Interfacial Structure Research Articles

Electrocatalytic Oxygen Reduction Using Metastable Zirconium Suboxide

Strategies for discovery of high‐performance electrocatalysts are important to advance clean energy technologies. Metastable phases such as low temperature or interfacial structures that are difficult to access in bulk may offer such catalytically active surfaces. We report here that the suboxide Zr3O, which is formed at Zr‐ZrO2 interfaces but does not appear in the experimental Zr‐O phase diagram exhibits outstanding oxygen reduction reaction (ORR) performance surpassing that of benchmark Pt/C and most transition metal‐based catalysts. Addition of Fe3C nanoparticles to give a Zr‐Zr3O‐Fe3C/NC catalyst (NC = nitrogen‐doped carbon) gives a half‐wave potential (E1/2) of 0.914 V, outperforming Pt/C and showing only a 3 mV decrease after 20,000 electrochemical cycles. A zinc‐air battery (ZAB) using this cathode material has a high power density of 241.1 mW cm‐2 and remains stable for over 50 days of continuous cycling, demonstrating potential for practical applications. Zr3O demonstrates that interfacial or other phases that are difficult to stabilize may offer new directions for the discovery of high‐performance electrocatalysts.

Electrocatalytic Oxygen Reduction Using Metastable Zirconium Suboxide.

Strategies for discovery of high-performance electrocatalysts are important to advance clean energy technologies. Metastable phases such as low temperature or interfacial structures that are difficult to access in bulk may offer such catalytically active surfaces. We report here that the suboxide Zr3O, which is formed at Zr-ZrO2 interfaces but does not appear in the experimental Zr-O phase diagram exhibits outstanding oxygen reduction reaction (ORR) performance surpassing that of benchmark Pt/C and most transition metal-based catalysts. Addition of Fe3C nanoparticles to give a Zr-Zr3O-Fe3C/NC catalyst (NC = nitrogen-doped carbon) gives a half-wave potential (E1/2) of 0.914 V, outperforming Pt/C and showing only a 3 mV decrease after 20,000 electrochemical cycles. A zinc-air battery (ZAB) using this cathode material has a high power density of 241.1 mW cm-2 and remains stable for over 50 days of continuous cycling, demonstrating potential for practical applications. Zr3O demonstrates that interfacial or other phases that are difficult to stabilize may offer new directions for the discovery of high-performance electrocatalysts.

Atomic-Scale Interface for Pt Nanoparticles on SrTiO3 (001).

The interfacial structure formed by Pt nanoparticles grown epitaxially on a SrTiO3 (001) surface by pulsed laser deposition was studied by X-ray standing-wave (XSW) excited core-level photoelectron emission. The XSW-generated 3D atomic map of the Pt and interfacial oxygens for the oxidized Pt/SrTiO3 interface differs significantly from that of the as-deposited interface. After oxidation, the Pt atoms shifted upward and their atomic occupation at fcc-like sites evolved as the oxidation temperature increased. Interfacial oxygen atoms were differentiated from bulk O atoms by the chemical shift in the binding energy of their 1s electrons. After oxidation, the interfacial oxygen atoms rearranged to form a TiO2 bilayer at the interface. These results provide a more complete description of the strong metal-support interaction process at the interface.

Understanding the Interface Enhancement Mechanisms of CFRP with the Polydopamine-Polyetheramine Interphase at the Molecular Level.

In this work, polydopamine (PDA) and polyetheramine D230 were selected to construct the PDA-D230 interphase between the carbon fiber (CF) and epoxy matrix. Density functional theory (DFT) and molecular dynamics (MD) simulations were performed to explore the interface enhancement mechanisms of a carbon fiber reinforced polymer (CFRP) with the PDA-D230 interphase from the molecular level. The adsorption characteristics of a PDA molecule on the CF surface were investigated using the DFT method. The results show that stronger π-π stacking interactions are formed due to the structure and orientation preference of the PDA molecule. The interfacial structures and properties of CFRP with the PDA-D230 interphase are derived from MD simulations. The PDA-D230 interphase on the CF surface induces stronger interfacial interaction energy, leading to the better load transfer between the CF and epoxy matrix. The existence of the PDA-D230 interphase on the CF surface can decrease the mean-square displacement (MSD) value and the free volume fraction of CFRP, which restricts the movement of epoxy atoms and inhibits the translational and rotational motion of epoxy chains. Compared with the epoxy using pristine CFs as reinforcement, the interfacial shear stress (ISS) of CFRP with the PDA-D230 interphase is improved by 13.1%. Our results provide valuable insights into the interface characteristics of CFRP with the PDA-D230 interphase, which are of great significance for exploring the strengthening mechanisms for CFRPs with the PDA-D230 interphase.

