In-situ pH Measurement at the Electrode/Solution Interface

In this paper a pH microprobe technique was developed to measure in-situ the pH value at the electrode/solution interface. Iridium oxide was used as a pH sensitive material with good response behavior in the measured solutions. The experimental results indicated that the interfacial pH increased with the applied potential, first jumped to a maximum, then slowly decreased at the controlled potential during the electrodeposition process of functional ceramics.

Electrochemical reactions at the electrode/solution interface:Theory and applications to water electrolysis and oxygen reduction

Theoretical simulations on complex electrochemical processes have been developed on the basis of the understanding in electrochemistry,which has benefited from quantum mechanics calculations.This article reviews the recent progress on the theory and applications in electrocatalysis.Two representative reactions,namely water electrolysis and oxygen reduction,are selected to illustrate how the theoretical methods are applied to electrocatalytic reactions.The microscopic nature of these electrochemical reactions under the applied potentials is described and the understanding of the reactions is summarized.The thermodynamics and kinetics of the electrochemical reactions affected by the interplay of the electrochemical potential,the bonding strength and the local surface structure are addressed at the atomic level.

A facile finger-paint physical modification for bilateral electrode/electrolyte interface towards a stable aqueous Zn battery

Since the electrode/electrolyte interface(EEI)is the main redox center of electrochemical processes,proper manipulation of the EEI microenvironment is crucial to stabilize interfacial behaviors.Here,a finger-paint method is proposed to enable quick physical modification of glass-fiber separator without complicated chemical technology to modulate EEI of bilateral electrodes for aqueous zinc-ion batteries(ZIBs).An elaborate biochar derived from Aspergillus Niger is exploited as the modification agent of EEI,in which the multi-functional groups assist to accelerate Zn^(2+)desolvation and create a hydrophobic environment to homogenize the deposition behavior of Zn anode.Importantly,the finger-paint interface on separator can effectively protect cathodes from abnormal capacity fluctuation and/or rapid attenuation induced by H_(2)O molecular on the interface,which is demonstrated in modified MnO_(2),V_(2)O_(5),and KMn HCF-based cells.The as-proposed finger-paint method opens a new idea of bilateral interface engineering to facilitate the access to the practical application of the stable zinc electrochemistry.

NaCl aqueous solution as a novel electrode in a dielectric barrier discharge reactor for highly efficient ozone generation

Ozone(O_(3)) generated by a dielectric barrier discharge(DBD) is widely used in various industrial processes. In this study, NaCl aqueous solution was used as a novel electric power transmission electrode in a DBD reactor(instead of a traditional metal electrode) for highly efficient ozone generation. The results demonstrated that a high O_(3) yield of 242 g k Wh^(-1) with a concentration of 14.6 g m^(-3)O_(3) was achieved. The power transmission mechanism works because NaCl aqueous solution behaves as a capacitor when an alternating pulse voltage below 8 k Hz is used.Compared with the resistance of the discharge barrier and discharge space, the resistance of NaCl aqueous solution can be ignored, which ensures that O_(3) is generated efficiently. It is expected that O_(3) generation using NaCl aqueous solution as a novel electrode in a DBD reactor could be an alternative technology with good application prospects.

Oscillation properties of eigenfunctions for Sturm-Liouville problems with interface conditions via Prufer transformation

A class of Sturm-Liouville problems with discontinuity is studied in this paper.The oscillation properties of eigenfunctions for Sturm-Liouville problems with interface conditions are obtained.The main method used in this paper is based on Prufer transformation,which is different from the classical ones.Moreover,we give two examples to verify our main results.

Exact solution of plane isolated crack normal to a bimaterial interface of infinite extent

This paper presents an exact solution for the transverse interface crack in the plane strain case. The crack is perpendicular to the interface and in one material. The exact complex stress functions are first obtained with some unknown constants. The satisfactions of all boundary conditions are then checked, the condition at infinity is considered and the unknown constants are determined. Further study may focus on the case with different shear moduli and the influence of the large deformation.

