Heterogeneous Interface Research Articles

High-Performance TiO2/ZrO2/TiO2 Thin Film Capacitor by Plasma-Assisted Atomic Layer Annealing.

Although laminate structures are widely used in electrostatic capacitors, unavoidable heterogeneous interfaces often deteriorate the dielectric properties by impeding film crystallization. In this study, a TiO2/ZrO2/TiO2 (TZT) laminate structure, where upper-TiO2 deposited on the heterogeneous interface was crystallized by plasma-assisted atomic layer annealing (ALA), was investigated. ALA effectively induced the phase transition of the upper-TiO2 from the amorphous or anatase phase to the rutile phase, leading to an increase in the dielectric constant, whereas the ZrO2 blocking interlayer maintained the amorphous phase owing to the extremely localized effect of ALA. Consequently, through the layer-by-layer phase control of ALA, the dielectric constant of the upper-TiO2 was enhanced by 25% by applying ALA, leading to an increase in a capacitance density of 27% of the TZT capacitor, whereas a low leakage current density of ∼10-8 A/cm2 was maintained (at 1 V). In addition, the TZT capacitor on three-dimensional structures (aspect ratio of 5:1) shows a high capacitance density of up to 461 nF/mm2 owing to ALA.

Controllable fiberization engineering of cobalt anchored mesoporous hollow carbon spheres for positive feedback to electromagnetic wave absorption

In order to overcome the limitations of single attenuation mechanism materials in effectively absorbing electromagnetic waves (EMW), meticulous microstructural design of composites and an elevated degree of integration of wave absorbing mechanisms are crucial. Utilizing mesoporous hollow carbon spheres as precursors, PCHM@ComXn (X = Se, S, O) nano-microspheres were synthesized by anchoring cobalt nanoparticles on the surface, controllable encapsulating in continuous fiber structure by electrostatic spinning technique subsequently. The carbon shell-cavity core configuration interspersed with nanoparticles has the advantage of light weight, low density and extensive defects. Abundant heterogeneous interface in carbon fiber offers excellent electrical conductivity and high specific surface area, while a three-dimension conductive network optimizes the transmission loss to incident EMW. The efficient synergy of multiple mechanisms enables PCHM@CoSe2/CNFs to achieve a strong reflection loss of −50.55 dB at a matched thickness of 2.0 mm, while the EABmax value can be extended to a remarkable 6.80 GHz at 2.3 mm, which is considerably superior to fiber samples encapsulating other cobalt-based nanoparticles of the same family. This work provides an innovative direction for the development of high-performance EMW absorbers.

Heterogeneous nucleation interface between NbN(111) and TiN(111) in high-nitrogen austenitic stainless steels: First-principles calculation

Heterogeneous nucleation of NbN induced by TiN inclusions is important to play the role of precipitation strengthening in high-nitrogen austenitic stainless steels. In this work, the atomic structure, interfacial stability, and interfacial fracture toughness of TiN(111)/NbN(111) are investigated based on first-principles calculation. Furthermore, the interfacial bond structure and energy of TiN(111)/NbN(111) are also analyzed with and without Cr doping on the basis of Thermo-Calc phase diagrams. The results indicate that the lattice mismatch between the crystal face of TiN(111) and NbN(111) is lower than 5 %, which reveals that TiN can act as the heterogeneous nucleus for NbN to grow. Besides, the maximum adhesion work at 4.58 J/m2 and the minimum interfacial energy at 1.28 J/m2 are presented on the stacking site of N-Ti TL, which suggests that (Ti, Nb) N phases can precipitate through this interfacial bonding mode. Moreover, from the view of bonding properties on the interface with and without Cr doping, it can be found Cr doping in two layers of the interface can enhance interface stability except for N-Ti TL (2Cr). This work will give promising guidance and theoretical basis for the controllable preparation of high-nitrogen austenitic stainless steels with in-situ precipitated nitride particles.

Redox-Responsive Halogen Bonding as a Highly Selective Interaction for Electrochemical Separations.

