thermal oxidation reaction becomes dominant, while more pronounced surface catalytic recombination characteristics are revealed for the flat surface model. The mechanisms of roughness effect, surface temperature and gas impacting angle on the surface catalytic recombination, surface oxidation, and interface evolution are revealed, which advance our microscopic understanding of SiC interfacial performance with nano-roughness under non-equilibrium flow conditions.

In-situ texturing hollow carbon host anchored with Fe single atoms accelerating solid-phase redox for Li-Se batteries

Se-based cathodes have caught tremendous attention owing to their comparable volumetric capacity and better electronic conductivity to S cathodes. However, its low utilization ratio and sluggish redox kinetics due to the high reaction barrier of solid-phase transformation from Se to Li2Se limit its practical application. Herein, an in-situ texturing hollow carbon host by gas–solid interface reaction anchored with Fe single-atomic catalyst is designed and prepared for advanced Li-Se batteries. This Se host presents high pore volume of 1.49 cm3 g−1, Fe single atom content of 1.53 wt%, and its specific structure protects single-atomic catalyst from the destructive reaction environment, thus balancing catalytic activity and durability. After Se loading by reduction of H2SeO3, this homogenous Se-based cathode delivers a superior rate capacity of 431.3 mA h g−1 at 4C, and great discharge capacity of 301.8 mA h g−1 after 1000 cycles at 10C, with high Li-ion diffusion coefficient and capacitance-contributed ratio. The distribution of relaxation times analysis verifies solid-phase transformation mechanism of this cathode and density functional theory calculations confirm the adsorption and bidirectionally catalysis effect of Fe single-atomic catalyst. This work provides a new strategy to prepare high-efficient Se cathode associated with non-noble metal single atoms for high-performance Li-Se batteries.

Enhanced remediation of Cr(VI)-contaminated soil by modified zero-valent iron with oxalic acid on biochar

Hexavalent chromium (Cr(VI)) is carcinogenic and widely presented in soil. In this study, modified zero-valent iron (ZVI) with oxalic acid on biochar (OA-ZVI/BC) was prepared using wet ball milling method for the remediation of Cr(VI)-contaminated soil. Microscopic characterizations showed that ZVI were distributed on the biochar uniformly and confirmed the enhanced interface interaction between biochar and ZVI by wet ball milling. Electrochemical analysis indicated the strong electron transfer ability and enhanced corrosion behavior of OA-ZVI/BC. Moreover, inhibitory efficiencies of Cr(VI) removal with the addition of 1,10-phenanthroline suggested abundant Fe2+ generation in OA-ZVI/BC, which might facilitate the reduction of Cr(VI) to Cr(III). Theory calculation further demonstrated the ZVI modified by oxalic acid was more susceptible to solid–solid interfacial reactions with Cr(VI), and more electrons were transferred to Cr(VI). When applied to Cr(VI)-contaminated soil, OA-ZVI/BC could passivate 96.7 % total Cr(VI) and maintained for 90 days. The toxicity characteristic leaching procedure (TCLP) and simple based extraction test (SBET) were used to evaluate the leaching toxicity and bioaccessibility of Cr(VI), respectively. The TCLP-Cr(VI) decreased to 0.11 mg·L−1 after OA-ZVI/BC treatment, much lower than that of soils with ZVI/BC and OA-ZVI remediation (1.5 mg·L−1 and 4.1 mg·L−1). The bioaccessibility of Cr(VI) reduced by 93.5 % after 3-month remediation. Sequential extraction showed that Cr fractions in the soil after OA-ZVI/BC remediation was converted from acetic acid-extractable (HOAc-extractable) to more stable forms (e.g., residual and oxidizable forms). Benefiting from the synergies of oxalic acid, biochar and wet ball milling, OA-ZVI/BC exhibited an excellent performance on the remediation of Cr(VI)-contaminated soil, whose mechanisms involved adsorption, reduction (Fe0/Fe2+, Fe2+/Fe3+) and co-precipitation. This study herein develops a promising ZVI technology in the remediation of heavy metal-contaminated soil.

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.

