Solid Interfacial Reaction Research Articles

Morphology-dependent structures and catalytic performances of Au nanostructures on Cu2O nanocrystals synthesized by galvanic replacement reaction

Au nanostructures were prepared on uniform Cu2O octahedra and rhombic dodecahedra via the galvanic replacement reaction between HAuCl4 and Cu2O. The compositions and structures were studied by Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), High-Resolution Transmission Electron Microscope (HRTEM), X-Ray Diffraction (XRD), X-Ray Absorption Spectroscopy (XAS), X-ray Photoelectron Spectroscopy (XPS) and in-situ DRIFTS spectroscopy of CO adsorption. Different from the formation of Au–Cu alloys on Cu2O cubes by the galvanic replacement reaction (ChemNanoMat 2 (2016) 861-865), metallic Au particles and positively-charged Au clusters form on Cu2O octahedra and rhombic dodecahedra at very small Au loadings and only metallic Au particles form at large Au loadings. Metallic Au particles on Cu2O octahedra and rhombic dodecahedra are more active in catalyzing the liquid phase aerobic oxidation reaction of benzyl alcohol than positively-charged Au clusters. These results demonstrate an obvious morphology effect of Cu2O nanocrystals on the liquid–solid interfacial reactions and prove oxide morphology as an effective strategy to tune the surface reactivity and catalytic performance.

Gas-solid interfacial modification of oxygen activity in layered oxide cathodes for lithium-ion batteries.

Lattice oxygen can play an intriguing role in electrochemical processes, not only maintaining structural stability, but also influencing electron and ion transport properties in high-capacity oxide cathode materials for Li-ion batteries. Here, we report the design of a gas–solid interface reaction to achieve delicate control of oxygen activity through uniformly creating oxygen vacancies without affecting structural integrity of Li-rich layered oxides. Theoretical calculations and experimental characterizations demonstrate that oxygen vacancies provide a favourable ionic diffusion environment in the bulk and significantly suppress gas release from the surface. The target material is achievable in delivering a discharge capacity as high as 301 mAh g−1 with initial Coulombic efficiency of 93.2%. After 100 cycles, a reversible capacity of 300 mAh g−1 still remains without any obvious decay in voltage. This study sheds light on the comprehensive design and control of oxygen activity in transition-metal-oxide systems for next-generation Li-ion batteries.

From Solid-State Dewetting of Ultrathin, Compressively Strained Silicon–Germanium-on-Insulator Films to Mastering the Stoichiometry of Si1–xGex Nanocrystals

The mastering of material composition at the nanoscale is of prime importance for many applications. In this context, we developed a simply implementable and fast germanium enrichment method allowing the control of the germanium fraction within silicon–germanium nanocrystals. In our process, the tuning of the stoichiometry is achieved in the background of thermally induced solid-state dewetting, followed by a solid–solid interfacial reaction step between nanocrystals issued from dewetting and the silicon dioxide substrate. At first, we show by scanning transmission electron microscopy and scanning Auger microscopy that homogeneous silicon–germanium nanocrystals are successfully formed by means of solid-state dewetting of silicon–germanium-on-insulator ultrathin films. Then, we demonstrate that an interfacial reaction between the silicon–germanium of the nanocrystals and the silicon dioxide of the substrate can be thermally induced under ultrahigh vacuum conditions. The reaction, entailing almost exclusive...

Reversible solid to solid transformation in a crystalline state gas–solid reaction under ambient conditions: Fe–N(pyridine) bond formation at the expense of Fe–OH2bond breaking and vice versa

The non-porous crystalline state of a trinuclear iron cluster containing compound [Fe3(μ3-O)(μ2-CH3COO)6(C5H5NO)2(H2O)]ClO4·3H2O (1) demonstrates a series of crystalline state reactions that can be stimulated by an external substrate, such as methanol or pyridine. This simple trinuclear {μ3-O} cluster [Fe3(μ3-O)(μ2-CH3COO)6(C5H5NO)2(H2O)]1+ exhibits reversible gas–solid reactions driven by the ligand exchange at one of its metal centres that involve Fe–OH2 bond breaking and Fe–N(pyridine) bond formation in the solid state in a reversible crystal to crystal transformation. The gas–solid interface reactions have been confirmed by IR spectroscopy and powder X-ray diffraction studies. A classical trinuclear iron {μ3-O} cluster with a slight modification in its basic molecular structure opens up new possibilities that can find applications in the development of multi-functional materials. The reversible solid to solid transformations in the present article have been established by various spectroscopic arguments.