Leveraging specific noncovalent interactions can broaden the mechanims for selective electrochemical separations beyond solely electrostatic interactions. Here, we explore redox-responsive halogen bonding (XB) for selective electrosorption in nonaqueous media, by taking advantage of directional interactions of XB alongisde a cooperative and synergistic ferrocene redox-center. We designed and evaluated a new redox-active XB donor polymer, poly(5-iodo-4-ferrocenyl-1-(4-vinylbenzyl)-1H-1,2,3-triazole) (P(FcTS-I)), for the electrochemically switchable binding and release of target organic and inorganic ions at a heterogeneous interface. Under applied potential, the oxidized ferrocene amplifies the halogen binding site, leading to significantly enhanced uptake and selectivity towards key inorganic and organic species, including chloride, bisulfate, and benzenesulfonate, compared to the open-circuit potential or the hydrogen bonding donor analog. Density functional theory calculations, as well as spectroscopic analysis, offer mechanistic insight into the degree of amplification of σ-holes at a molecular level, with selectivity modulated by charge transfer and dispersion interactions. Our work highlights the potential of XB in selective electrosorption by uniquely leveraging noncovalent interactions for redox-mediated electrochemical separations.

Leaf-Inspired Hetero-Structure WS2/WO3 In Situ Embedded on Pomelo Peel Derived Carbon for Supercapacitor and Capacitive Deionization.

Composite materials have occupied a reliable position in electrochemical energy storage and conversion due to their double electric layer and pseudocapacitance. In this work, a leaf-like heterostructure composite, obtained by peeling - carbonizing - in situ sulfuration/oxidation approach for the first time, is investigated as electrode material for electrochemical capacitance behavior. The thin and highly active transition metal WS2 acts as an energetic "blade" to trap free ions, which are then transported across the material through a strong "tendon skeleton" WO3. The derived carbon PPC with a large aspect ratio holds up the overall leaf structure, also as a "warehouse" for ion storage, thus enhancing the conductivity and wettability of the material. The above three (WS2+WO3+PPC) synergistically provide outstanding double-layer capacitance and pseudocapacitance. In particular, the vacancy defects, constructed at the heterogenous interface from WS2-WO3 in situ growth, can still achieve superior ion absorption/desorption ability even under large current density and high concentration brackish solution.

Porous-carbon confined Cu-O-Zn heterointerface for efficient electroreduction of CO2 to syngas with controllable CO/H2 ratios

Electrochemical reduction of CO2 (CO2RR) to syngas is a promising approach for mitigating excessive CO2 emissions and producing liquid fuels and industrial chemicals. However, achieving a suitable CO/H2 ratio in a one-step reaction and a high current density remains a significant challenge. Herein, we prepare Cu-ZnO catalyst with Cu-O-Zn heterogeneous interface derived from metal-organic frameworks (MOFs) to catalyze the conversion of CO2 to syngas. By constructing a Cu-O-Zn heterointerface, the bimetallic electronic configurations are modulated, wherein the reconfiguration of electron density induced by electron delocalization enhances the stabilization of *COOH intermediate and the production of CO. Moreover, the porous carbon derived from MOFs restricts the nanoscale size of bimetallic particles, ensuring abundant Cu-O-Zn heterointerface and exposed active sites, while preventing nanoparticle detachment and aggregation during the reaction process. The obtained catalysts realize high CO selectivity (75.6% of CO Faradaic efficiency) and wide CO/H2 ratio (0.38–3.22) within a relatively narrow potential window and demonstrating excellent stability. This study offers insights into the rational design of high-performance multiphase electrocatalysts.

Engineering fast diffusion channels in metal Sulfide/Selenide heterostructures via confinement effect for high-performance sodium storage

Structural modulation plays a pivotal role in enhancing the energy storage properties of electrochemical hybrids by adjusting their interfacial and electronic characteristics. Nevertheless, facile and effective strategies for tuning the structural properties of these hybrids at the nanoscale remain scarce. In this study, we propose a novel in-situ electrochemically self-driven strategy for embedding FeSe/FeS heterostructures with rich phase boundaries concurrently encapsulated into one-dimensional porous N, S-doped carbon tubes with inner void (FeSe/FeS@SNC). This approach facilitates the creation of heterogeneous interface phases via a simple electrochemical conversion from FeS0.75Se0.25. Notably, the resultant unique one-dimensional porous structure with inner void, along with a highly conductive N/S-co-doped carbon matrix, promotes charge transfer and reinforces structural stability. in-situ/ex-situ microscopic and spectroscopic characterizations, supported by theoretical simulations, validate that FeSe/FeS heterostructures offer rapid electron transport pathways, while the abundant heterojunctions with strong electric fields facilitate ion migration and Na adsorption. As an anode in sodium-ion batteries, the FeSe/FeS@SNC electrdoe exhibits exceptional rate capability (347 mAh/g at 10 A/g) and stable cycling performance (91% capacity retention after 12000 cycles).