Constructing sulfur-rich interphase to promote the cycle stability of graphite/LiNi0.8Co0.1Mn0.1O2 pouch battery at elevated temperature

Lithium-ion batteries (LIBs) with LiNi0.8Co0.1Mn0.1O2 (NCM811) cathodes have a high energy density, but their long-cycle performance, especially at high temperature, should still be improved due to the instability of the NCM811 cathode-electrolyte interphase. In this work, 2, 2, 2-Trifluoroethyl p-Toluenesulfonate (TPTS) is introduced as a functional film-forming electrolyte additive design to improve the long-term stability of graphite/NCM811 batteries. The preferential redox reactions of TPTS molecules play a pivotal role in fostering the creation of a sulfur-riched interphase, characterized by low impedance. This interphase works to fortify the interfacial structure, effectively inhibiting the dissolution of transition metal ions. Therefore, in comparison to the graphite/NCM811 pouch batteries lacking additive, TPTS enhance the long-cycle capacity retention from 47 % to 80 % after 450 cycles at 45 °C. What's more, TPTS suppresses outgassing and demonstrates enhanced capacity maintenance for the battery even after storage at 60 °C. This work not only demonstrates the stabilizing impacts of TPTS on the electrode-electrolyte interphase and its enhancement of cycling performance at elevated temperatures but also introduces a novel approach for the practical utilization of functional electrolytes matching high-nickel LIBs.

Computationally Efficient and Interface Accurate Dual-Grid Phase-Field Simulation of Turbulent Drop-Laden Flows

Abstract In this work, we develop a dual-grid approach for the direct numerical simulations (DNS) of tur- bulent multiphase flows in the framework of the phase-field method (PFM). With the dual-grid approach, the solution of the Navier-Stokes equations (flow-field) and of the Cahn-Hilliard equa- tion (phase-field) are performed on two different computational grids. In particular, a base grid - fine enough to resolve the flow down to the Kolmogorov scale - is used for the solution of the Navier-Stokes equations, while a refined grid - required to improve the description of small interfacial structures - is used for the solution of the Cahn-Hilliard equation (phase-field method). The proposed approach is validated, and its computational efficiency is evaluated considering the deformation of a drop in a two-dimensional shear flow. Analyzing the computational time and memory usage, we observe a reduction between ≃30% and ≃40% (with respect to the single-grid approach), depending on the grid refinement factor employed for the phase-field variable. The applicability of the approach to a realistic three-dimensional case is also discussed, by focusing on the breakage of a thin liquid sheet inside a turbulent channel flow. Indications on the grid resolution representing a good compromise between accuracy and computational efficiency in drop-laden turbulence are also provided.

Milk fat globule membrane (MFGM) phospholipid - Whey protein interaction characterization and its effect on physicochemical, interfacial properties and evaluation of in vitro digestion of emulsions - Inspired by the MFGM

The interfacial composition of fat globules can change the interfacial structure and further affect the digestive characteristics. In this study, the interaction between whey protein (WP), which is the main protein added in infant formula (IF), and milk fat globule membrane phospholipid (MPL) was investigated from the perspective of simulated fat globule structure, we further characterized the physicochemical properties and the in vitro digestive performance of the emulsions. The results showed that the interaction between MPL and WP changed the secondary and tertiary structures of WP, and formed a dense protective layer at the interface of the fat globule with strong interaction, which improved the emulsification property and physical stability of the emulsion. When MPL: WP was 5:10, the emulsions showed smaller particle size, higher absolute value of zeta-potential and more uniform and stable emulsion state. In addition, during the simulated in vitro digestion of infants, the degree of lipolysis and free fatty acid release content were significantly increased, which improved the fat digestion.