Boosting the electrochemical performance of Li-rich Mn-based cathode materials via oxygen vacancy and spinel phase integration

Li-rich Mn-based oxide cathodes (LMOs) are regarded as one of the most prospective high energy density cathodes due to the reversible anion redox reaction, which gives them a very high capacity. However, LMOs materials usually have problems like low initial coulombic efficiency (ICE) and poor cycling performance during cycling, which are associated with irreversible surface O2 release and unfavourable electrode/electrolyte interface side reactions. Herein, an innovative and scalable NH4Cl-assisted gas–solid interfacial reaction treatment technique is employed to construct oxygen vacancies and spinel/layered heterostructures simultaneously on the surface of LMOs. The synergistic effect of the oxygen vacancy and the surface spinel phase can not only effectively enhance the redox properties of the oxygen anion and inhibit irreversible oxygen release, but also effectively mitigate the side reactions at the electrode/electrolyte interface, inhibit the formation of CEI films and stabilize the layered structure. The electrochemical performance of the treated NC-10 sample improved significantly, showing an increase in ICE from 77.4 % to 94.3 % and excellent rate capability and cycling stability, with a capacity retention of 77.9 % after 400 cycles at 1 C. This oxygen vacancy and spinel phase integration strategy offers an exciting prospect and avenue for improving the integrated electrochemical performance of LMOs.

Kinetics and Microstructure Transformations of Oxide Scale on Hot Rolled Steel Strip for Hot‐Dip Galvanizing during Reduction Annealing in 30% H2–N2 Atmosphere

The understanding of oxide scale reduction mechanisms after microstructure transformation under different preheating conditions is incomplete. Herein, the reduction kinetics and microstructure transformations of hot rolled steel strip oxide scale during reduction (30% H2–N2) annealing are studied in detail using thermogravimetric and microstructure analyses, and mathematical modeling based on the gas–solid reaction. The results show that the rate‐determining steps of the reduction reaction are nucleation and growth of new phase between 500 and 600 °C, and gas–solid interface reactions between 700 and 800 °C. Microstructure transformation of the oxide scale occurs during the preheating process: at 500 °C, the eutectoid iron preferentially dissolves, and short‐range diffusion of Fe ions into adjacent Fe3O4 increases their content in the metal oxide; at 600 °C, nucleation and growth of Fe1 − yO occur, and some Fe3O4 precipitates and white α‐Fe are found in the Fe1 − yO layer, whereas the majority of the Fe3O4/iron eutectoid structure is retained; between 700 and 800 °C, the oxide scale forms outer and inner layers of Fe3O4 and Fe1 − yO, respectively. After preheating and reduction, the reduced products are porous iron over 500–600 °C, while porous and dense iron occur at 700 °C; dense iron forms as whiskers or granules between 700 and 800 °C. The surface quality of hot rolled steel strip after reduction annealing is subsequently improved as surface cracks are infilled by the newly formed dense iron.

Addressing voltage hysteresis in Li-rich cathode materials via gas-solid interface modification.

Li-rich layered materials have attracted much attention for their large capacity (>250 mA h g-1) stemming from anion redox at high voltage. However, inherent problems, such as capacity decay and voltage decay/hysteresis during cycling, hinder their commercial progress. In this work, an oxygen vacancy-accompanied spinel interface layer is constructed by gas-solid reaction via NiCO3 treatment at 650 °C, which reduces the asymmetry of anion redox and improves structural stability. Therefore, a 1 mol% NiCO3-modified sample powerfully reduces the voltage hysteresis (∼0.23 V) in the first cycle, simultaneously exhibiting an excellent discharge capacity of 275 mA h g-1 at 0.1 C with a capacity retention of 90% for 200 cycles at 1 C.

Efficient Pb(II) adsorption in aqueous solution by hierarchical 3D/2D TiO2/CNNS nanocomposite

A multifunctional nanomaterial for contaminants’ removal and solar fuel production is designed, for solving environmental and energy problems. In this research, hierarchical three-dimensional (3D)TiO2 doped with porous graphite-like two-dimensional (2D) carbon nitride (g-C3N4) nanosheets (TiO2/CNNS) composite was fabricated by solid interfacial reaction through a facile acid hydrothermal route. Interestingly, the produced catalyst showed extraordinarily selective adsorption towards Pb (II) metal ions through strong electrostatic attraction mainly due to the enlarged surface areas and pore volume, besides increased adsorption/active sites. The obtained batch mode adsorption measurements reveal a high removal efficiency of give 378 mg.g−1 in a very short period of time of 7 min. This study highlights the importance of designing 3D/2D multifunctional g-C3N4-based photocatalysts for environmental heavy metals decontamination.