Coupling field optimization to improve the thermal transport of Gr/h-BN heterostructure

We perform a numerical evaluation on the multi-physical field coupling effect to improve the interfacial thermal conductivity (ITC) of Gr/h-BN (Graphene/Hexagonal boron nitride) planar heterostructure. The model of Gr/h-BN planar heterostructure (C-BN bonded configuration) is built to investigate the effect of the multifactor coupling effect of different temperatures, N-doping concentration, and single vacancy concentration on the ITC. Finally, the Box-Behnken orthogonal model is established to determine the optimal value of ITC under the coupling effect of multi-physical fields by response surface analysis, and the optimal value of ITC is 14.456 GW m−2 K−1 when the temperature is 673 K, the single vacancy is 2.57 %, and the N-doping is 18.9 %. It implies that the proper coupling configuration is found effective in improving the interfacial thermal conductivity of the Gr/h-BN heterostructure. This work is hoped to help promote the thermal reliability design of graphene heterogeneous interface for related micro/nano semiconductor devices.

Biomass-derived carbon heterostructure composites modified with magnetic iron oxide for excellent EMW-absorbing materials

With the gradual spread of satellite navigation, broadcasting, and communication technologies, the problem of electromagnetic pollution in C- and Ku-band has increased. Electromagnetic wave (EMW) absorbing materials can effectively mitigate this problem. Here, we report the design of a biomass carbon heterostructure for the absorption of EMWs. This design takes advantage of the natural fiber mesh structure of the loofah and the voids, veins, and basal tissues surrounding the fibers. The material is then carbonized to create a radar antenna-like structure of fibers and nanosheets. This improves the material's conductive loss. In addition, modification with magnetic iron oxide in loofah sponges improves the impedance matching of the materials, enhances the magnetic loss, and increases the heterogeneous interface. We found that the maximum effective absorption frequency range of the prepared EMW-absorbing materials is 3.80 GHz, which is mainly concentrated in the C-band and Ku-band, and its maximum RLminvalue is −59.20 dB. The material's ability to absorb EMWs was also verified by simulating the radar cross section (RCS). In conclusion, this work develops a green and efficient composite material for absorbing EMWs and provides new design ideas for the development of EMW-absorbing materials.

Observing and Modeling the Wear Process of Heterogeneous Interface.

Understanding and controlling the wear process of heterogeneous interfaces between soft and hard phases is crucial for designing and fabricating materials, such as improving the wear resistance of particle reinforced metal matrix composites and the accuracy and efficiency of chemical mechanical polishing. However, the wear process can be hardly observed, as interfaces are buried under the surface. Here, we proposed a nanowear test method by combining focused ion beam cutting to expose interfaces, atomic force microscopy to rub against interfaces, and scanning electron microscope to characterize the interface damage. Using this method, three typical wear forms had been observed in Al/SiC composite, i.e., merely matrix wear, particle fracture, and particle pullout. A theoretical model was proposed that revealed that the increasing interfacial friction would induce particle fracture or pullout, depending on the particle edge angle and tip edge angle. This work sheds light on wear control in composites and nanofabrication.

