Sweat-permeable electronic patches by designing threedimensional liquid diodes

Wearable electronics face a significant challenge related to the limited permeability of electronic materials/devices.This issue results in sweat accumulation across the interface of the device and skin following a specific period of use[1−3].Not only does it bring about discomfort for users regarding thermos-physiology,but it also has a detrimental effect on interface adhesion and signal quality,thus hindering exact sig-nal monitoring during prolonged periods[4−6].

Microenvironment and electronic state modulation of Pd nanoparticles within MOFs for enhancing low-temperature activity towards DCPD hydrogenation

Precise control of the local environment and electronic state of the guest is an important method of controlling catalytic activity and reaction pathways.In this paper,guest Pd NPs were introduced into a series of host UiO-67 MOFs with different functional ligands and metal nodes,the microenvironment and local electronic structure of Pd is modulated by introducing bipyridine groups and changing metal nodes(Ce_(6)O_(6) or Zr_(6)O_(6)).The bipyridine groups not only promoted the dispersion Pd NPs,but also facilitated electron transfer between Pd and UiO-67 MOFs through the formation of Pd-N bridges.Compared with Zr6 clusters,the tunability and orbital hybridisation of the 4f electronic structure in the Ce_(6) clusters modulate the electronic structure of Pd through the construction of the Ce-O-Pd interfaces.The optimal catalyst Pd/UiO-67(Ce)-bpy presented excellent low-temperature activity towards dicyclopentadiene hydrogenation with a conversion of>99% and a selectivity of>99%(50℃,10 bar).The results show that the synergy of Ce-O-Pd and Pd-N promotes the formation of active Pd^(δ+),which not only enhances the adsorption of H_(2) and electron-rich C=C bonds,but also contributes to the reduction of proton migration distance and improves proton utilization efficiency.These results provide valuable insights for investigating the regulatory role of the host MOFs,the nature of host-guest interactions,and their correlation with catalytic performance.

In situ atomic-scale tracking of unusual interface reaction circulation and phase reversibility in(de)potassiated alloy-typed anode

Alloy-typed anode materials,endowed innately with high theoretical specific capacity,hold great promise as an alternative to intercalation-typed counterparts for alkali-ion batteries.Despite tremendous efforts devoted to addressing drastic volume change and severe pulverization issues of such anodes,the underlying mechanisms involving dynamic phase evolutions and reaction kinetics have not yet been fully comprehended.Herein,taking antimony(Sb)anode as a representative paradigm,its microscopic operating mechanisms down to the atomic scale during live(de)potassiation cycling are systematically unraveled using in situ transmission electron microscopy.Highly reversible phase transformations at single-particle level,that are Sb←→KSb_(2)←→KSb←→K_5Sb_(4)←→K_(3)Sb,were revealed during cycling.Meanwhile,multiple phase interfaces associated with different reaction kinetics coexisted and this phenomenon was properly elucidated in the context of density functional theory calculations.Impressively,previously unexplored unidirectional circulation of reaction interfaces within individual Sb particle is confirmed for both potassiation and depotassiation.Based on the empirical results,the surface diffusion-mediated potassiation-depotassiation pathways at single-particle level are suggested.This work affords new insights into energy storage mechanisms of Sb anode and valuable guidance for targeted optimization of alloy-typed anodes(not limited to Sb)toward advanced potassium-ion batteries.

Enhanced Electrical Properties of Bi_(2−x)Sb_(x)Te_(3)Nanoflake Thin Films Through Interface Engineering

The structure–property relationship at interfaces is difficult to probe for thermoelectric materials with a complex interfacial microstructure.Designing thermoelectric materials with a simple,structurally-uniform interface provides a facile way to understand how these interfaces influence the transport properties.Here,we synthesized Bi_(2−x)Sb_(x)Te_(3)(x=0,0.1,0.2,0.4)nanoflakes using a hydrothermal method,and prepared Bi_(2−x)Sb_(x)Te_(3)thin films with predominantly(0001)interfaces by stacking the nanoflakes through spin coating.The influence of the annealing temperature and Sb content on the(0001)interface structure was systematically investigated at atomic scale using aberration-corrected scanning transmission electron microscopy.Annealing and Sb doping facilitate atom diffusion and migration between adjacent nanoflakes along the(0001)interface.As such it enhances interfacial connectivity and improves the electrical transport properties.Interfac reactions create new interfaces that increase the scattering and the Seebeck coefficient.Due to the simultaneous optimization of electrical conductivity and Seebeck coefficient,the maximum power factor of the Bi_(1.8)Sb_(0.2)Te_(3)nanoflake films reaches 1.72 mW m^(−1)K^(−2),which is 43%higher than that of a pure Bi_(2)Te_(3)thin film.