Investigation of the Sn-0.7 wt.% Cu Solder Reacting with C194, Alloy 25, and C1990 HP Substrates

Cu-based alloys are one of the most promising substrates to enhance the performance of lead-frame materials. In the present study, the interfacial reactions in the Sn-0.7 wt.% Cu (SC) lead-free solder reacting with Cu-3.3 wt.% Fe (C194), Cu-2.0 wt.% Be (Alloy 25), and Cu-3.3 wt.% Ti (C1990 HP) were investigated. The material underwent a liquid–solid interface reaction, and the reaction time was 0.5 to a few hours at the reaction temperatures of 240 °C, 255 °C, and 270 °C. The morphology, composition, growth rate, and growth mechanism of the intermetallic compounds (IMCs) formed at the interface were investigated in this study. The results showed that the reaction couples of SC/C194, SC/Alloy 25, and SC/C1990 HP formed IMCs, which were the [(Cu, Fe)6Sn5 and (Cu, Fe)3Sn], [(Cu, Be)3Sn and (Cu, Be)6Sn5], and [Cu6Sn5] phases, respectively. Finally, the IMC growth mechanism for the SC/C194, SC/Alloy 25, and SC/C1990 HP couples displayed reaction control, grain boundary diffusion control, and diffusion control, respectively.

Microstructure-Controlled Li-Rich Mn-Based Cathodes by a Gas–Solid Interface Reaction for Tackling the Continuous Activation of Li2MnO3

Li-rich Mn-based cathodes have attracted much attention due to their high capacity stemming from anion redox above 4.5 V. However, the continuous activation of Li2MnO3 in Li-rich Mn-based materials, which correlates with O2 release and TM migration, is usually unfavorable to structural stability. Herein, based on a gas-solid interface reaction, we tackle this continuous activation phenomenon by restricting the capacity release of Li2MnO3 via NH4HCO3 treatment in the Li1.2Ni0.36Mn0.44O2 cathode. After modification, oxygen vacancies associated with the spinel phase are introduced on the surface. The 4 mol % NH4HCO3-modified material's capacity starts at 182 mAh g-1 at 1 C instead of increasing from 173 to 186 mAh g-1 for 25 cycles in the pristine material. Meanwhile, it also exhibits an excellent capacity retention of 93.24% after 200 cycles (at 1 C), with a small voltage decay rate of 1.19 mV cycle-1.

Unusual redox activity of the central heteroatom manganese in Anderson anion: Modulating its oxidation state in a gas solid reaction

The orange crystalline [N(C4H9)4]3[MnIIIMo6O18{(OCH2)3CNH2}2] (1) with central Mn(III), on exposure to vapors of conc. HCl is converted to green colour solid of tentative formula, [N(C4H9)4]2[MnIIMo6O18{(OCH2)3CNH3}2] ∙ [N(C4H9)4]Cl (1red). Compound 1, on exposure to conc. HNO3 vapours is converted to brown solid, which has tentatively been formulated as [MnIVMo6O18{(OCH2)3CNH3}2] ∙ 3[N(C4H9)4]NO3 (1ox). The color changes are associated with oxidation of central Mn(III) center of compound 1 into Mn(IV) in compound 1ox and reduction of central Mn(III) center of compound 1 into Mn(II) in compound 1red. Both solid state reduction and oxidation of Mn(III) center are accompanied by the protonation of amino group of tris(hydroxymethyl) aminomethane during the gas–solid interface reactions. The conversion of compound 1 into compounds 1red and 1ox in gas solid redox reactions has been characterized by various spectroscopic techniques, e.g., FT-IR, PXRD, EPR, DRS, 1H NMR, 13C NMR and XPS. Also, electrochemical analyses were carried out for all the compounds.

Achieving F-doped porous hollow carbon nanospheres with ultrahigh pore volume via a gas–solid interface reaction

Gas–solid interface engineered ultrahigh-pore-volume F-doped hierarchical porous hollow carbon nanospheres for high-sulfur-content Li–S batteries.