Mo4/3B2Tx induced hierarchical structure and rapid reaction dynamics in MoS2 anode for superior sodium storage

Molybdenum sulfide (MoS2) with large layer distance and high theoretical capacity has been identified as one of the most promising anodes for sodium ion batteries, but the poor intrinsic conductivity and severe structural agglomeration restricted its diffusion kinetic and specific capacity. In this work, the synergistic effect of heterogeneous interface and Na2S adsorption/conversion active sites was employed to construct Mo4/3B2Tx-MoS2@C composites using a self-assembly and calcination strategy. Theoretical calculation and experimental results demonstrated that the charge transfer and interface between Mo4/3B2Tx and MoS2 along with the 3D hydrangea-like structure improved the intrinsic conductivity and provided fast ion diffusion channels, boosting the electrochemical kinetics; while the favorable adsorption of Na2S and weakened Na-S bond at Mo4/3B2Tx-Mo interface optimized the recombination energies of Mo-S bond, accelerating the ion diffusion and enhancing the electrochemical reversibility. In addition, the copious sulfur vacancies provided additional active sites for ion storage, ameliorating the electrochemical capacity. As expected, the novel Mo4/3B2Tx-MoS2@C electrode delivered a satisfactory rate capacity (340.6 mAh g−1 at 1 A g−1) and durable cyclic performance (267.2 mAh g−1 after 600 cycles at 2 A g−1). When paring with Na3V2(PO4)3, the Mo4/3B2Tx-MoS2@C||Na3V2(PO4)3 full cell exhibited high energy densities of 234.0 and 131.7 Wh kg−1 at 215.7 W kg−1 and 4.4 kW kg−1, respectively. The proposed synergistic strategy of heterogeneous interface and Na2S adsorption/conversion active sites provided a new guidance for the rational design of transitional metal sulfide anodes for sodium ion batteries.

Built-in electric field and core-shell structure of the reconstructed sulfide heterojunction accelerated water splitting

The rational design of high-performance bifunctional electrocatalysts for overall water splitting (OWS) is the key to popularize hydrogen production technology. The active metal oxyhydroxide (MOOH) formed after surface self-reconfiguration of transition metal sulfide (TMS) electrocatalyst is often regarded as the "actual catalyst" in oxygen evolution reaction (OER). Herein, an Fe doped CoS2/MoS2 hollow TMS polyhedron (Fe-CoS2/MoS2) with rich Mott-Schottky heterojunction is reported and directly utilized as an OWS electrocatalyst. The spontaneous built-in electric field (BEF) at the heterogeneous interface regulates the electronic structure and D-band center of the catalyst. More importantly, the “TMS-MOOH” core-shell structure obtained in the KOH electrolyte shows enhanced OER properties. And the introduction of Fe ions activates the inert basal plane of MoS2, which greatly steps up the performance of HER. Hence, the preferable Fe-CoS2/MoS2–400 presents superior OER activity (η10 = 178 mV, η100 = 375 mV), HER activity (η10 = 92 mV) and ultra-high stability for 50 h. This work has deeply explored the catalytic mechanism of TMS and provided a new idea for the construction of efficient bifunctional catalysts.

Accelerating overall electrochemical water splitting at the heterogeneous interface of surface crystallized Chiral Amide-bonded CoIIporphyrins

Herein, a series of six chiral-amide bonded CoIIporphyrins containing L/D-alanine, phenylalanine and tryptophan were isolated and characterized. Interestingly, the surface crystallized CoIIporphyrins nanomaterials have the significant increase of the electrochemically catalyzed overall water splitting, and the tunable catalytic activities could be modulated by the enantiomeric isomers and the types of meso-substituted amino acids. Meanwhile, the surface crystallized CoIIporphyrins are stable in a wide range of medias which have provided the new insights of surface functionalization strategies towards enhanced overall water splitting.

Steering bidirectional polysulfide conversion in virtue of interface microenvironment of Ni/porous carbon Mott-Schottky heterojunctions

Originating from the notorious shuttle effect and intrinsically sluggish redox kinetics of polysulfides (especially under the conditions of high sulfur loadings and low electrolytes), the low capacity and sulfur utilization efficiency, unsatisfactory rate performance, and unremarkable cycle performance severely hinder the practical commercialization of lithium-sulfur batteries (LSBs). Furnishing rapid electron transfer and mass diffusion in virtue of interface modulation and nanostructure design is an effective strategy to enhance the activity of catalysts. Herein, a Mott-Schottky heterojunction composed of porous carbon (PC)-supported nickel (Ni) nanoparticles was fabricated on a functionalized carbon nanotube sponge (Ni/PC/FCNTS) via adjusting the geometric structure such as the particle size, aggregation state and pore volume (based on the different solvothermal reaction temperature of the Ni-MOF precursor and the high-temperature pyrolysis process). Transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS) demonstrated the charge redistribution and a self-generated built-in electric field accelerated electron transfer at the heterogeneous interface between Ni and PC. Meanwhile, the high pore volume of Ni/PC/FCNTS-170 provided a reaction space for rapid ion diffusion and sulfur redox process. Benefiting from the synergistic effect, the derived S@Ni/PC/FCNTS-170 cells manifested excellent rate performance with a capacity of 784.2 mAh g-1 at 2 C and a high areal capacity of 8.09 mAh cm-2 with a high sulfur loading of 17.6 mg cm-2 and low electrolyte/sulfur of 11.3 µL mg-1.