Excellent performance of BiOI/AgEuW2O8 S-Scheme heterojunction for photocatalytic degradation of contaminants under visible light: Experimental and computational studies

A series of xBiOI/AgEuW2O8 (BIAEW-x, x = 1, 2, 3) photocatalysts were prepared by hydrothermal method, further applied for photocatalytic degradation of organic contaminants under the visible light irradiation. The microstructure and photocatalytic properties of the as-synthesized samples were determined by various techniques such as XRD, SEM, TG-DTG, XPS, UV–Vis, ESR, and N2-adsorption. Heterojunction was formed within transition area between BiOI and AgEuW2O8, and the special structure was further validated by the results of XRD and XPS. It was found the composite with 2:1 ratio of BiOI/AgEuW2O8 possessed the highest activity of 99.48 % rhodamine B (RhB) photodegradation which was observed under the optimized conditions (3 h, pH = 5, 60 mg, 30 mg/L). This may be due to the maximum existence of BiOI/AgEuW2O8 heterojunction within the solid, which promotes the generation of the active species during the photocatalytic process. Besides, the newly-formed O–Ag bonds bridging the interface between BiOI (1 0 2) and AgEuW2O8 (0 0 4) were also confirmed according to the DFT calculations, and the electrons and holes increased largely for the interface structure. Moreover, the photodegradation process of RhB promoted by xBiOI/AgEuW2O8 follows first-order kinetic law. Furthermore, the trapping experiments were respectively conducted via addition of different trapping reagents, of which the holes were confirmed as the key active species on photodegradation of RhB over BIAEW-2 under visible light irradiation.

Interfacial molecular structure and orientation evolution of the polystyrene under confinement during annealing revealed by sum frequency generation vibrational spectroscopy

The geometrical confinement directly affects many crucial properties of polymer thin films by interfacial interactions. A key to understanding the role of these interfacial interactions is to specifically probe the confined interface at the molecular level and in situ. However, the direct and nondestructive detection of interfacial polymer structures under confinement is very difficult. In this study, specific interface-sensitive sum frequency generation (SFG) spectroscopy was applied to study the deuterated PS (d8-PS) film confined between hydrogenated poly (methyl methacrylate) (PMMA) films at the molecular level and in situ. The results showed that the ordering/orientation of the PS chain (backbone and phenyl group) evolved at the buried d8-PS/PMMA interface during annealing. The tilt angle of the PS phenyl group increased while the twist angle decreased with elevated annealing temperature. Both overall SFG ssp and ppp intensities decreased after annealing at 433 K for 24 h, indicating that PS chains entangled with or penetrated the PMMA chains at the confined interface. This study qualitatively and quantitatively revealed the interfacial structure and structural evolution of the PS chain confined between PMMA films in situ during annealing, which is beneficial to the molecular-level understanding of the interfacial chain conformational relaxation of polymers under confinement.

Structural basis for the intracellular regulation of ferritin degradation

The interaction between nuclear receptor coactivator 4 (NCOA4) and the iron storage protein ferritin is a crucial component of cellular iron homeostasis. The binding of NCOA4 to the FTH1 subunits of ferritin initiates ferritinophagy—a ferritin-specific autophagic pathway leading to the release of the iron stored inside ferritin. The dysregulation of NCOA4 is associated with several diseases, including neurodegenerative disorders and cancer, highlighting the NCOA4-ferritin interface as a prime target for drug development. Here, we present the cryo-EM structure of the NCOA4-FTH1 interface, resolving 16 amino acids of NCOA4 that are crucial for the interaction. The characterization of mutants, designed to modulate the NCOA4–FTH1 interaction, is used to validate the significance of the different features of the binding site. Our results explain the role of the large solvent-exposed hydrophobic patch found on the surface of FTH1 and pave the way for the rational development of ferritinophagy modulators.