Promotional role of Mo on Ce0.3FeOx catalyst towards enhanced NH3-SCR catalytic performance and SO2 resistance

The SO2 resistance of low temperature NH3-SCR in non-electric power industries has always been the bottleneck of this technology. Herein, a series of Mo-modified Ce0.3FeOx catalysts (MoaCe0.3FeOx) were synthesized by an easy to scale-up, environment-friendly two-step solid interface reaction and applied to the treatment of flue gas from the glass industry. Incorporation of Mo into Ce0.3FeOx catalyst could not only remarkably expand the operation temperature window in both low and high temperature regions, but also maintain high catalytic activity (>85% NOx conversion) under 65 h long stability test conditions even with the coexistence of H2O and SO2. The two-step interface reaction over MoaCe0.3FeOx provided an increased specific surface area and more amorphous structure, forming highly dispersed MoO3 species on the surface of the catalyst which serves as a sacrificial site to react with SO2. The process of redox reaction has been greatly improved due to the facilitated electron transfer between Fe2+ and Ce4+ as well as more oxygen vacancies and active oxygen. The enhanced presence of NH4+ could react with gaseous NO species via Eley–Rideal (E–R) mechanism due to the lack of nitrate species (greatly inhibited) while the NH4NO3 was not generated during the reaction which is responsible for excellent low temperature SCR performance as well as high N2 selectivity. Furthermore, less sulfate species and no bulk sulfate were formed, which indicated that the doping of Mo could effectively reduce the basic sites and delay the irreversible deactivation as well as reduce catalyst sulphation. The above features provide a strategy for design and development of non-vanadium-based catalysts with low temperature SO2 resistance in non-electric power industries with high NOx emission concentrations.

Anisotropically Electrochemical–Mechanical Evolution in Solid‐State Batteries and Interfacial Tailored Strategy

AbstractAll‐solid‐state batteries have attracted attention owing to the potential high energy density and safety; however, little success has been made on practical applications of solid‐state batteries, which is largely attributed to the solid–solid interface issues. A fundamental elucidation of electrode–electrolyte interface behaviors is of crucial significance but has proven difficult. The interfacial resistance and capacity fading issues in a solid‐state battery were probed, revealing a heterogeneous phase transition evolution at solid–solid interfaces. The strain‐induced interfacial change and the contact loss, as well as a dense metallic surface phase, deteriorate the electrochemical reaction in solid‐state batteries. Furthermore, the in situ growth of electrolytes on secondary particles is proposed to fabricate robust solid–solid interface. Our study enlightens new insights into the mechanism behind solid–solid interfacial reaction for optimizing advanced solid‐state batteries.

The interfacial Cu–Sn intermetallic compounds (IMCs) growth behavior of Cu/Sn/Cu sandwich structure via induction heating method

Forming full IMC solder joint technology has become one of the leading candidates to replace conventional high temperature Pb-based solder for wide bandgap (WBG) power modules (SiC and GaN) due to its excellent thermo-stability and high electrical/thermal conductivity. Few studies were investigated the formation and growth mechanism of interfacial Cu–Sn IMCs layer of Cu/Sn(10 μm)/Cu system during induction heating method. The results showed that the growth behavior of Cu–Sn IMCs of the Cu/Sn interface by induction heating method was different from Cu–Sn IMCs growth behavior of the Cu/Sn interface by conventional soldering method. The Cu6Sn5 thickness increased by Cu/Sn solid–liquid interfacial reaction before the bonding time of 45 s and then decreased by Cu6Sn5/Cu solid–solid interfacial reaction within the bonding time of 60 s. The Cu3Sn thickness increased by solid Cu/liquid Sn interfacial reaction and solid Cu6Sn5/solid Cu interfacial reaction within the bonding time of 60 s. A formation mechanism model of Cu–Sn compounds was also presented. The mathematic model of Cu layer consumption at different temperature was also illustrated, which indicated that higher temperature is in favor of the consumption of Cu layer. By knowing the relationship between the thickness of Cu layer on SiC power device at different temperature could be designed when evaluating the reliability of device by induction heating process.

Taming Active Material-Solid Electrolyte Interfaces with Organic Cathode for All-Solid-State Batteries

Summary Attaining stable active material-solid electrolyte interfaces is a great challenge in sulfide-based all-solid-state sodium batteries (ASSSBs). A resistive layer forms at the interface upon charging above the anodic stability potential of sulfide electrolytes. In addition, contact failure at the interface during cycling is long known, but a fundamental solution is not yet available. Herein, we use an organic cathode material, pyrene-4,5,9,10-tetraone (PTO), to enable high-performance ASSSBs. We report, for the first time, a reversible active material-electrolyte interfacial resistance evolution during cycling. We further show for the first time that a low-modulus cathode material such as PTO maintains intimate interfacial contact with solid electrolytes during cycling, thus improving cycle life. The PTO-based cells exhibit a high specific energy (587 Wh kg−1) and a record cycling stability (500 cycles) among ASSSBs. This work reveals an effective cathode material design strategy toward compatibility with solid electrolytes and thus high-performance ASSSBs.