Designing multi-functional MoS2/rGO piezocatalysts based on bacteria-catalyst topological interactions and electron pump effects for efficient water disinfection

In catalytic technology, the capability of nanocatalysts to generate reactive species (ROS) and the rapid contact between ROS and target pollutants are critical for the catalytic reaction. Herein, we proposed an effective strategy to construct multi-functional MoS2/rGO piezocatalysts based on bacteria-catalyst topological interactions and electron pump effects, which possessed high carrier separation ability and adhesion to bacteria, ensuring the effective utilization of ROS. Attributed to the unique 3D heterogeneous structure and interface electronic structure, MoS2/rGO could completely inactivate 6.21 log10 cfu mL−1 of E. coli K-12 within 30 min under ultrasonic conditions, significantly faster than pure MoS2. It was demonstrated experimentally and theoretically that the introduction of rGO led to the generation of a large amount of ROS by enhancing the piezoelectric properties and conductivity of MoS2/rGO, while the topological interactions between MoS2/rGO and bacteria facilitated effective bacteria capture, improving the utilization of ROS. Additionally, Kelvin Probe Force Microscopy texting confirmed that rGO acts as an electron pump, effectively attracting electrons from bacterial cells, which disrupted bacterial metabolic processes, increased oxidative stress, and further enhanced the bactericidal effect. The mechanisms of topological interactions and electron pump effects elucidated in this work offer new insights into the design and understanding of efficient bactericidal materials in water purification applications.

Novel nanoporous amorphous/nanocrystalline composite structured RuNiFeCo multicomponent alloys with exceptional catalytic activity for ammonia borane hydrolytic dehydrogenation

The pursuit of high-efficient and cost-effective catalysts for hydrogen generation is imperative to address the energy crisis. Herein, nanoporous RuNiFeCo alloys (np-RuNiFeCo) with high catalytic activity for ammonia borane (AB) hydrolytic dehydrogenation have been prepared by dealloying Fe25NixCo40-xRu5B30 (x = 0–40) high-entropy amorphous alloys with low Ru content. The np-RuNiFeCo are composed of an amorphous/hexagonal close-packed Ru nanocrystalline dual-phase structure and exhibit a uniform nanopore/ligament bicontinuous architecture. The morphology, composition, and AB hydrolysis catalytic properties of the np-RuNiFeCo can be regulated by varying the Ni/Co content in the precursors, and the best catalytic activity with a high turnover frequency value of 148.2 molH2molRu‐1min‐1 and a low apparent activation energy of 25.3 kJmol‐1 was obtained when x = 30. Density functional theory simulations indicate that the presence of Ni, synergizing with Fe and Co, promotes electron transfer to Ru and enhances the adsorption energies of both AB and H2O molecules while reducing the activation barrier for cleaving the H2O molecule, leading to enhanced intrinsic catalytic activity of the alloy. The exceptional catalytic performance of the np-RuNiFeCo arises from the synergy of multiple principal elements, nanoporous morphology, and amorphous/nanocrystalline heterogeneous interface. In addition, the mechanisms of dealloying and nanoporous structure formation have been discussed based on surface diffusion.

Plasma-Engraved Lattice-Matched NiO/NiFe2O4 Heterostructure with Ample Oxygen Vacancies for Efficient Water Electrolysis and Zn-Air Batteries.