Electronic modulation and interface engineering of electrospun nanomaterials‐based electrocatalysts toward water splitting

Nowdays,electrocatalytic water splitting has been regarded as one of the most efficient means to approach the urgent energy crisis and environmental issues.However,to speed up the electrocatalytic conversion efficiency of their half reactions including hydrogen evolution reaction(HER)and oxygen evolution reaction(OER),electrocatalysts are usually essential to reduce their kinetic energy barriers.Electrospun nanomaterials possess a unique one‐dimensional structure for outstanding electron and mass transportation,large specific surface area,and the possibilities of flexibility with the porous feature,which are good candidates as efficient electrocatalysts for water splitting.In this review,we focus on the recent research progress on the electrospun nanomaterials‐based electrocatalysts for HER,OER,and overall water splitting reaction.Specifically,the insights of the influence of the electronic modulation and interface engineering of these electrocatalysts on their electrocatalytic activities will be deeply discussed and highlighted.Furthermore,the challenges and development opportunities of the electrospun nanomaterials‐based electrocatalysts for water splitting are featured.Based on the achievements of the significantly enhanced performance from the electronic modulation and interface engineering of these electrocatalysts,full utilization of these materials for practical energy conversion is anticipated.

First-principles investigation on stability and electronic structure of Sc-dopedθ′/Al interface in Al−Cu alloys

The properties of Sc-dopedθ′(Al_(2)Cu)/Al interface in Al−Cu alloys were investigated by first-principles calculations.Sc-doped semi-coherent and coherentθ′(Al_(2)Cu)/Al interfaces(Sc doped in Al slab(S1 site),Sc doped inθ′slab(S2 site))were modeled based on calculated results and reported experiments.Through the analysis of interfacial bonding strength,it is revealed that the doping of Sc at S1 site can significantly decrease the interface energy and increase the work of adhesion.In particular,the doped coherent interface with Sc at S1 site which is occupied by interstitial Cu atoms has very good bonding strength.The electronic structure shows the strong Al—Cu bonds at the interfaces with Sc at S1 site,and the Al—Al bonds at the interfaces with Sc at S2 site are formed.The formation of strong Al—Cu and Al—Al bonds plays an important role in the enhancement of doped interface strength.

Interface effect on structural and electronic properties of graphdiyne adsorbed on SiO_2 and h-BN substrates:A first-principles study

We use the first-principles calculation method to study the interface effect on the structure and electronic properties of graphdiyne adsorbed on the conventional substrates of rough SiO2 and flat h-BN. For the SiO2 substrate, we consider all possible surface terminations, including Si termination with dangling bond, Si terminations with full and partial hydrogenation, and oxygen terminations with dimerization and hydrogenation. We find that graphdiyne can maintain a flat geometry when absorbed on both h-BN and SiO2 substrates except for the Si termination with partial hydrogenation（Si-H） SiO2 substrate. A lack of surface corrugation in graphdiyne on the substrates, which may help maintain its electronic band character, is due to the weak Van der Waals interaction between graphdiyne and the substrate. Si-H SiO2 should be avoided in applications since a covalent type bonding between graphdiyne and SiO2 will totally vary the band structure of graphdiyne.Interestingly, the oxygen termination with dimerization SiO2 substrate has spontaneous p-type doping on graphdiyne via interlayer charge transfer even in the absence of extrinsic impurities in the substrate. Our result may provide a stimulus for future experiments to unveil its potential in electronic device applications.

