Restructuring of well-defined Pt-based electrode surfaces under mild electrochemical conditions

Since the 1980s,single-crystal Pt electrodes with well-defined surface structures have been deemed stable under mild electrochemical conditions(e.g.,in the potential region of electric double layers,underpotential deposition of hydrogen,or mild hydrogen evolution/OH adsorption)and have served as model electrodes for unraveling the structure-performance relation in electrocatalysis.With the advancement of in situ electrochemical microscopy/spectroscopy techniques,subtle surface restructuring under mild electrochemical conditions has been achieved in the last decade.Surface restructuring can considerably modify electrocatalytic properties by generating/destroying highly active sites,thereby interfering with the deduction of the structure-performance relation.In this review,we summarize recent progress in the restructuring of well-defined Pt(-based)electrode surfaces under mild electrochemical conditions.The importance of the meticulous structural characterization of Pt electrodes before,during,and after electrochemical measurements is demonstrated using CO adsorption/oxidation,hydrogen adsorption/evolution,and oxygen reduction as examples.The implications of present findings for correctly identifying the reaction mechanisms and kinetics of other electrocatalytic systems are also briefly discussed.

Abnormal IR Spectra of CO Adsorbed on the Surface of Glass Carbon Electrode Modified with Polypyrrole Film with Platinum Microparticles

Abnormal IR spectra of CO adsorbed at the surface of glass carbon electrode modified with polypyrrole film with Pt microparticles are reported.

Triboelectric nanogenerator based on electrodeposited Ag octahedral nano-assemblies

The tremendous potential of triboelectric generators-TENGs for converting mechanical energy into electrical energy places them as one of the most promising energy harvesting technologies. In this work, the fabrication of enhanced performance TENGs using Ag octahedron nano-assemblies on ITO as electrodes significantly increases the electric charge collection of the induced tribocharges. Thereby, nanostructured electrical contacts coated with Ag macroscale nano-assemblies with octahedral features were obtained by the electrodeposition technique on flexible PET/ITO substrates. Consequently, the nanostructured triboelectric generator-TENG exhibited 65 times more maximum output power, and almost 10 times more open circuit output voltage than that of a TENG with non-nanostructured contacts passing from μW to m W capabilities, which was attributed to the increment of intrinsic interface states due to a higher effective contact area in the former. Likewise, output performances of TENGs also displayed an asymptotic behavior on the output voltage as the operating frequency of the mechanical oscillations increased, which is attributed to a decrement in the internal impedance of the device with frequency. Furthermore, it is shown that the resulting electrical output power can successfully drive low power consumption electronic devices. On that account, the present research establishes a promising platform which contributes in an original way to the development of the TENGs technology.

Surface Modification of AB_2 and AB_5 Hydrogen Storage Alloy Electrodes by the Hot-Charging Treatment

The effect of the hot-charging treatment on the performance of AB(2) and AB(5) hydrogen storage alloy electrodes was investigated. The result showed that the treatment can markedly improve the voltage plateau ratio (VPR), the high rate discharge ability (HRDA), the diffusion coefficient of hydrogen DH and the discharge capacity of the AB2 hydrogen storage alloy electrode. The SEM analysis showed that the hot-charging treatment brings about a Ni-rich surface due to the dissolution of Zr oxides. It is also very helpful for the improvement of the kinetic properties of AB2 hydrogen storage alloy electrode because the microcracking of the surface results in fresh surface. This can be the basic modification treatment for NiMH battery used in electric vehicles (EVs) in the future. But for AB(5) type alloys, the treatment has the disadvantage of impairing the comprehensive electrochemical properties, because the surface of the alloy may be corroded during the treatment. The mechanism of the surface modification of the electrode is also proposed.

Study on Glow Discharge Plasma Used in Polyester Surface Modification

To achieve an atmospheric pressure glow discharge（APGD）in air and modify the surface of polyester thread using plasma,the electric field distribution and discharge characteristics under different conditions were studied.We found that the region with a strong electric field,which was formed in a tiny gap between two electrodes constituting a line-line contact electrode structure,provided the initial electron for the entire discharge process.Thus,the discharge voltage was reduced.The dielectric barrier of the line-line contact electrodes can inhibit the generation of secondary electrons.Thus,the transient current pulse discharge was reduced significantly,and an APGD in air was achieved.We designed double layer line-line contact electrodes,which can generate the APGD on the surface of a material under treatment directly.A noticeable change in the surface morphology of polyester fiber was visualized with the aid of a scanning electron microscope（SEM）.Two electrode structures-the multi-row line-line and double-helix line-line contact electrodes-were designed.A large area of the APGD plasma with flat and curved surfaces can be formed in air using these contact electrodes.This can improve the efficiency of surface treatment and is significant for the application of the APGD plasma in industries.