Hot deformation, processing maps, and microstructural evolution of Ti/Ni/Ti layered composites

Ti/Ni/Ti layered composites, which combine the advantages of Ti and Ni, are widely used in sensor and biomedical applications due to their light weight, high strength, high conductivity, good stability and excellent corrosion resistance. However, it is difficult to control the structural parameters, microstructure, and mechanical properties of layered composites during co-deformation processing due to the distinct differences in the crystal structure, mechanical properties, and deformation behavior of Ti and Ni layers. In this paper, the hot deformation, processing maps, and microstructural evolution of Ti/Ni/Ti layered composites during hot deformation processing are investigated through hot compression tests at 550–850 °C/0.001–1.0 s−1, with a reduction of 65%. It is shown that the composites exhibit mainly dynamic recovery or similar dynamic recrystallization characteristics. Combined with the interface structure, processing maps and microstructure, the optimal parameters for Ti/Ni/Ti layered composites are 680–730 °C/0.007–0.015 s−1. During co-deformation, the microstructural evolution of the constituent layers is very complex. The deformation mechanism is mainly dynamic recovery (DRV), or DRV and dynamic recrystallization (DRX) in Ti layer, and work hardening (WH) or DRV in Ni layer.

Positively Charged Amino Acid-Modulated Interfacial Chemistry and Deposition Textures for Highly Reversible Zinc Anodes.

Interfacial active water molecule-induced parasitic reactions and stochastic Zn2+ transport-caused dendrite issue significantly impede the implementation of aqueous Zn-ion batteries. Herein, three positively charged amino acids, namely arginine, histidine, and lysine, were utilized as adsorption-type electrolyte additives to enhance the stability and reversibility of Zn anodes. Combined theoretical and experimental analyses verified that these amino acid cations can synergistically modulate the interfacial microenvironment and promote orientational Zn deposition. The adsorbed amino acid cations reconfigured the interfacial electric double layer structure, forming SO42-- and H2O-poor interfaces, thereby retarding hydrogen evolution and corrosion side reactions. Simultaneously, the preferential adsorption of the amino acid cations at specific facets induced crystallographic orientational Zn deposition along unterminated facets. Three deposition architectures, namely planar texture, subvertical alignment, and vertical erection, were obtained, all effectively inhibiting dendrite formation. Consequently, symmetric cells with the three amino acid cations exhibited high stripping/plating reversibility of over 2000 cycles at 5 mA cm-2. Moreover, MnO2-based full cells exhibited markedly improved stabilities compared with their additive-free counterparts.

Effective photoabsorption and band-structural engineering in CuxO/NiO interfacial photosensor for improved ultraviolet response

Energy bands modulations in thin films heterostructure has offered exceptional leads towards the development of photosensing material. In this work, nanostructured metal oxides interfacial electrode structure has been employed to fabricate a highly sensitive ultraviolet (UV) sensor with high responsivity and detectivity. A unique, simple and cost-effective electrodeposition approach was adopted for the growth of the film samples. The interfacial structural effect and optical energy band modulations on the photo-electronic structure and UV detector performance of the structure have been examined. The films had fair transmissions of the visible light spectrum with CuxO dominance in the resulting bilayer structure and a high absorption peak in the ultraviolet (UV) region. The energy band gap redshifted towards the bilayer structure from 3.74 to 2.67 eV. Charge carriers trapping through surface recombination has been found to reduce from the assistance of ohmic contact formation of the heterostructure. The bilayer film-based photodetector demonstrated enhanced performance with photodetectivity (1.6⨯1011 Jones at 0.068 mWcm−2 power density), attributable to the existence of lower recombination state in the structure, according to the UV sensing study. The study showed that tailoring dissimilar metal oxide semiconducting films to the bilayer (CuxO/NiO) structure can provide excellent UV photodetector performance over single-layer of NiO and CuxO.

Demulsification of W/O emulsions induced by terahertz pulse electric fields-driven hydrogen bond disruption of water molecules

Demulsifying highly stable W/O emulsions, composed of heavy oil and water, is crucial for simplifying crude oil processing, reducing production costs, and mitigating environmental pollution. In these emulsions, aromatic components in the oil phase stack via π-π interactions, while hydrogen bonds stabilize the water phase. This leads to the creation of a strong oil-water interface through electrostatic attraction, ultimately hindering water droplet coalescence and oil-water separation. In this study, a 1.0 THz pulse electric field is introduced to effectively disrupt the hydrogen bond network among water molecules by inducing hydrogen bond resonance. This disruption contributes to increased water mobility in the oil phase, weakened stability of the oil-water interface film, and facilitates efficient water droplet coalescence in the oil phase. The results show that throughout the demulsification process, the average number of hydrogen bonds per water molecule rapidly decreases from 1.41 to 1.08 within 100 ps. The upper and lower limits of hydrogen bond lifetimes decrease by 8.12 ps and 3.24 ps, respectively. This indicates a significant disruption in the stability of hydrogen bonds between water molecules. Concurrently, the terahertz pulse electric field disrupts the initially stable oil-water interface film of the emulsion system, leading to a noteworthy reduction in the oil-water interface tension from 54.3 to 39.2 mN·m−1. The self-diffusion coefficient of water molecules increases from 1.33 to 2.62 Å2·ps−1, signifying that water molecules are more inclined to penetrate the interfacial region between the two phases. Additionally, the terahertz pulse electric field induces alterations in the arrangement of water molecules, resulting in the rearrangement of electrons in the water phase and disrupting the originally stable electrical double layer structure of the oil-water interface. This study provides novel insights into the development of efficient and environmentally friendly electric demulsification technologies, holding significant potential for widespread industrial applications.