Experimental and Theoretical Investigation of Mesoporous MnO2 Nanosheets with Oxygen Vacancies for High-Efficiency Catalytic DeNOx

A solvent-free synthetic method was employed for the construction of mesoporous α-MnO2 nanosheets. Benefiting from a solid interface reaction, the obtained MnO2 nanosheets with large oxygen vacancies exhibit a high surface area of up to 339 m2/g and a mesopore size of 4 nm. The MnO2 nanosheets as a catalyst were applied in NH3-assisted selective catalytic reduction (NH3-SCR) of DeNOx at a relatively low temperature range. The conversion efficiency could reach 100% under a gas hourly space velocity (GHSV) of 700000 h–1 at 100 °C. To gain insight into the mechanism about NH3-SCR of nitric oxide on the MnO2 nanosheets, temperature-programmed desorption of NH3, a density functional theory study, and in situ diffuse reflectance infrared Fourier transform spectra were carried out, revealing the cooperative effect of catalytic sites on the reduction of nitric oxide. This work provides a strategy for the facile preparation of porous catalysts in low-temperature DeNOx.

Probing Solid–Solid Interfacial Reactions in All-Solid-State Sodium-Ion Batteries with First-Principles Calculations

We present an exposition of first-principles approaches to elucidating interfacial reactions in all-solid-state sodium-ion batteries. We will demonstrate how thermodynamic approximations based on assumptions of fast alkali diffusion and multispecies equilibrium can be used to effectively screen combinations of Na-ion electrodes, solid electrolytes, and buffer oxides for electrochemical and chemical compatibility. We find that exchange reactions, especially between simple oxides and thiophosphate groups to form PO43–, are the main cause of large driving forces for cathode/solid electrolyte interfacial reactions. A high reactivity with large volume changes is also predicted at the Na anode/solid electrolyte interface, while the Na2Ti3O7 anode is predicted to be much more stable against a broad range of solid electrolytes. We identify several promising binary oxides, Sc2O3, SiO2, TiO2, ZrO2, and HfO2, that are similarly or more chemically compatible with most electrodes and solid electrolytes than the common...

Development of Solid Catalyst–Solid Substrate Reactions for Efficient Utilization of Biomass

Abstract The efficient catalytic conversion of lignocellulose is a formidable issue, but it is worth studying in terms of the high potential as renewable chemical feedstock. In this account, we describe our approach to convert solid cellulose with solid catalysts. We found that carbons bearing weak acid sites were active for the hydrolysis of cellulose. The catalyst produced glucose in up to 88% yield after the formation of good solid–solid contact, due to selective enhancement of the solid–solid interfacial reaction. We also developed a cyclic system to efficiently convert real lignocellulosic biomass. Mechanistic study has revealed that polycyclic carbon aromatics attract cellulose by CH–π interactions mainly consisting of dispersion forces and hydrophobic interactions. The adsorbed cellulose molecules diffuse on the surface, rapidly penetrate even micropores, and undergo hydrolysis by weak acid sites such as carboxylic acids. Phenolic or carboxylic groups adjacent to the weak acid increase the frequency factor by forming hydrogen bonds. The combined functions of carbon derived from both polar and non-polar groups achieve the hydrolysis of cellulose. Finally, we comment on future perspective to apply these findings.

In situ study on liquid structure of Sn during Sn/Cu liquid–solid interfacial reaction by fluorescence XAFS

Fluorescence X-ray Absorption Fine Structure (XAFS) was used to in situ study the local structure around Cu atoms in liquid Sn solder during Sn/Cu liquid–solid interfacial reaction. The extended edge data were analyzed by cumulant expansion method. The results showed that both the atomic distance and the coordination number in the first shell decreased with the increase of temperature. It is an intrinsic trend that high-coordinated polyhedrons could transform into low-coordinated ones with relatively high stability in the liquid Sn solder with increasing temperature, and the high-coordinated polyhedrons always had larger atomic distance. The atomic distance in the first shell decreased with decreasing coordination number. Based on the fitting results, the proportion of Cu–Sn atomic coordination increased with rising soldering temperature from 250 to 310 °C. That is, Cu atoms preferred to form Cu–Sn interaction with Sn atoms, which promoted the nucleation and growth of Cu6Sn5 intermetallic compound at the Sn/Cu interface during soldering process.