The etching strategy of zinc anode to enable high performance zinc-ion batteries

Zinc-ion batteries(ZIBs)are considered to be one of the most promising candidates to replace lithium-ion batteries(LIBs)due to the high theoretical capacity,low cost and intrinsic safety.However,zinc dendrites,hydrogen evolution reaction,surface passivation and other side reactions will inevitably occur during the charging and discharging process of Zn anode,which will seriously affect the cycle stability of the battery and hinder its practical application.The etching strategy of Zn anode has attracted wide attention because of its simple operation and broad commercial prospects,and the etched Zn anode can effectively improve its electrochemical performance.However,there is no comprehensive review of the etching strategy of Zn anode.This review first summarizes the challenges faced by Zn anode,then puts forward the etching mechanisms and properties of acid,salt and other etchants.Finally,based on the above discussion,the challenges and opportunities of Zn anode etching strategy are proposed.

Anisotropic etching mechanisms of 4H-SiC:Experimental and first-principles insights

Molten-alkali etching has been widely used to reveal dislocations in 4H silicon carbide(4H-SiC),which has promoted the identification and statistics of dislocation density in 4H-SiC single crystals.However,the etching mechanism of 4H-SiC is limited misunderstood.In this letter,we reveal the anisotropic etching mechanism of the Si face and C face of 4H-SiC by combining molten-KOH etching,X-ray photoelectron spectroscopy(XPS)and first-principles investigations.The activation energies for the molten-KOH etching of the C face and Si face of 4H-SiC are calculated to be 25.09 and 35.75 kcal/mol,respectively.The molten-KOH etching rate of the C face is higher than the Si face.Combining XPS analysis and first-principles calculations,we find that the molten-KOH etching of 4H-SiC is proceeded by the cycling of the oxidation of 4H-SiC by the dissolved oxygen and the removal of oxides by molten KOH.The faster etching rate of the C face is caused by the fact that the oxides on the C face are unstable,and easier to be removed with molten alkali,rather than the C face being easier to be oxidized.

Steering surface reconstruction of hybrid metal oxides for efficient oxygen evolution reaction in water splitting and zinc-air batteries

Surface reconstruction yields real active species in electrochemical oxygen evolution reaction(OER)conditions;however,rationally regulating reconstruction in a targeted manner for constructing highly active OER electrocatalysts remains a formidable challenge.Here,an electrochemical activation strategy with selective etching was utilized to guide the reconstruction process of a hybrid cobalt-molybdenum oxide(CoMoO_(4)/Co_(3)O_(4)@CC)in a favorable direction to improve the OER performance.Both in-situ Raman and multiple ex-situ characterization tools demonstrate that controlled surface reconstruction can be easily achieved through Mo etching,with the formation of a dynamically stable amorphous-crystalline heterostructure.Theoretical calculations together with experimental results reveal that the synergistic effects between amorphous CoOOH and crystalline Co_(3)O_(4) are crucial in enhancing the catalytic performance.Consequently,the reconstructed CoMoO_(4)/Co_(3)O_(4)@CC exhibits a low overpotential of 250 mV to achieve a current density of 10 mA cm^(-2) in 1 M KOH,and more importantly it can be practiced in electrolytic water splitting and rechargeable zinc-air batteries devices,achieving ultra-long stability for over 500 and 1200 h,respectively.This work provides a promising route for the construction of high-performance electrocatalysts.

Etching Mechanism of Ti_(3)C_(2)Cl_(2) MXene Phases by CuCl_(2)-Lewis Molten Salt Method

We described a method for obtaining fluorine-free Ti_(3)C_(2)Cl_(2)MXene phases by melting copper in CuCl_(2)instead of aluminum in Ti_(3)AlC_(2).XRD results show that when molten salt CuCl_(2)etches Ti_(3)AlC_(2),it forms an intermediate product Ti_(3)CuC_(2),and then reacts with Ti_(3)CuC_(2)to obtain Ti_(3)C_(2)Cl_(2).The reaction of Ti_(3)AlC_(2)and CuCl_(2)at a temperature of 800℃for 2 h to obtain Ti_(3)C_(2)Cl_(2)with an optimal lamellar structure is shown in SEM results.The pseudopotential plane-wave(PP-PW)method is used to calculate on the electronic structure.The etching mechanism is investigated by the total energies of each substance.The chemical reaction of Ti_(3)AlC_(2)and CuCl_(2)will first become Ti_(3)CuC_(2)and Cu,and then become Ti_(3)C_(2)Cl_(2)during the Lewis acid etching process,which are consistent with the experimental results.