Compositions, structures, and catalytic activities of CeO₂@Cu₂O nanocomposites prepared by the template-assisted method.

CeO2@Cu2O nanocomposites were prepared from Cu2O cubes and octahedra by the template-assisted method involving the liquid (Ce(IV))-solid (Cu2O) interfacial reaction. Their compositions, structures, and catalytic activities in CO oxidation were studied in detail. Under the same reaction conditions, CeO2@Cu2O nanocomposites prepared from cubic and octahedral Cu2O templates exhibit different compositions and structures. With an increasing amount of Ce(IV) reactant, a smooth CeO2-CuOx shell develops on the surface of Cu2O cubes and eventually void cubic core/multishell Cu2O/CeO2-CuOx nanocomposites form; however, a rough CeO2-CuOx shell develops on the surface of Cu2O octahedra, and eventually hollow octahedral CeO2-CuOx nanocages form. The formation of different compositions and structures of CeO2@Cu2O nanocomposites was correlated with the different exposed crystal planes and surface reactivities of Cu2O cubes and octahedra. The catalytic activity of CeO2@Cu2O nanocomposites in CO oxidation depends on their compositions and structures. The most active CeO2@Cu2O nanocomposites become active at 70 °C and achieve a 100% CO conversion at 170 °C. These results broaden the versatility of Cu2O nanocrystals as the sacrificial template for the fabrication of novel nanocomposites with core/shell and hollow nanostructures and exemplify the morphology effect of Cu2O nanocrystals in liquid-solid interfacial reactions with respect to the composition, structure, and properties of nanocomposites prepared by the template-assisted method.

Liquid–solid interfacial reactions of Sn–Ag and Sn–Ag–In solders with Cu under bump metallization

Intermetallic compounds formed during the liquid–solid interfacial reaction of Sn–Ag and Sn–Ag–In solder bumps on Cu under bump metallization at temperatures ranging from 240 to 300 °C were investigated. Two types of intermetallic compounds layer, η Cu6Sn5 type and e Cu3Sn type, were formed between solder and Cu. It was found that indium addition was effective in suppressing the formation of large Ag3Sn plate in Sn–Ag solder. During interfacial reaction, Cu consumption rate was mainly influenced by superheat of solder, contact area between solder and Cu and morphology of intermetallic compounds. The growth of η intermetallic compounds was governed by a kinetic relation: ΔX = tn, where the exponent n values for Sn–Ag/Cu and Sn–Ag–In/Cu samples at 240 °C were 0.35 ± 0.01 and 0.34 ± 0.02, respectively. The n values increased with reaction temperature, and it was higher for Sn–Ag/Cu than that for Sn–Ag–In/Cu sample at the same temperature. After Cu was exhausted, e intermetallic compound was converted to η intermetallic compound. The mechanisms for such growth of interfacial intermetallic compounds during the liquid–solid reaction were investigated.

Highly sensitive electrochemical stripping detection of hepatitis B surface antigen based on copper-enhanced gold nanoparticle tags and magnetic nanoparticles

On the basis of copper-enhanced gold nanoparticle tags as an amplification approach, we introduced, in this paper, magnetic nanoparticles for further improving performance of electrochemical immunoassay by anodic stripping voltammetry (ASV) at a glassy-carbon electrode. Due to the use of antibody-immobilized magnetic nanoparticles, the immunoreaction between antibody and antigen takes place in a homogeneous bulk solution phase. Compared with traditional solid interface reaction, the proposed strategy can provide some advantages such as easy of separation, shorter analytical time, wider linear range, and lower detection limit. It was also successfully applied to HBsAg determination in a linear range of 0.1–1500 ng mL −1 with a detection limit of 87 pg mL −1. The proposed analytical strategy holds good selectivity, sensitivity and repeatability and also great promise for the extended application in the fields of clinical diagnosis, bio-affinity assay and environmental monitoring.