Investigation of polysulfone film on high-performance anode with stabilized electrolyte/electrode interface for lithium batteries

Lithium metal has been considered to be the most promising anode material for the new generation of energy-storage system.However,challenges still stand in protecting lithium metal from spontaneous reactions with electrolytes and preventing the dendritic propagation,both of which would lead to undesirable decrease in Coulombic efficiency.Polysulfone(PSf)membrane with high rigidity and free-volume cavities of approximately 0.3 nm was employed to provide a stable interface on the surface of anodic electrode.The isotropic channels were constructed by the interconnected and uniformly distributed free volumes in the polymer matrix,and were expected to be swelled by solvent molecules and anions of lithium salt and to allow Li+ions to pass through onto the electrode surface.As a result,dendrite-free morphology of deposited lithium was observed.The stabilized interface arose from the PSf film was verified by the promoted performances of Cu|Li cells and steady voltage polarization of Li|Li cells.The full cell with PSf coated anode exhibited excellent cyclability(85%capacity retention rate over 400 cycles at 1C)and an outstanding rate capability(117 m Ah g-1 at 5C).The beneficial performances were further verified by the EIS results.This work provides a new strategic idea to settle the dendritic problems of Li metal anodes.

Structure and resistance of concentration polar layer on cation exchange membrane-solution interface

Membrane/solution interface consists of a neutral concentration polar layer(CPL)and a charge layer(CL)under external electrical field,and the neutral CPL can be neglected under high frequency AC electrical field.The relationship of CL thickness e with electrolyte concentration C and fixed ion exchange sites density σ in membrane surface layer can be expressed as e=σ/C.According to this model,the thickness of the CL on Nafion1135 membrane/solution interface(ec)was calculated under different membrane surface charge quantity Q and variable electrolyte concentration C.The membrane/solution interface CL thickness(em)is obviously related with the membrane properties,and decreases dramatically in a higher electrolyte concentration.em values are 76.3 nm and 110.3 nm respectively for Nafion1135 and PE01 ion exchange membrane in 0.05 mol/L H2SO4 solution,and em values for both membrane tend to 2 nm in 2 mol/L H2SO4 solution.For Nafion1135 membrane,the comparison of ec and em gives the result that CL thickness em obtained by resistance measurement fits well with the calculated CPL thickness ec while proton in CL transferred to membrane surface is 14.56×10?10 mol,which corresponds to the fixed exchange group number in a surface layer with a thickness τ=2 nm for Nafion1135 membrane.

Current status and trends of carbon-based electrodes for fully solution-processed perovskite solar cells

Perovskite solar cells(PSCs) have revolutionized photovoltaic research. As a result, a certified power conversion efficiency(PCE) of 25.5% was recorded in late 2020. Although this efficiency is comparable with silicon solar cells;some issues remain partially unsolved, such as lead toxicity, instability of perovskite materials under continuous illumination, moisture and oxygen, and degradation of the metallic counter electrodes. As an alternative to tackle this last concern, carbon materials have been recently used, due to their good electrical and thermal conductivity, and chemical stability, which makes them one of the most promising materials to replace metallic counter electrodes in the fabrication of PSCs. This review highlights the recent advances of carbon-based PSCs, where the carbon electrode(CE) is the main actor.CEs have become very promising candidates for PSCs;they are mainly fabricated using a simple combination of graphite and carbon black powders embedded in a binder matrix, giving a paste that is then solution-processable, resulting in devices with improved quality stability, when compared to metallic electrodes. In this review, CE’s composition is emphasized, since it can give both, high and lowtemperature processed electrodes, compatible with different device configurations. Finally, the tendencies and opportunities to use CE in PSCs devices are presented.

Solution‑Processed Transparent Conducting Electrodes for Flexible Organic Solar Cells with 16.61% Efficiency

Nonfullerene organic solar cells(OSCs)have achieved breakthrough with pushing the efficiency exceeding 17%.While this shed light on OSC commercialization,high-performance flexible OSCs should be pursued through solution manufacturing.Herein,we report a solution-processed flexible OSC based on a transparent conducting PEDOT:PSS anode doped with trifluoromethanesulfonic acid(CF3SO3H).Through a low-concentration and low-temperature CF3SO3H doping,the conducting polymer anodes exhibited a main sheet resistance of 35Ωsq−1(minimum value:32Ωsq−1),a raised work function(≈5.0 eV),a superior wettability,and a high electrical stability.The high work function minimized the energy level mismatch among the anodes,hole-transporting layers and electron-donors of the active layers,thereby leading to an enhanced carrier extraction.The solution-processed flexible OSCs yielded a record-high efficiency of 16.41%(maximum value:16.61%).Besides,the flexible OSCs afforded the 1000 cyclic bending tests at the radius of 1.5 mm and the long-time thermal treatments at 85°C,demonstrating a high flexibility and a good thermal stability.