Etching of quartz crystals in liquid phase environment:A review

Quartz crystals are the most widely used material in resonant sensors,owing to their excellent piezoelectric and mechanical properties.With the development of portable and wearable devices,higher processing efficiency and geometrical precision are required.Wet etching has been proven to be the most efficient etching method for large-scale production of quartz devices,and many wet etching approaches have been developed over the years.However,until now,there has been no systematic review of quartz crystal etching in liquid phase environments.Therefore,this article provides a comprehensive review of the development of wet etching processes and the achievements of the latest research in thisfield,covering conventional wet etching,additive etching,laser-induced backside wet etching,electrochemical etching,and electrochemical discharge machining.For each technique,a brief overview of its characteristics is provided,associated problems are described,and possible solutions are discussed.This review should provide an essential reference and guidance for the future development of processing strategies for the manufacture of quartz crystal devices.

Mechanism of K/Ni Etching for Biochar-H_(2)O Gasification

Biomass-H_(2)O gasification is a complex thermochemical reaction,including three processes of volatile removal:homogeneous/heterogeneous reforming,biochar gasification and etching.The rate-determining step is biochar-H_(2)O gasification and etching so the DFT is carried out to see the catalytic role of different metal elements(K/Ni)in the zigzag biochar model.The calculation results show that the gasification of biochar-H_(2)O needs to go through four processes:dissociative adsorption of water,hydrogen transfer(hydrogen desorption,hydrogen atom transfer),carbon dissolution and CO desorption.The energy barrier indicated that the most significant step in reducing the activation energy of K is reflected in the hydrogen transfer step,which is reduced from 374.14 kJ/mol to 152.41 kJ/mol;the catalytic effect of Ni is mainly reflected in the carbon dissolution step,which is reduced from 122.34 kJ/mol to 84.8 kJ/mol.The existence of K causes the edge to have a stronger attraction to H and does not destroy theπbonds of biochar molecules.The destruction ofπbonds is mainly due to the role of H free radicals,while the destruction ofπbonds will lead to easier C-C bond rupture.Ni shows a strong attraction to O in OH,which forms strong Ni-O chemical bonds.Ni can also destroy the aromatic structure directly,making the gasification easier to happen.This study explored the catalytic mechanism of K/Ni on the biochar-H_(2)O gasification at the molecular level and looked forward to the potential synergy of K/Ni,laying a foundation for experimental research and catalyst design.

Recent Advances and Perspectives of Lewis Acidic Etching Route:An Emerging Preparation Strategy for MXenes

Since the discovery in 2011,MXenes have become the rising star in the field of two-dimensional materials.Benefiting from the metallic-level conductivity,large and adjustable gallery spacing,low ion diffusion barrier,rich surface chemistry,superior mechanical strength,MXenes exhibit great application prospects in energy storage and conversion,sensors,optoelectronics,electromagnetic interference shielding and biomedicine.Nevertheless,two issues seriously deteriorate the further development of MXenes.One is the high experimental risk of common preparation methods such as HF etching,and the other is the difficulty in obtaining MXenes with controllable surface groups.Recently,Lewis acidic etching,as a brand-new preparation strategy for MXenes,has attracted intensive attention due to its high safety and the ability to endow MXenes with uniform terminations.However,a comprehensive review of Lewis acidic etching method has not been reported yet.Herein,we first introduce the Lewis acidic etching from the following four aspects:etching mechanism,terminations regulation,in-situ formed metals and delamination of multi-layered MXenes.Further,the applications of MXenes and MXene-based hybrids obtained by Lewis acidic etching route in energy storage and conversion,sensors and microwave absorption are carefully summarized.Finally,some challenges and opportunities of Lewis acidic etching strategy are also presented.