Influences of ceria and yttrium on properties of D127 surfacing electrode

The coating of D127, a surfacing electrode, was added ceria （ CeO2 ） and yttrium （Y） for possible enhanced electrode properties. The method of orthogonal test was adopted. The coating with different amount of CeO2 and Y was pressed. The hardness of surfacing layer was carried on by hardness tester, microstracture was investigated by metallograph, and the content of rare earths was analyzed by X-ray energy dispersive spectrometer. The results show that the of deposited metal can be effectively made fine,accordingly, the hardness and the wear-resistanee of deposited metal are also raised. But the addition amount of the rare-earth should be proper. The deposited metal microstructure is the finest and the most homogeneous when the addition amount of CeO2 is 2 wt.% and Y 1.2 wt.% , and the hardness of the surfacing layer is the highest.

Derivatized Electrodes in the Electroanalysis of Pyrimethamine/2-Sulfanilamido-3-Methoxypyrazine （Metakelfin） and Lumefantrine/Artemeter （Coartem）

In this paper, the surface of the carbon graphite working electrode has been modified using pyrimethamine/2-sulfanilamido-3-methoxypyrazine （metakelfin） and lumefantrine/artemeter （coartem）-potent antimalarials. The electrochemical profiles of the surface modified electrodes have been studied using cyclic voltammetry. The results indicate that the metakelfin and lumefantrine/artemeter （coartem） have redox active moieties with the oxidation and reduction peaks for pyrimethamine/2-sulfanilamido-3-methoxypyrazine （metakelfin） modified electrode occurring at 0.510 V and 0.315 V, and that for lumefantrine/artemeter （coartem） occurring at 0.510 V and 0.300 V. Bentonite, a clay montmorrilonite with octahedral and tetrahedral sites which can undergo isomorphous substitution and other interactions was also used modify the electrode surface. The bentonite modified electrode was then used to study metakelfin and lumefantrine/artemeter （coartem）. It was observed that the redox properties of metakelfin and lumefantrine/artemeter （coartem） did not change significantly on the bentonite host matrix. It was observed that the redox activity of artemeter was totally inhibited on the bentonite matrix. Interaction of pyrimethamine/2-sulfanilamido-3-methoxypyrazine （metakelfin） and lumefantrine/artemeter （coartem） modified electrodes with selected biomolecules （methionine, arginine, leucine, tyrosine）, isonicotinic acid and acetyl salicyclic acid is also reported.

Electrosynthesis of H_(2)O_(2)via two-electron oxygen reduction over carbon-based catalysts:From microenvironment control to electrode/reactor design

The electrochemical production of hydrogen peroxide(H_(2)O_(2))by the two-electron oxygen reduction(2e^(-)ORR)process has the advantages of high safety,low energy consumption,and environmental friendliness.For 2e^(-)ORR,the catalyst/electrode is the key component as it strongly affects catalytic performance and cost.Carbon materials have the advantages of high electronic conductivity,good structural stability,easy control of nanostructures,and low cost.Therefore,it has been regarded as a promising catalyst/electrode material for the electrosynthesis of H_(2)O_(2)via 2e^(-)ORR.In addition,studies have also considered the optimization of the liquid/gas interface by tuning the electrode surface,electrolyte pH,and reactor configurations for further improving the activity and selectivity of catalysts.In this review,we provide an in-depth discussion of the recent research on the carbon-based electrocatalysts for 2e^(-)ORR,especially in terms of microenvironment tuning,catalyst/electrode interface engineering,and reactor design for achieving stable and efficient production of H_(2)O_(2).The challenges that we are still facing and the future development prospects will then be concluded,which we believe should help the future development in this field.

Non-invasive transcutaneous electrical stimulation in the treatment of overactive bladder

We reviewed the literature on transcutaneous electrical nerve stimulation(TENS)used as a therapy for overactive bladder(OAB)symptoms,with a particular focus on:stimulation site,stimuli parameters,neural structures thought to be targeted,and the clinical and urodynamic outcomes achieved.The majority of studies used sacral or tibial nerve stimulation.The literature suggests that,whilst TENS therapy may have neuromodulation effects,patient are unlikely to benefit to a significant extent from a single application of TENS and indeed clear benefits from acute studies have not been reported.In long-term studies there were differences in the descriptions of stimulation intensity,strategy of the therapy,and positioning of the electrodes,as well as in the various symptoms and pathology of the patients.Additionally,most studies were uncontrolled and hence did not evaluate the placebo effect.Little is known about the underlying mechanism by which these therapies work and therefore exactly which structures need to be stimulated,and with what parameters.There is promising evidence for the efficacy of a transcutaneous stimulation approach,but adequate standardisation of stimulation criteria and outcome measures will be necessary to define the best way to administer this therapy and document its efficacy.