Interfacial electronic structure at a metal–phthalocyanine/graphene interface:Copper–phthalocyanine versus iron–phthalocyanine

The energy level alignment of CuPc and FePc on single-layer graphene/Ni（111） （SLG/Ni） substrate was investigated by using ultraviolet and X-ray photoelectron spectroscopy （UPS and XPS）. The highest occupied molecular orbitals （HO- MOs） in a thick layer of CuPc and FePc lie at 1.04 eV and 0.90 eV, respectively, below the Fermi level of the SLG/Ni substrate. Weak adsorbate-substrate interaction leads to negligible interfacial dipole at the CuPc/SLG/Ni interface, while a large interracial dipole （0.20 eV） was observed in the case of FePc/SLG/Ni interface, due to strong adsorbate-substrate coupling. In addition, a new interfacial electronic feature was observed for the first time in the case of FePc on SLG/Ni substrate. This interfacial state can be attributed to a charge transfer from the SLG/Ni substrate to unoccupied orbitals of FePc.

Effect of the stoichiometry on the electronic structure of the Ni(111)/α-Al_2O_3(0001) interface:a first-principles investigation

In this paper first-principles calculations of Ni（111）/α-Al2O3（0001） interfaces have been performed, and are compared with the preceding results of the Cu （111）/α-Al2O3（0001） interface [2004 Phil. Mag. Left. 84 425]. The AI- terminated and O-terminated interfaces have quite different adhesion mechanisms, which are similar to the Cu（111）/α Al2O3（0001） interface. For the O-terminated interface, the adhesion is caused by the strong O-2p/Ni-3d orbital hybridization and ionic interactions. On the other hand, the adhesion nature of the Al-terminated interface is the image-like electrostatic and Ni-Al hybridization interactions, the latter is substantial and cannot be neglected. Charge transfer occurs from Al2O3 to Ni, which is opposite to that in the O=terminated interface. The charge transfer direction for the Al-terminated and O-terminated Ni（111）/α-A1203（0001） interfaces is similar to that in the corresponding Cu（111）/α- Al2O3（0001） interface, but there exist the larger charge transfer quantity and consequent stronger adhesion nature, respectively.

Interface Electronic Structure of Ge/ZnSe(111)

Using linear muffin-tin orbitals method with atomic sphere approximation,the interface electronic structure of Ge/ZnSe(111)has been studied.The density of states,local density of states as well as local partial density of states are presented.The interface electronic structure and the interaction characteristics between interface atoms are analyzed.The results show a significant effect of the interface atomic arrangement on the electronic structures.

Optimizing the electronic spin state and delocalized electron of NiCo_(2)(OH)_(x)/MXene composite by interface engineering and plasma boosting oxygen evolution reaction

The electrocatalytic activity of transition-metal-based compounds is closely related to the electronic configuration.However,optimizing the surface electron spin state of catalysts remains a challenge.Here,we developed a spin-state and delocalized electron regulation method to optimize oxygen evolution reaction(OER)performance by in-situ growth of NiCo_(2)(OH)_(x) using Oswald ripening and coordinating etching process on MXene and plasma treatment.X-ray absorption spectroscopy,magnetic tests and electron paramagnetic resonance reveal that the coupling of NiCo_(2)(OH)_(x) and MXene can induce remarkable spin-state transition of Co^(3+)and transition metal ions electron delocalization,plasma treatment further optimizes the 3 d orbital structure and delocalized electron density.The unique Jahn-Teller phenomenon can be brought by the intermediate spin state(t2 _(g)^(5) e_(g)^(1))of Co^(3+),which benefits from the partial electron occupied egorbitals.This distinct electron configuration(t2_(g)^(5) e_(g)^(1))with unpaired electrons leads to orbital degeneracy,that the adsorption free energy of intermediate species and conductivity were further optimized.The optimized electrocatalyst exhibits excellent OER activity with an overpotential of 268 m V at 10 m A cm^(-2).DFT calculations show that plasma treatment can effectively regulate the d-band center of TMs to optimize the adsorption and improve the OER activity.This approach could guide the rational design and discovery of electrocatalysts with ideal electron configurations in the future.

Effect of Switching on Metal-Organic Interface Adhesion Relevant to Organic Electronic Devices

Considerable efforts are currently being devoted to investigation of metal-organic, organic-organic and organic-inorganic interfaces relevant to organic electronic devices such as organic light emitting diode (OLEDs), organic photovoltaic solar cells, organic field effect transistors (OFETs), organic spintronic devices and organic-based Write Once Read Many times (WORM) memory devices on both rigid and flexible substrates in laboratories around the world. The multilayer structure of these devices makes interfaces between dissimilar materials in contact and plays a prominent role in charge transport and injection efficiency which inevitably affect device performance. This paper presents results of an initial study on how switching between voltage thresholds and chemical surface treatment affects adhesion properties of a metal-organic (Au-PEDOT:PSS) contact interface in a WORM device. Contact and Tapping-mode Atomic Force Microscopy (AFM) gave surface topography, phase imaging and interface adhesion properties in addition to SEM/EDX imaging which showed that surface treatment, switching and surface roughness all appeared to be key factors in increasing interface adhesion with implications for increased device performance.