Interfacial reaction between Au and Sn films electroplated for LED bumps

Au-20 wt% Sn eutectic solder is used as bumps in flip chip package of power LED (Light Emitting Diode) due to its excellent properties. The Au/Sn dual-layer films were fabricated on Si wafer by pulse electroplating of Au and Sn sequentially, and the solid–solid interfacial reaction during aging and the eutectic reaction during reflow soldering were investigated in the present work. After storage at room temperature for 1 week, three phases of AuSn, AuSn2 and AuSn4 were sequentially formed at the Au/Sn (10 μm/10 μm) interface, and the thickness of this reaction region was about 5 μm. Firstly, AuSn4 was formed at the Au/Sn interface, and then AuSn and AuSn2 were formed at the Au/AuSn4 interface. After aging at 150 °C for 5 and 10 h, a similar layered structure of AuSn/AuSn2/AuSn4 was also observed. Due to the faster diffusion of Au to Sn layer, all the Sn elements were consumed after aging at 150 °C for 15 h and AuSn4 layer gradually transformed into AuSn and AuSn2 layers. For the specimen of Au/Sn (9 μm/6 μm) films on Si chip, a bamboo-shoot-like microstructure of Au5Sn/AuSn/AuSn2 was formed in the reaction region after reflowed at 280 °C for 10 s; while a typical two-phase (Au5Sn and AuSn) eutectic microstructure was formed after reflowed at 280 °C for 60 s.

Interfacial reaction and the dominant diffusing species in Mg–Ni system

Abstract The solid–solid interfacial reaction in the Mg–Ni binary diffusion couples was studied for the first time in bulk form. The reaction temperature was at 400, 430, 450, and 480 °C, with reaction time ranging from 10 to 75 h. The Mg–Ni phase diagram shows two stable compounds, Mg 2 Ni and MgNi 2 , at these temperatures, but only Mg 2 Ni was observed at the interface after the reaction. The growth of Mg 2 Ni followed the parabolic kinetics, and the apparent activation energy was determined to be 120 kJ/mol. The dominant diffusing species was identified by using thin W lines as markers. After the reaction, these W markers located near the Mg/Mg 2 Ni interface, suggesting that Mg was the dominant diffusing species in Mg 2 Ni. This is consistent with the general trend that in many metal/metal systems the dominant diffusing species are usually the majority elements in the compounds that formed first.

Hierarchical Three-Dimensional ZnO and Their Shape-Preserving Transformation into Hollow ZnAl2O4 Nanostructures

We present novel three-dimensional (3D) hierarchical ZnO and ZnAl2O4 nanostructures produced by multitransformation reactions using Zn as the starting material. In two representative instances selected for illustrating this strategy, various Zn precursors like Zn nanowires and polyhedral Zn microcrystals were first prepared by physical vapor deposition without any catalyst. Subsequently, we successfully synthesized branched ZnO nanowires and hollow ZnO polyhedrons with vertically aligned ZnO nanowires by oxidizing Zn nanowires and polyhedral Zn microcrystals, respectively, under optimal conditions. The growth of both ZnO nanobranches and vertically aligned nanowires was suggested as a self-supplying and self-catalytic process following the vapor transport solid condensation mechanism. Furthermore, the obtained ZnO nanostructures were homogeneously covered by a shell of amorphous Al2O3 using atomic layer deposition. Through the solid–solid interfacial reaction of ZnO and Al2O3, the 3D nanostructures were transformed to hierarchical ZnAl2O4 nanostructures conserving the shape of the corresponding ZnO nanostructures. Particularly, all the ZnAl2O4 nanobranches or vertically aligned 1D structures exhibited a tubular structure, which was induced by the nanoscale Kirkendall effect. This work demonstrates a simple and efficient pathway to design hierarchical ZnO and complex hollow zinc spinel nanostructures, which are expected to have potential applications in nanotechnology.