Etching‑Induced Surface Reconstruction of NiMoO_(4) for Oxygen Evolution Reaction

Rational reconstruction of oxygen evolution reaction(OER)precatalysts and performance index of OER catalysts are crucial but still challenging for universal water electrolysis.Herein,we develop a double-cation etching strategy to tailor the electronic structure of NiMoO_(4),where the prepared NiMoO_(4) nanorods etched by H_(2)O_(2) reconstruct their surface with abundant cation deficiencies and lattice distortion.Calculation results reveal that the double cation deficiencies can make the upshift of d-band center for Ni atoms and the active sites with better oxygen adsorption capacity.As a result,the optimized sample(NMO-30M)possesses an overpotential of 260 mV at 10 mA cm−2 and excellent long-term durability of 162 h.Importantly,in situ Raman test reveals the rapid formation of high-oxidation-state transition metal hydroxide species,which can further help to improve the catalytic activity of NiMoO_(4) in OER.This work highlights the influence of surface remodification and shed some light on activating catalysts.

Influence of dry-etching damage on the electrical properties of an AlGaN/GaN Schottky barrier diode with recessed anode

The influences of dry-etching damage on the electrical properties of an AlGaN/GaN Schottky barrier diode with ICPrecessed anode was investigated for the first time. It was found that the turn-on voltage is decreased with the increase of dry-etching power. Furthermore, the leakage currents in the reverse bias region above pinch-off voltage rise as radio frequency（RF） power increases, while below pinch-off voltage, leakage currents tend to be independent of RF power.Based on detailed current–voltage–temperature（I–V –T） measurements, the barrier height of thermionic-field emission（TFE） from GaN is lowered as RF power increases, which results in early conduction. The increase of leakage current can be explained by Frenkel–Poole（FP） emission that higher dry-etching damage in the sidewall leads to the higher tunneling current, while below pinch-off voltage, the leakage is only related to the AlGaN surface, which is independent of RF power.

Recent advances in preparation of metallic superhydrophobic surface by chemical etching and its applications

In the past few decades,inspired by the superhydrophobic surfaces(SHPS)of animals and plants such as lotus leaves,rose petals,legs of water striders,and wings of butterflies,preparing metal materials with metallic SHPS(MSHPS)have attracted great research interest,due to the great prospect in practical applications.To obtain SHPS on conventional metal materials,it is necessary to construct rough surface,followed by modification with low surface energy substances.In this paper,the action mechanism and the current research status of MSHPS were reviewed through the following aspects.Firstly,the model of wetting theory was presented,and then the progress in MSHPS preparation through chemical etching method was discussed.Secondly,the applications of MSHPS in self-cleaning,anti-icing,corrosion resistance,drag reduction,oil-water separation,and other aspects were introduced.Finally,the challenges encountered in the present application of MSHPS were summarized,and the future research interests were discussed.

RDX crystals with high sphericity prepared by resonance acoustic mixing assisted solvent etching technology

In order to obtain high-quality spherical RDX crystal particles,the RDX crystals were suspended in a mixed solvent of cyclohexanone and cyclohexane,subsequently a solvent etching study was carried out under the action of vibration/acoustic flow coupled flow field,which generated by resonance acoustic mixing.The effects of solvent ratio,temperature,acceleration and experiment time on morphology as well as particle size of RDX crystals were studied.Not only were the morphology,particle size distribution and crystal form of RDX crystals determined,but also the thermal decomposition performance and mechanical sensitivity of spherical RDX were examined and discussed.Results indicated that under the process of solvent/non-solvent volume ratio at 1:2,temperature of 40℃,acceleration of 40 g and experiment time of 4 h,α-type RDX crystal with sphericity of 0.92 can be obtained.Furthermore,the median particle size(D_(50))of spherical RDX crystals is 215.8 μm with a unimodal particle size distribution(size span 1.34).For one thing,the thermal decomposition peak temperature of spherical RDX is about 2.5℃ higher than that of raw RDX,and apparent activation energy reaches 444.68 kJ/mol.For another thing,impact sensitivity and friction sensitivity of spherical RDX are 18.18% and 33.33% lower than that of raw RDX,respectively.It demonstrates that safety of spherical RDX under thermal,impact and friction stimuli has been improved.