Experimental Study on High Electrical Breakdown of Water Dielectric

By means of a coaxial apparatus, microsecond charging have been carried out with ferent ethylene glycol concentrations of ethylene pressurized water breakdown experiments with different surface roughness of electrodes and difglycol/water mixture. The experimental results about the breakdown stress and the effective time are presented. The breakdown stress is normalized to the situation that the effective time is transformed to 1 μs and analyzed. The conclusions are as follows： （1） the breakdown stress formula is modified to E = 0.561MA^-1/10teff^-1/^NP^1/8 ;（2） the coefficient M is significantly increased by surface polishing and ethylene glycol additive; （3） it is accumulative for the capacity of improving electrical breakdown strength for surface polishing, ethylene glycol additive, and pressurization, of which pressurization is the most effective method; （4） the highest stress of 235.5 kV/cm is observed in ethylene glycol/water mixture with an ethylene glycol concentration of 80% at a hydrostatic pressure of 1215.9 kPa and is about one time greater than that in pure water at constant pressure; （5） for pressurization and surface polishing, the primary mechanism to improve the breakdown strength of water dielectric is the increase in the breakdown time delay. Research results indicate great potential in the application of the high power pulse conditioning system of water dielectric.

Development of two-port surface acoustic wave resonator with Al/Au electrodes for gas sensing

Simple and efficient surface acoustic wave （SAW） two-port resonators with low insertion loss and high Q-values on ST-X quartz substrate using a corrosion-proof A1/Au-stripe electrode structure are developed for gas sensing. It was composed of two shorted grating reflectors and adjacent intedigital transducers （IDT）, and an active metal film in the cavity between the IDTs for the sensitive film coating. The devices are expected to provide good protection towards metal electrode for gas sensors application in chemically reactive environments. Excellent device performance as low insertion loss, high Q factor and single-mode are achieved by carefully selecting the metallic electrode thickness, cavity length and acoustic aperture. Prior to fabrication, the coupling of modes （COM） model was performed for device simulation to determine the optimal design parameters. The fabricated single-mode SAW resonator at operation frequency of 300 MHz range exhibits matched insertion loss of ~6.5 dB and loaded Q factor in the 3000 range. Using the fabricated resonator as the feedback element, a duaresonator-oscillator with excellent frequency stability （0.1 ppm） was developed and evaluated experimentally, and it is significant for performance improvement of SAW gas sensor.

Nonlinear Vibration of the Flexoelectric Nanoplate with Surface Elastic Electrodes Under Active Electric Loading

This paper mainly studies the effects of surface elastic electrodes and electric loading on the nonlinear vibration of flexoelectric nanoplate.The governing equations are derived based on the von Karman type strain-displacement relations and the flexoelectricity theory.The nonlinear vibration equation is solved by an approximate method.Numerical results reveal that the surface elastic electrodes and the length-width ratio of flexoelectric nanoplate have a more significant effect on the nonlinear resonant frequency of simply-supported nanoplate than that of the all-edge-clamped nanoplate.Meanwhile,the effect of the graphene electrode on the nonlinear resonant frequency is more notable than that of the A1 electrode.Additionally,the applied electric loading can significantly affect the nonlinear resonant frequency of the flexoelectric nanoplate.For the nanoplates with different boundary conditions,the applied electric loading has different effects on the nonlinear resonant frequency.This study has certain research significance in the structure design and examination of the flexoelectric nanoplate with electrodes.

Ultrathin Zn-free anode based on Ti_(3)C_(2)T_(x) and nanocellulose enabling high-durability aqueous hybrid Zn-Na battery with Zn2+/Na+co-intercalation mechanism

With low cost and high safety,aqueous zinc-based batteries have received considerable interest.Nevertheless,the excess utilization of zinc metal in the anodes of these batteries reduces energy density and increases costs.Herein,an ultrathin electrode of approximately 6.2μm thick is constructed by coating Ti_(3)C_(2)T_(x)/nanocellulose hybrid onto a stainless steel foil.This electrode is used as the Zn-free anode for aqueous hybrid Zn-Na battery,in which,a concentrated electrolyte is used to improve electrochemical reversibility.The Ti_(3)C_(2)T_(x)/nanocellulose coating is found to improve the electrolyte wettability,facilitate desolvation process of hydrated Zn^(2+) ions,lower nucleation overpotential,improve zinc plating kinetics,guide horizontal zinc plating along the Zn(002)facet,and inhibit parasitic side reactions.It is also found that the Na_(3)V_(2)(PO_(4))_(3) cathode material adopts a highly reversible Zn^(2+)/Na^(+)co-intercalation charge storage mechanism in this system.Thanks to these benefits,the assembled hybrid Zn-Na battery exhibits excellent rate capability,superior cyclability,and good anti-freezing ability.This work provides a new concept of electrode design for electrochemical energy storage.