Synthesis of Body-Centered Cubic Carbon Nanocrystals

A kind of carbon nanocrystals with body-centered cubic (bcc) structure has been synthesized by using a pulsed-laser induced liquid–solid interface reaction (PLIIR). Scanning electron microscopy, Raman spectra, transmission electron microscopy with energy dispersive X-ray spectrometry, selected area electronic diffraction, and high-resolution analysis are employed to characterize the morphology, composition, and structure of the synthesized nanocrystals. The experimental analyses show that the synthesized nanocrystals are single crystals with a bcc structure, the so-called C8, which was theoretically predicted by Johnston and Hoffmann. Carbon with a bcc structure has potential applications in mechanical engineering and electronics, because it is superdense and superhard. The synthesis mechanisms of bcc carbon nanocrystals by PLIIR are studied.

Micro- and Nanocubes of Silicon with Zinc-Blende Structure

Micro- and nanocubes of single-crystalline silicon with the zinc-blende structure have been synthesized by pulsed-laser-induced liquid–solid interface reaction. Raman scattering, scanning electron microscopy, transmission electronic microscopy equipped with energy dispersive X-ray spectrometer, selected area electron diffraction, and electron energy-loss spectroscopy are employed to characterize the morphology and structure of the as-synthesized samples. The first-principles calculations are employed to theoretically analyze the data of experiments. The synthesis mechanisms of silicon cubes upon PLIIR are pursued in physical and chemical mechanisms.

Metallurgy and Kinetics of Liquid–Solid Interfacial Reaction during Lead-Free Soldering

The wetting of a molten solder on metallic surfaces is a rather complex phenomenon. In addition to physical spreading due to surface tension reduction, there are interfacial metallurgical and flux chemical reactions with the metallic substrate surface. Substrate dissolution and intermetallic formation take place rapidly during soldering. Since lead-free soldering requires substantially higher soldering temperatures (around 250 � C), the rates of intermetallic growth and substrate dissolution for lead-free solders are expected to be significantly greater than those for the current Sn–Pb eutectic solder. This study systematically investigates the metallurgy of the solid–liquid interface reactions and intermetallic growth kinetics for three lead-free solders: Sn–Ag eutectic (96.5%Sn–3.5%Ag), Sn–Cu eutectic (99.3%Sn–0.7%Cu) and Sn–Ag– Cu eutectic (Sn–3.8Ag–0.7Cu, SAC 387) with three metallic substrates: Cu, Ni, and Alloy 42 (42%Ni–52%Fe) over temperatures ranging from 225 to 280 � C for reaction time from 10 s to 16 h. Wetting behavior of these three alloys on PCBs with OSP, immersion Sn, and Ni/Au finishes, was also examined from 220 � C up to 260 � C. A thorough understanding of lead-free solder/substrate interfacial reactions should give guidance to the optimum lead-free soldering processes and to the optimum lead-free coating thicknesses for component and PCB terminal finishes, as well as for under-chip metallurgical coatings for flip-chip and BGA applications.

Explosion Phase Formation of Nanocrystalline Boron Nitrides Upon Pulsed-Laser-Induced Liquid/Solid Interfacial Reaction

Boron nitride (BN) nanocrystals with explosion (E) phase were prepared by a novel laser-assisted materials fabrication, i.e., pulsed-laser-induced liquid (acetone)/solid (hexagonal boron nitride bulk) interfacial reaction at normal temperature and pressure. Typical diameters of these synthesized quasi-spherical BN nanocrystals were in the range of 30 to 80 nm. Transmission electron microscopy, x-ray diffraction, and Fourier transformed infrared spectroscopy were used to identify the morphologies and structures of the synthesized nanocrystals. Additionally, we proposed the formation mechanism of cubic-BN and E-BN nanocrystals upon pulsed-laser-induced liquid/solid interfacial reaction, in which both liquid and solid were simultaneously involved.

Phase transition between cubic-BN and hexagonal BN upon pulsed laser induced liquid–solid interfacial reaction

The phase transformation between cubic boron nitride (c-BN) and hexagonal boron nitride (h-BN) from the c-BN nanocrystals synthesis by pulsed laser induced liquid–solid interfacial reaction (PLIIR) was studied by calculating the probability of phase transition of the h-BN structure over a potential barrier in boron nitride equilibrium phase diagram. Consequently, we found that the probability of phase transition from h-BN to c-BN goes up to 10 −5–10 −4 in the pressure–temperature region of 5–6 GPa and 2500–3500 K created by PLIIR. Furthermore, the probability distribution of the phase transition from h-BN to c-BN was obtained in the corresponding pressure–temperature region, and the dependence of phase transition probability on temperature was found to be in agreement with the Arrhenius rule.

