Local electric field and configuration of CO molecules adsorbed on a nanostructured surface with nanocones

Based on the nanostructured surface model that the （platinum, Pt） nanocones grow out symmetrically from a plane substrate, the local electric field near the conical nanoparticle surface is computed and discussed. On the basis of these results, the adsorbed CO molecules are modelled as dipoles, and three kinds of interactions, i.e. interactions between dipoles and local electric field, between dipoles and dipoles, as well as between dipoles and nanostructured substrate, are taken into account. The spatial configuration of CO molecules adsorbed on the nanocone surface is then given by Monte-Carlo simulation. Our results show that the CO molecules adsorbed on the nanocone surface cause local agglomeration under the action of an external electric field, and this agglomeration becomes more compact with decreasing conical angle, which results in a stronger interaction among molecules. These results serve as a basis for explaining abnormal phenomena such as the abnormal infrared effect （AIRE）, which was found when CO molecules were adsorbed on the nanostructured transition-metal surface.

Regulating local electric field to optimize the energy storage performance of antiferroelectric ceramics via a composite strategy

Electrostatic energy storage technology based on dielectrics is the basis of advanced electronics and high-power electrical systems.High polarization(P)and high electric breakdown strength(Eb)are the key parameters for dielectric materials to achieve superior energy storage performance.In this work,a composite strategy based on antiferroelectric dielectrics(AFEs)has been proposed to improve the energy storage performance.Here,AlN is selected as the second phase for the(Pb_(0.915)Ba_(0.04)La_(0.03))(Zr_(0.65)Sn_(0.3)Ti_(0.05))O_(3)(PBLZST)AFEs,which is embedded in the grain boundaries to construct insulating networks and regulate the local electric field,improving the Eb.Meanwhile,it is emphasized that AFEs have the AFE–FE and FE–AFE phase transitions,and the increase of the phase transition electric fields can further improve the recoverable energy density(Wrec).As a result,the Eb increases from 180 to 290 kV·cm−1 with a simultaneous increase of the phase transition electric fields,magnifying the Wrec to~144%of the pristine PBLZST.The mechanism for enhanced Eb and the phase transition electric fields is revealed by the finite element simulation method.Moreover,the PBLZST:1.0 wt%AlN composite ceramics exhibit favorable temperature stability,frequency stability,and charge–discharge ability,making the composite ceramics a promising candidate for energy storage applications.

Unusual local electric field concentration in multilayer ceramic capacitors

Local electric-field around multitype pores(dielectric pore,interface pore,electrode pore)in multilayer ceramic capacitors(MLCCs)was investigated using Kelvin probe force microscopy combined with the finite element simulation to understand the effect of pores on the electric reliability of MLCCs.Electricfield is found to be concentrated significantly in the vicinity of these pores and the strength of the local electric-field is 1.5e5.0 times of the nominal strength.Unexpectedly,the concentration degree of the pores in the inner electrode is much higher than that in the dielectrics and dielectric-electrode interfaces.Meanwhile,geometry orientations are found to have a remarkable influence on the local electric field strength.The pores act as an insulation degradation precursor via local electric,thermal center,and oxygen vacancies accumulation center.Such unusual local electric field concentration of multitype pores can provide new insights into the understanding of insulation degradation evolution,processing tailoring and design optimization for MLCCs.

Electric field distribution and effective nonlinear AC and DC responses of graded cylindrical composites

The perturbation method is used to study the localization of electric field distribution and the effective nonlinear response of graded composites under an external alternating-current（AC） and direct-current（DC） electric field E app = E 0（1 ＋ sin ωt）.The dielectric profile of the cylindrical inclusions is modeled by function ε i（r） = C k r k（r ≤ a）,where r is the radius of the cylindrical inclusion,and C k,k,a are parameters.In the dilute limit,the local potentials and the effective nonlinear responses at all harmonics are derived.Meanwhile,the general effective nonlinear responses are also derived and compared with the effective nonlinear responses at harmonics under the AC and DC external field.It is found that the effective nonlinear AC and DC responses at harmonics can be calculated by those of the general effective nonlinear of the graded composites under the external DC electric field.Moreover,the obtained local electrical fields show that the electrical field distribution in the cylindrical inclusions is controllable,and the maximum of the electric field inside the cylinder is at its center.

Local field distribution and configuration of CO molecules adsorbed on the nanostructure platinum surface

This paper shows that the local electric field distribution near the nanostructure metallic surface is obtained by solving the Laplace equation, and furthermore, the configuration of CO molecules adsorbed on a Pt nanoparticle surface is obtained by using Monte Carlo simulation. It is found that the uneven local electric field distribution induced by the nanostructure surface can influence the configuration of carbon monoxide （CO） molecules by a force, which drags the adsorbates to the poles of the nanoparticles. This result, together with our results obtained before, may explain the experimental results that the nanostructure metallic surface can lead to abnormal phenomena such as anti-absorption infrared effects.