Facilitating the dry reforming of methane with interfacial synergistic catalysis in an Ir@CeO2−x catalyst

The dry reforming of methane provides an attractive route to convert greenhouse gases (CH4 and CO2) into valuable syngas, so as to resolve the carbon cycle and environmental issues. However, the development of high-performance catalysts remains a huge challenge. Herein, we report a 0.6% Ir/CeO2−x catalyst with a metal-support interface structure which exhibits high CH4 (~72%) and CO2 (~82%) conversion and a CH4 reaction rate of ~973 μmolCH4 gcat−1 s−1 which is stable over 100 h at 700 °C. The performance of the catalyst is close to the state-of-the-art in this area of research. A combination of in situ spectroscopic characterization and theoretical calculations highlight the importance of the interfacial structure as an intrinsic active center to facilitate the CH4 dissociation (the rate-determining step) and the CH2* oxidation to CH2O* without coke formation, which accounts for the long-term stability. The catalyst in this work has a potential application prospect in the field of high-value utilization of carbon resources.

Interfacial engineering of TiO2@Bi-BiOBr by constructing hierarchical core–shell heterojunction to boost charge transfer for photothermal CO2 reduction

CO2 reduction by a sustainable pathway such as photothermal catalysis is highly demanded currently, high carrier recombination rate still severely limits the performance of photothermal catalysis. Constructing heterojunction interfaces with high exposed area is an effective strategy to solve the problem of carrier recombination. However, fine control of the interface structure is still highly challenging. Herein, Density functional theory (DFT) calculations were constructed to reveal that metallic Bi leads to more densities of states (DOS) generation at the conduction band edge in Bi-BiOBr, which argues that photogenerated electrons are more likely to be delivered to metallic Bi. A TiO2@Bi-BiOBr hollow hierarchical core–shell heterojunction was designed, providing a highly exposed interface and Bi between interfaces. Such structure endows the catalyst with excellent photothermal catalytic performance, achieving a CO yield of 30.4 μmol·h−1·g−1. The highly improved performance is attributed to interfacial thermoelectrons transfer boosted by the construction of TiO2@BiOBr heterojunction as well as metal Bi. And a possible CO2 reduction pathway is proposed, which is consistent with the Carbine pathway. This study provides an exciting idea for the modulation of photoelectron transfer at catalyst interfaces.

A new method for characterizing the atomic composition distribution and interface structure of ultrathin multilayer films using molecular dynamics simulation assisted ARXPS

Characterizing ultrathin multilayer films' atom distribution and interface structure remains challenging. This paper innovatively characterized the chemical composition and distribution of Pt/Co/W ultrathin multilayer films by ARXPS. Molecular dynamics simulated the growth process of films to correspond to that in experiment. The results show that through ARXPS, the actual structure of Pt (2 nm)/Co (t = 0.5–3 nm)/W (2 nm) film could be obtained. For Pt (2 nm)/Co (2 nm)/W (2 nm) film, the actual structure was Pt/Co (1.73 nm)/W (0.78 nm)/WO3 + WO2 (1.48 nm). W at the top layer significantly diffused to the bottom layers, and oxidized W reduced from the surface to the interior of multilayer films. Molecular dynamics simulation confirmed that the interdiffusion degree of Co and W atoms was improved with the increase of Co atoms. The growth modes of Co and W layers were respectively layer-by-layer and island. As the number of Co atoms increased, the relative surface roughness of Co and W layers and the relative interface roughness of Co/W were increased. The in-plane magnetic anisotropy and coercivity were respectively enhanced and decreased due to the change in the surface/interface structure. This paper provides a new idea for analyzing ultrathin multilayer films' atom distribution and interface structure.