Diffusion-controlled Adsorption Kinetics of Surfactant at Air/Solution Interface

For the diffusion-controlled adsorption,the expression of dynamic surface adsorption(t)was obtained by solving the diffusion equation.Two cases,i.e.the short and long time limits,were mainly discussed in this paper.From the measured dynamic surface tension of aqueous surfactant sodium dodecyl sulfate(SDS) solutions at25 °C,the adsorption kinetics of SDS at air/solution interface was studied.It was proved that for both of the short and long time limits,the adsorption process of SDS was controlled by diffusion.

Electrocatalytic Activity of Ni/C Electrodes Prepared by Metal Vapor Synthesis For Hydrogen Evolution in Alkaline Solution

The metal vapor synthesis (MVS) methed was used to prepare activatedcarbon supported nickel electrode. The electrocatalytic activity of the electrode forhydrogen evolution reaction(HGR) in alkaline solution was studied. Cathodicpolarization curves showed the electrocatalytic activity of Ni/C electrode prepared byMVS method was higher than that of the one prepared by conventional method.

Stabilization of formamidinium lead iodide perovskite precursor solution for blade-coating efficient carbon electrode perovskite solar cells

Formamidinium lead triiodide(FAPbI_(3))is a research hotspot in perovskite photovoltaics due to its broad light absorption and proper thermal stability.However,quite a few researches focused on the stability of the FAPbI_(3) perovskite precursor solutions.Besides,the most efficient FAPbI_(3) layers are prepared by the spin-coating method,which is limited to the size of the device.Herein,the stability of FAPbI_(3) perovskite solution with methylammonium chloride(MACl)or cesium chloride(CsCl)additive is studied for preparing perovskite film through an upscalable blade-coating method.Each additive works well for achieving a high-quality FAPbI_(3) film,resulting in efficient carbon electrode perovskite solar cells(pero-SCs)in the ambient condition.However,the perovskite solution with MACl additive shows poor aging stability that noα-FAPbI_(3) phase is observed when the solution is aged over one week.While the perovskite solution with CsCl additive shows promising aging stability that it still forms high-quality pureα-FAPbI_(3) perovskite film even the solution is aged over one month.During the solution aging process,the MACl could be decomposed into methylamine which will form some unfavored intermediated phase inducingδ-phase FAPbI_(3).Whereas,replacing MACl with CsCl could effectively solve this issue.Our founding shows that there is a great need to develop a non-MACl FAPbI_(3) perovskite precursor solution for cost-effective preparation of pero-SCs.

IN SITU X-RAY DIFFRACTION CHARACTERIZATION OF SILVER/SOLUTION INTERFACES

In situ x-ray diffraction electrochemical method is used to study the activation of silver electrode in KCl solution and UPD lead on silver electrode surface. We found that the activation makes the silver crystal thicker in (111), and the arrangement of water molecules on the silver electrode surface with UPD lead is partially ordered.

IN-SITU TIME-RESOLVED RAMAN SPECTROSCOPIC STUDIES OF SILVER ELECTRODE IN NaSCN SOLUTION

In-situ time-resolved Raman spectroscopy(TRRS)has been applied on studies of electrochemical adsorption of thiocyanate at silver electrode during potential cycles and potential step.It is shown that some dynamic information about the adsorption and desorption processes can be obtained.

Electrode-compatible fluorine-free multifunctional additive regulating solid electrolyte interphase and solvation structure for high-performance lithium-ion batteries

The rapid development and widespread application of lithium-ion batteries(LIBs) have increased demand for high-safety and high-performance LIBs. Accordingly, various additives have been used in commercial liquid electrolytes to severally adjust the solvation structure of lithium ions, control the components of solid electrolyte interphase, or reduce flammability. While it is highly desirable to develop low-cost multifunctional electrolyte additives integrally that address both safety and performance on LIBs, significant challenges remain. Herein, a novel phosphorus-containing organic small molecule, bis(2-methoxyethyl) methylphosphonate(BMOP), was rationally designed to serve as a fluorine-free and multifunctional additive in commercial electrolytes. This novel electrolyte additive is low-toxicity,high-efficiency, low-cost, and electrode-compatible, which shows the significant improvement to both electrochemical performance and fire safety for LIBs through regulating the electrolyte solvation structure, constructing the stable electrode-electrolyte interphase, and suppressing the electrolyte combustion. This work provides a new avenue for developing safer and high-performance LIBs.