Laser-induced periodic surface structured electrodes with 45% energy saving in electrochemical fuel generation through field localization

Electrochemical oxidation/reduction of radicals is a green and environmentally friendly approach to generating fuels.These reactions,however,suffer from sluggish kinetics due to a low local concentration of radicals around the electrocatalyst.A large applied electrode potential can enhance the fuel generation efficiency via enhancing the radical concentration around the electrocatalyst sites,but this comes at the cost of electricity.Here,we report about a~45%saving in energy to achieve an electrochemical hydrogen generation rate of 3×10^(16) molecules cm^(–2)s^(–1)(current density:10 mA/cm^(2))through localized electric field-induced enhancement in the reagent concentration(LEFIRC)at laser-induced periodic surface structured(LIPSS)electrodes.The finite element model is used to simulate the spatial distribution of the electric field to understand the effects of LIPSS geometric parameters in field localization.When the LIPSS patterned electrodes are used as substrates to support Pt/C and RuO_(2) electrocatalysts,the η_(10) overpotentials for HER and OER are decreased by 40.4 and 25%,respectively.Moreover,the capability of the LIPSS-patterned electrodes to operate at significantly reduced energy is also demonstrated in a range of electrolytes,including alkaline,acidic,neutral,and seawater.Importantly,when two LIPSS patterned electrodes were assembled as the anode and cathode into a cell,it requires 330 mVs of lower electric potential with enhanced stability over a similar cell made of pristine electrodes to drive a current density of 10 mA/cm^(2).This work demonstrates a physical and versatile approach of electrode surface patterning to boost electrocatalytic fuel generation performance and can be applied to any metal and semiconductor catalysts for a range of electrochemical reactions.

Increases in Lorentz Factor with Dielectric Thickness

For many years, a Lorentz factor of L = 1/3 has been used to describe the local electric field in thin amorphous dielectrics. However, the exact meaning of thin has been unclear. The local electric field Eloc modeling presented in this work indicates that L = 1/3 is indeed valid for very thin solid dielectrics (tdiel ≤ 20 monolayers) but significant deviations from L = 1/3 start to occur for thicker dielectrics. For example, L ≈ 2/3 for dielectric thicknesses of tdiel = 50 monolayers and increases to L ≈ 1 for dielectric thicknesses tdiel > 200 monolayers. The increase in L with tdiel means that the local electric fields are significantly higher in thicker dielectrics and explains why the breakdown strength Ebd of solid polar dielectrics generally reduces with dielectric thickness tdiel. For example, Ebd for SiO2 reduces from approximately Ebd ≈ 25 MV/cm at tdiel = 2 nm to Ebd ≈ 10 MV/cm at tdiel = 50 nm. However, while Ebd for SiO2 reduces with tdiel, all SiO2 thicknesses are found to breakdown at approximately the same local electric field (Eloc)bd ≈ 40 MV/cm. This corresponds to a coordination bond strength of 2.7 eV for the silicon-ion to transition from four-fold to three-fold coordination in the tetrahedral structure.

High resolution and high signal-to-noise ratio imaging with nearfield high-order optical signals

The properties of near-field optics have always been the focus of nano-measurement technology.The 11th order effective nearfield optical signal with an incident laser wavelength of 1,550 nm is obtained using a platinum-coated optical probe(Pt–Si probe).The experimental results show that the local electric field intensity of the Pt–Si probe is nearly 30 times higher than that of silicon probe(Si probe).Therefore,the highest 7th order near-field optical imaging results are obtained with the Pt–Si probe.Further,near-field optical imaging is performed on samples such as gold grids and carbon nanotubes using the Pt–Si probe.The measurement results show that the high-order signal has the characteristics of less background,higher signal-to-noise ratio,and resolution up to 5.7 nm.

A flat-based plasmonic fiber probe for nanoimaging

The difficulty of obtaining high-intensity localized light spots for optical probes leads to their lack of good applications in nanoimaging.Here we demonstrate a Fabry–Pérot resonance flat-based plasmonic fiber probe(FPFP).The simulation results show that the probe can obtain a nanofocusing spot at the tip with the radially polarized mode.The Fabry–Pérot interference structure is used to control the plasmon propagation on the surface of the probe,it effectively improves the local spot intensity at the tip.Furthermore,the experimental results verify that the FPFP(tip curvature radius is 20 nm)prepared by chemical etching method can obtain a nanofocusing spot at the tip.The nanoimaging of the gold slit structure demonstrates the nanoimaging capability of the FPFP,the 36.9 nm slit width is clearly identified by the FPFP.

Synthesis and Photoluminescence Enhancement of Silver Nanoparticles Decorated Porous Anodic Alumina

Silver nanoparticles（Ag NPs） were successfully assembled in porous anodic alumina（AAO） templates via a green silver mirror reaction.The Ag NPs/AAO composite templates then were characterized by field emission scanning electron microscopy（FESEM）,energy-dispersive X-ray microanalysis（EDX）,and X-ray diffraction（XRD）.Furthermore,the photoluminescence（PL） properties were also investigated.Compared with the blank AAO,the PL intensity of Ag NPs/AAO templates are enhanced and the maximum enhancement is 2.58 times.Based on the local electric field enhancement effect,the theoretical values were also deduced,which are basically coincident with the experimental.

MXene辅助调控杂多酸纳米颗粒局部电场增强其锂存储性能

杂多酸(POMs)具有可逆接收/脱除多个锂离子的能力,被认为是具有广泛应用前景的电化学储锂材料.然而,POMs的绝缘特性阻碍了锂离子在其中的快速迁移.鉴于此,我们提出在由Mn和V组成的POMs纳米颗粒周围引入局部电场,通过同步产生的库仑力加速锂离子的迁移.将POMs与MXenes纳米片复合后,界面处的不平衡电荷分布诱导产生了局部电场,使得锂扩散系数提高了250倍.在1.0 mV s的低扫速下,复合材料赝电容贡献高达81.7%.此外,POMs的纳米颗粒可以在MXene纳米片表面致密组装,赋予电极材料高体积容量.由于改善的锂离子传输动力学,POMs/MXenes复合材料与商业活性炭组装的锂离子电容器可输出195.5 W h kg^(-1)的能量密度和3800 W kg^(-1)的功率密度.本研究为高性能电极材料的设计提供了新思路.