Heterogeneous interface and defect engineering offer effective pathways to accelerate oxygen evolution reaction (OER) charge transfer kinetics and motivate optimal intrinsic catalytic activity. Herein, we report the lattice-matched NiO/NiFe2O4 heterostructure with ample oxygen vacancies (Vo-NiO/NiFe2O4) induced by a feasible hydrothermal followed by calcination and plasma-engraving assistant technique, which shows the unique porous microflower arrangement of intertwined nanosheets. Benefitting from the synergetic effects between lattice-matched heterointerface and oxygen vacancies induce the strong electronic coupling, optimized OH-/O2 diffusion pathway and ample active sites, thus-prepared Vo-NiO/NiFe2O4 presents a favorable OER performance with a low overpotential (261 mV @ 10 mA cm-2) and small Tafel slope (39.4 mV dec-1), even surpassing commercial RuO2 catalyst. Additionally, the two-electrode configuration water electrolyzer and rechargeable zinc-air battery assembled by Vo-NiO/NiFe2O4 catalyst show the potential practical application directions. This work provides an innovative avenue for strengthening OER performance toward water electrolysis and Zn-air batteries via the interface and vacancy engineering strategy.

RACER-m leverages structural features for sparse T cell specificity prediction.

Reliable prediction of T cell specificity against antigenic signatures is a formidable task, complicated by the immense diversity of T cell receptor and antigen sequence space and the resulting limited availability of training sets for inferential models. Recent modeling efforts have demonstrated the advantage of incorporating structural information to overcome the need for extensive training sequence data, yet disentangling the heterogeneous TCR-antigen interface to accurately predict MHC-allele-restricted TCR-peptide interactions has remained challenging. Here, we present RACER-m, a coarse-grained structural model leveraging key biophysical information from the diversity of publicly available TCR-antigen crystal structures. Explicit inclusion of structural content substantially reduces the required number of training examples and maintains reliable predictions of TCR-recognition specificity and sensitivity across diverse biological contexts. Our model capably identifies biophysically meaningful point-mutant peptides that affect binding affinity, distinguishing its ability in predicting TCR specificity of point-mutants from alternative sequence-based methods. Its application is broadly applicable to studies involving both closely related and structurally diverse TCR-peptide pairs.

Assessment of the potential structure and nucleation efficacy of multi-component heterogeneous substrate

In recent years, nucleation of multi-component heterogeneous interface structures has attracted increasing attention due to their excellent grain refinement and anti-poisoning capabilities in Al-Si alloy. In this research, a general methodology was proposed to predict the surface structure and meanwhile evaluate the grain refinement efficacy of the multi-component boride nucleants based on a comprehensive experimental and theoretical study of a novel Al-Si alloy refiner, i.e., Al-3.5 Nb-1 V-1B. By using high-resolution electron microscopy, the (Nb, V)B2 particle with a characteristic “core-shell” surface structure was observed, attributed to V adsorption driven by interfacial energy minimization, validated by ab initio calculations. A general interfacial energy-based model was then proposed which predicts the multi-component boride substrate structure, well consistent with the experimental findings. The nucleation potency of different substrates was analyzed in atomic scale and only if the interfacial atomic vibration was considered together with the nucleation-influencing factors (i.e., the lattice mismatch and the anti Si-poisoning effect), the predicted nucleation potency order can agree well with the experimental results. A thermodynamics-kinetics combined analytic model was summarized by coupling the lattice mismatch parameter, the interfacial Si adsorption energy and the interfacial atomic vibration amplitude, which accurately evaluates the multi-component boride grain refiners for the Al-Si alloys.

Constructing heterogeneous interface between Co3O4 and RuO2 with enhanced electronic regulation for efficient oxygen evolution reaction at large current density

Exploring effective strategies for developing new high-efficiency catalysts for water splitting is essential for advancing hydrogen energy technology. Herein, Co3O4/RuO2 heterojunction interface is construct through ion exchange reaction and pyrolysis. The as-synthesized Co3O4/RuO2-4 exhibits outstanding oxygen evolution reaction (OER) activity at the current density of 100 mA cm−2 with a low overpotential of 276 mV, and remarkable stability (maintaining activity for 60 h at 100 mA cm−2). Experimental results and theoretical calculations reveal that the electrons around the heterogeneous interface transferred from RuO2 to Co3O4, resulting in electron redistribution and optimization of energy barriers for OER intermediates. This unique composite catalyst structure offers a new potential for designing efficient oxygen electrocatalysts at large current density.