Current advancements on charge selective contact interfacial layers and electrodes in flexible hybrid perovskite photovoltaics

Perovskite-based photovoltaic materials have been attracting attention for their strikingly improved performance at converting sunlight into electricity.The beneficial and unique optoelectronic characteristics of perovskite structures enable researchers to achieve an incredibly remarkable power conversion efficiency.Flexible hybrid perovskite photovoltaics promise emerging applications in a myriad of optoelectronic and wearable/portable device applications owing to their inherent intriguing physicochemical and photophysical properties which enabled researchers to take forward advanced research in this growing field.Flexible perovskite photovoltaics have attracted significant attention owing to their fascinating material properties with combined merits of high efficiency,light-weight,flexibility,semitransparency,compatibility towards roll-to-roll printing,and large-area mass-scale production.Flexible perovskite-based solar cells comprise of 4 key components that include a flexible substrate,semi-transparent bottom contact electrode,perovskite(light absorber layer)and charge transport(electron/hole)layers and top(usually metal)electrode.Among these components,interfacial layers and contact electrodes play a pivotal role in influencing the overall photovoltaic performance.In this comprehensive review article,we focus on the current developments and latest progress achieved in perovskite photovoltaics concerning the charge selective transport layers/electrodes toward the fabrication of highly stable,efficient flexible devices.As a concluding remark,we briefly summarize the highlights of the review article and make recommendations for future outlook and investigation with perspectives on the perovskite-based optoelectronic functional devices that can be potentially utilized in smart wearable and portable devices.

A Review on Engineering Design for Enhancing Interfacial Contact in Solid-State Lithium–Sulfur Batteries

The utilization of solid-state electrolytes(SSEs)presents a promising solution to the issues of safety concern and shuttle effect in Li–S batteries,which has garnered significant interest recently.However,the high interfacial impedances existing between the SSEs and the electrodes(both lithium anodes and sulfur cathodes)hinder the charge transfer and intensify the uneven deposition of lithium,which ultimately result in insufficient capacity utilization and poor cycling stability.Hence,the reduction of interfacial resistance between SSEs and electrodes is of paramount importance in the pursuit of efficacious solid-state batteries.In this review,we focus on the experimental strategies employed to enhance the interfacial contact between SSEs and electrodes,and summarize recent progresses of their applications in solidstate Li–S batteries.Moreover,the challenges and perspectives of rational interfacial design in practical solid-state Li–S batteries are outlined as well.We expect that this review will provide new insights into the further technique development and practical applications of solid-state lithium batteries.

INTERFACE MORPHOLOGIES AND SOLUTE SEGREGATION OF Al-Li ALLOY 8090 DURING UNIDIRECTIONAL SOLIDIFICATION

The solid-liquid interface morphology and solute segregation behaviour of AI-Li alloy 8090 during unidirectional solidification were studied by the liquid metal quenehing method under varied processing conditions.When solidification rate,R<O.13 or>O.75 mm/min (temper- ature gradient,G_L=130℃/cm),the structure revealed of planar or dendritic interface respectively.With the increase of R,the interface morphology becomes cellular from planar gradually,within a narrow range.And the greater the R,the,finer the dendrite.Segregation of element Cu and impurity elements Fe and Si are quite severe,the interface morphology markedly influences on solute segregation.During solidification at coarse dendrite interface, their segregation ratios are rather great and solidified structure is coarse.

Effects of Ca(Y)-Si modifier on interface morphology and solute segregation during directional solidification of an austenite medium Mn steel

The austenite medium Mn steel modified with controlled additions of Ca, Y, Si were directionally solidified using the vertical Bridgman method to study the effects of Ca（Y）-Si modifier on the solid-liquid （S-L） interface morphology and solute segregation. The interface morphology and the C and Mn segregation of the steel directionally solidified at 6.9 μtrn/s were investigated with an image analysis and a scanning electron microscope equipped with energy dispersive X-ray analysis. The 0.5wt% Ca-Si modified steel is solidified with a planar S-L interface. The interface of the 1.0wt% Ca-Si modified steel is similar to that of the 0.5wt% Ca-Si modified steel, but with larger nodes. The 1.5wt% Ca-Si modified steel displays a cellular growth parttern. The S-L interface morphology of the 0.5wt% Ca-Si＋1.0wt% Y-Si modified Mn steel appears as dendritic interface, and primary austenite dendrites reveal developed lateral branching at the quenched liquid. In the meantime, the independent austenite colonies are formed ahead of the S-L interface. A mechanism involving constitutional supercooling explains the S-L interface evolution. It depends mainly on the difference in the contents of Ca, Y, and Si ahead of the S-L interface. The segregation of C and Mn ahead of the S-L interface enhanced by the modifiers is observed.