Electronically Tunable Minimum Component Biquadratic Filters for Interface Circuits

In this paper, two new electronically tunable filter configurations are proposed. The proposed filters operate current-mode (CM), voltage-mode (VM), transimpedance-mode (TIM) and transadmittance-mode (TAM). The first configuration realizes second-order VM band-pass and TAM high-pass filter characteristics from the same configuration. The second one realizes second-order TIM band-pass and CM low-pass filter characteristics from the same configuration. They also use minimum number of electronic components (two capacitors and one active component namely;current controlled current difference transconductance amplifier). The workability of the proposed structures has been demonstrated by simulation results.

Interfacial microstructure and properties of diamond/Cu-xCr composites for electronic packaging applications

Diamond/Cu-xCr composites were fabricated by pressure infiltration process.The thermal conductivities of diamond/Cu-xCr（x = 0.1,0.5,0.8） composites were above 650 W/mK,higher than that of diamond/Cu composites.The tensile strengths ranged from 186 to 225 MPa,and the bonding strengths ranged from 400 to 525 MPa.Influences of Cr element on the thermo-physical properties and interface structures were analyzed.The intermediate layer was confirmed as Cr3C2 and the amount of Cr3C2 increased with the increase of Cr concentration in Cu-xCr alloys.When the Cr concentration was up to 0.5 wt.%,the content of the Cr3C2 layer was constant.As the thickness of the Cr3C2 layer became larger,the composites showed a lower thermal conductivity but higher mechanical properties.The coefficients of thermal expansion（CTE） of diamond/Cu-xCr（x = 0.1,0.5,0.8） composites were in good agreement with the predictions of the Kerner＇ model.

Interface charges boosted ultrafast lithiation in Li_4Ti_5O_12 revealed by in-situ electron holography

It is still a great challenge at present to combine the high rate capability of the electrochemical capacitor with the high electrochemical capacity feature of rechargeable battery in energy storage and transport devices. By studying the lithiation mechanism of Li_4Ti_5O_12 （LTO） using in-situ electron holography, we find that double charge layers are formed at the interface of the insulating Li_4Ti_5O_12 （Li_4） phase and the semiconducting Li_7Ti_5O_12 （Li_7） phase, and can greatly boost the lithiation kinetics. The electron wave phase of the LTO particle is found to gradually shrink with the interface movement, leaving a positive electric field from Li_7 to Li_4 phase. Once the capacitive interface charges are formed, the lithiation of the core/shell particle could be established within 10 s. The ultrafast kinetics is attributed to the built-in interface potential and the mixed Ti3＋/Ti4＋ sites at the interface that could be maximally lowering the thermodynamic barrier for Li ion migration.

Carbon dots regulate the interface electron transfer and catalytic kinetics of Pt-based alloys catalyst for highly efficient hydrogen oxidation

The regulation of interface electron-transfer and catalytic kinetics is very important to design the efficient electrocatalyst for alkaline hydrogen oxidation reaction(HOR).Here,we show the Pt-Ni alloy nanoparticles(PtNi_(2))have an enhanced HOR activity compared with single component Pt catalyst.While,the interface electron-transfer kinetics of PtNi_(2)catalyst exhibits a very wide electron-transfer speed distribution.When combined with carbon dots(CDs),the interface charge transfer of PtNi_(2)-CDs composite is optimized,and then the PtNi_(2)-5 mg CDs exhibits about 2.67 times and 4.04 times higher mass and specific activity in 0.1 M KOH than that of 20%commercial Pt/C.In this system,CDs also contribute to trapping H^(+)and H_(2)O generated during HOR,tuning hydrogen binding energy(HBE),and regulating interface electron transfer.This work provides a deep understanding of the interface catalytic kinetics of Pt-based alloys towards highly efficient HOR catalysts design.