Near-zero thermal expansion ZrW2O8/SiO2f wave-transparent composites: Interfacial anti-debonding structures based on polymeric films

The thermal stability of fiber-optic gyroscopes (FOGs) limits their application in harsh environments. This work utilized the unique water-retention properties of hyaluronic acid and the low-temperature cold sintering process combined to fabricate near-zero thermal expansion ZrW2O8/SiO2f composites with thermal resistance. Based on this novel process, the interface debonding of the composites is effectively suppressed and the mechanical and thermal properties of the composites are significantly improved (flexural strength increased by 69.47 %). Moreover, the interface anti-debonding structure reduces the interfacial polarization and reflection loss of the composites, and enhances the wave-transparent properties in the 2–18 GHz frequency range, with a minimum reflection loss of −0.21 dB. Furthermore, the interface anti-debonding structure of the composite provides creep resistance with enhanced sintering densities (increased by 13.61 %). Simultaneously, the composites achieve a controllable coefficient of thermal expansion (CTE) by regulating the liquid phase content and reach near-zero CTE (−0.246 × 10−6 °C−1 [30–300 °C]). Finally, finite element analysis and thermal shock experiments show that the anti-debonding interfacial structure has excellent thermal resistance, and the densest ZrW2O8/SiO2f composites exhibit the best thermal resistance due to minimal thermal strain during thermal shock, which is expected to meet the requirements of FOGs applications.

Performance-enhanced cellulose ternary composite in removing toxic lead ion pollutants: atom-level interfacial structures and pseudo-dynamic trapping process

It is appealing but challenging to modulate interfacial structures and reactivity of biomass composites at the atomic level, due to its importance in guiding experimental synthesis and developing application. In this work, the ternary composite, carbon dots-Mg(OH)2-cellulose (CMCel), was examined by experimental characterizations (XRD, FT-IR, SEM, TEM, and XPS) and theoretical computations, along with its immobilization of heavy metal ion (HMI) Pb(II) from wastewater. Using a facile hydrothermal method, the composite material was prepared. It gives a high removal capacity up to 1623.0 mg g–1 towards Pb(II). Moreover, the removal rate maintains almost 99.5% even after 10-cycle operation. The outstanding performance is attributed to synergetic effects of chemically coupled components in the composite. Specifically, interfacial hydrogen bonds are unraveled by density functional theory calculations and experimental characterizations. The HMI removal is well delineated via a pseudo-dynamic process. The in-depth understanding of interfacial behaviors of CMCel is anticipated to advance the design of novel water treatment agents and improve their removal performance towards HMIs.

The characteristics and mechanical properties of Mo/VC interface structures via first-principles calculations

In the present work, 15 Mo/VC interfaces were investigated using first-principles calculations based on density functional theory. Four possible interface orientations, two terminations, and three stacking sites were considered. The adhesion energy (Wad) and interfacial energy (Eint) of these interface models were computed. The results indicate that the C-terminated hollow-site Mo(110)/VC(111) interface exhibits the highest stability with a larger Wad value of 10.64 J m−2 and the lowest Eint value of 2.98 J m−2, followed by the V-terminated central-site Mo(211)/VC(220) interface. Analysis of the electronic structure reveals the formation of strong polar covalent bonds at these interfaces. Additionally, simulations of tensile fracture processes were performed, demonstrating that at strains reaching 22% and 32%, respectively, the ideal tensile strengths for the C-terminated hollow-site Mo(110)/VC(111) interface and V-terminated central-site Mo(211)/VC(220) interface are ∼26.01 and 35.53 GPa. In particular, in the C-terminated hollow-site Mo(110)/VC(111) interface, fracture occurs in the Mo slabs due to concentrated strain when external strain is applied; meanwhile, uniform strain is observed in both Mo(211) and VC(200) slabs within this system. Notably, the V-terminated central-site Mo(211)/VC (220) interface demonstrates excellent tensile strength as well as toughness. These findings suggest that explaining solely based on adhesion work is insufficient to account for the observed tensile strength at these interfaces.