Cubic-BN nanocrystals synthesis by pulsed laser induced liquid–solid interfacial reaction

Cubic boron nitride (c-BN) nanocrystals have been synthesized by pulsed laser induced liquid–solid interfacial reaction. It is shown that the diameters of the prepared quasi-spherical c-BN nanocrystals vary from 30 to 80 nm via transmission electron microscopy (TEM). The 2 θ values of the X-ray diffraction (XRD) peaks of the resultant c-BN nanocrystals are 43.16°, 74.16°, 90.08° and 136.1°, respectively, corresponding to the (1 1 1), (2 2 0), (3 1 1) and (3 3 1) crystalline planes of a c-BN phase. Fourier transform infrared (FTIR) spectroscopy has also been used to characterize the structure of boron nitride. The formation of c-BN nanocrystals upon pulsed laser ablation at the liquid–solid interface is discussed in detail.

Cubic and hexagonal structures of diamond nanocrystals formed upon pulsed laser induced liquid–solid interfacial reaction

Diamond nanocrystals with cubic and hexagonal structures have been prepared by pulsed laser induced liquid–solid (acetone1–graphite) interfacial reaction (PLIIR) at normal temperature and pressure. The structure and morphology of the resulted diamond nanocrystals were characterized by transmission electron microscopy (TEM). The Raman spectroscopy analysis of the obtained diamond nanocrystals showed that three diamond Raman lines, i.e., 1307, 1100, and 623 cm −1 were observed. Interestingly, the Raman line at 1100 cm −1 was identified to be original from nano-diamond. In addition, a new Raman line at 926 cm −1 due to diamond was observed in the Raman spectra (RS).

Fabrication of Powders and Thin Films of Various Nickel Sulfides by Soft Solution-Processing Routes

We have demonstrated a soft solution-processing route for selective synthesis of various phases of nickel sulfides, in which a novel liquid–solid interfacial reaction between a nickel substrate and sulfur is involved, and the reaction of the Ni2+ ion with sulfur in different solvents at low temperatures (≤ 200 °C). Nanostructured Ni3S2 thin films, NiS (millerite) nanowhiskers, and NiS2 single crystals with dodecahedron {101} unit polytype shape were directly synthesized in ethylenediamine. Similar reactions in other solvents were also investigated. In addition, a new molecular precursor Ni(en)xSy (where (en) is the ethylenediamine ligand) with the composition Ni(en)3S4 derived in ethylenediamine was found to be an excellent precursor for synthesis of nickel sulfide nanoparticles. The reaction mechanism, phase formation, and transformation process are proposed. Nickel sulfide materials with different phases and special shapes could find applications in catalysis, semiconductors, and magnetic devices.

Carbon nitride nanocrystals having cubic structure using pulsed laser induced liquid–solid interfacial reaction

Carbon nitride nanocrystals were prepared using a pulsed laser induced liquid–solid interfacial reaction and transmission electron microscopy, while high resolution electron microscopy characterized their morphology and structure. It is important that the cubic-C3N4 phase was observed. The formation mechanism of the carbon nitride nanocrystals is also discussed.

Phase transformation between diamond and graphite in preparation of diamonds by pulsed-laser induced liquid-solid interface reaction

The phase transformation between diamond and graphite in preparation of diamond by pulsed-laser-induced liquid - solid interface reaction (PLIIR) was studied by calculating the probability of phase transition of the carbon atoms over a potential barrier in the pressure-temperature (P - T) phase diagram of carbon. It is found that the probability of phase transition from graphite to diamond is as high as 10-3-10-4 in the C pressure - temperature region where the pressure and temperature are in the range of 10 GPa to 15 GPa and 4000 K to 5000 K, respectively, in the pressure - temperature phase diagram. The distribution of the probability of the phase transformation from graphite to diamond was obtained in the corresponding pressure-temperature region, in which diamonds are prepared by PLIIR. In addition, the dependence of the probability for the transformation of graphite to diamond on temperature was investigated and found to be in agreement with the Arrhenius rule.