High-mobility two-dimensional electron gases at oxide interfaces:Origin and opportunities

Our recent experimental work on metallic and insulating interfaces controlled by interfacial redox reactions in SrTiO3-based heterostructures is reviewed along with a more general background of two-dimensional electron gas （2DEG） at oxide interfaces. Due to the presence of oxygen vacancies at the SrTiO3 surface, metallic conduction can be created at room temperature in perovskite-type interfaces when the overlayer oxide ABO3 has Al, Ti, Zr, or Hf elements at the B sites. Furthermore, relying on interface-stabilized oxygen vacancies, we have created a new type of 2DEG at the heterointerface between SrTiO3 and a spinel γ-Al2O3 epitaxial film with compatible oxygen ion sublattices. This 2DEG exhibits an electron mobility exceeding 100000 cm2·V-1·s-1, more than one order of magnitude higher than those of hitherto investigated perovskite-type interfaces. Our findings pave the way for the design of high-mobility all-oxide electronic devices and open a route toward the studies of mesoscopic physics with complex oxides.

Effect of SDBS on interfacial electron transfer at the liquid/liquid interface by thin layer method

The effect of an adsorbed anionic surfactant sodium dodecyl benzene sulfonate （SDBS） on electron transfer （ET） reaction between ferricyanide aqueous solution and decamethylferrocene （DMFc） located on the adjacent organic phase was investigated for the first time by thin layer method. The adsorption of SDBS at the interface resulted in a decay in the cathodic plateau current of bimolecular reaction with increasing concentrations of SDBS in aqueous phase. However, the rate constant of electron transfer （ket） increased monotonically as the SDBS concentrations increased from 0 to 200 p, moFL. The experimental results showed that SDBS formed patches on the interface and influenced the structure of electrical double layer. 2009 Xiao Quan Lu. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

Nano-buffer controlled electron tunneling to regulate heterojunctional interface emission

Interface emission from heterojunction is a shortcoming for electroluminescent devices.A buffer layer introduced in the heterojunctional interfaces is a potential solution for the challenge.However,the dynamics for carrier tunneling to control the interface emission is still a mystery.Herein,the low-refractive HfO_(2)with a proper energy band configuration is em-ployed as the buffer layer in achieving ZnO-microwire/HfO_(2)/GaN heterojunctional light-emitting diodes(LEDs).The optic-ally pumped lasing threshold and lifetime of the ZnO microwire are reduced with the introduced HfO_(2)layer.As a result,the interface emission is of blue-shift from visible wavelengths to 394 nm whereas the ultraviolet(UV)emission is en-hanced.To regulate the interface recombination between electrons in the conduction band of ZnO and holes in the valence band of GaN,the tunneling electrons with higher conduction band are employed to produce a higher tunneling current through regulation of thin HfO_(2)film causing blue shift and interface emission enhancement.Our results provide a method to control the tunneling electrons in heterojunction for high-performance LEDs.

TiO_(2)Electron Transport Layer with p-n Homojunctions for Efficient and Stable Perovskite Solar Cells

Low-temperature processed electron transport layer(ETL)of TiO_(2)that is widely used in planar perovskite solar cells(PSCs)has inherent low carrier mobility,resulting in insufficient photogenerated elec-tron transport and thus recombination loss at buried interface.Herein,we demonstrate an effective strategy of laser embedding of p-n homojunctions in the TiO_(2)ETL to accelerate electron transport in PSCs,through localized build-in electric fields that enables boosted electron mobility by two orders of magnitude.Such embedding is found significantly helpful for not only the enhanced crystallization quality of TiO_(2)ETL,but the fabrication of perovskite films with larger-grain and the less-trap-states.The embedded p-n homojunction enables also the modulation of interfacial energy level between perovskite layers and ETLs,favoring for the reduced voltage deficit of PSCs.Benefiting from these merits,the formamidinium lead iodide(FAPbI_(3))PSCs employing such ETLs deliver a champion efficiency of 25.50%,along with much-improved device stability under harsh conditions,i.e.,maintain over 95%of their initial efficiency after operation at maximum power point under continuous heat and illumination for 500 h,as well as mixed-cation PSCs with a champion efficiency of 22.02%and over 3000 h of ambient storage under humidity stability of 40%.Present study offers new possibilities of regulating charge transport layers via p-n homojunction embedding for high performance optoelectronics.