NH_(3)‑Induced In Situ Etching Strategy Derived 3D‑Interconnected Porous MXene/Carbon Dots Films for High Performance Flexible Supercapacitors

2D MXene(Ti_(3)CNT_(x))has been considered as the most promising electrode material for flexible supercapacitors owing to its metallic conductivity,ultra-high capacitance,and excellent flexibility.However,it suffers from a severe restacking problem during the electrode fabrication process,limiting the ion transport kinetics and the accessibility of ions in the electrodes,especially in the direction normal to the electrode surface.Herein,we report a NH_(3)-induced in situ etching strategy to fabricate 3D-interconnected porous MXene/carbon dots(p-MC)films for high-performance flexible supercapacitor.The pre-intercalated carbon dots(CDs)first prevent the restacking of MXene to expose more inner electrochemical active sites.The partially decomposed CDs generate NH_(3)for in situ etching of MXene nanosheets toward 3D-interconnected p-MC films.Benefiting from the structural merits and the 3D-interconnected ionic transmission channels,p-MC film electrodes achieve excellent gravimetric capacitance(688.9 F g^(-1)at 2 A g^(-1))and superior rate capability.Moreover,the optimized p-MC electrode is assembled into an asymmetric solid-state flexible supercapacitor with high energy density and superior cycling stability,demonstrating the great promise of p-MC electrode for practical applications.

Etching characteristics and surface modification of InGaSnO thin films under Cl_(2)/Ar plasma

Indium gallium tin oxide(IGTO)thin films have the potential for high mobility and lowtemperature processing,which makes them suitable for applications such as display backplanes and high-voltage switching devices.However,very few studies have investigated the plasmaetching characteristics of IGTO and changes in its properties after etching.In this study,the etching characteristics of IGTO were investigated using Cl_(2)/Ar plasma,and changes in surface properties were analyzed.Results showed that the etch rate increased with an increase in the proportion of Cl_(2),with the highest etch rate observed at 69 nm min^(-1)in pure Cl_(2)plasma with a gas flow rate of 100 sccm.Furthermore,increased radio-frequency power caused a rise in the etch rate,while a process pressure of 15 m Torr was optimal.The primary etching mechanism for IGTO thin films under Cl_(2)plasma was a chemical reaction,and an increased work function indicated the occurrence of defects on the surface.In addition,the etching process reduced the surface roughness of Cl_(2)-containing plasma,whereas the etching process in pure Ar plasma increased surface roughness.This study contributes to a better understanding of the plasmaetching characteristics of IGTO and changes in its properties after etching,providing valuable insights for IGTO-based applications.

基于ICP-RIE工艺和共晶键合技术的微引擎

针对便携式设备的电源存在能量密度不够、电池寿命短、回收利用困难以及难以实现小型化等问题,设计了一种氢气作为燃料的微型往复式引擎来替代小型电源,其整体设计尺寸为52 mm×43 mm×4 mm。利用绝缘体上硅(SOI)基板制作了微型往复式引擎的零部件,包括上下盖板、燃烧室、活塞、弹簧和点火装置等;利用电感耦合等离子体-反应离子刻蚀(ICPRIE)得到垂直度接近90°的硅燃烧室、活塞等部件;利用Au-Si共晶键合等关键工艺,保证了上、下盖板与燃烧室等部件之间的气密性。为了验证微引擎的的可行性,搭建了一套测量燃烧压及活塞往复运动的实验装置,测得最大燃烧压约为50 kPa,活塞最大行程长度为1.6 mm,因此其具有广阔的应用前景。

Effect of Different Etching Time on Fabrication of an Optoelectronic Device Based on GaN/Psi

Gallium nitride(GaN)/porous silicon(PSi)film was prepared using a pulsed laser deposition method and 1064 nm Nd:YAG laser for optoelectronic applications and a series of Psi substrates were fabricated using a photoelectrochemical etching method assisted by laser at different etching times for 2.5–15 min at 2.5 min intervals.X-ray diffraction,room-temperature photoluminescence,atomic force microscopy and field emission scanning electron microscopy images,and electrical characteristics in the prepared GaN on the Psi film were investigated.The optimum Psi substrate was obtained under the following conditions:10 min,10 mA/cm^(2),and 24%hydrofluoric acid.The substrate exhibited two highly cubic crystalline structures at(200)and(400)orientations and yellow visible band photoluminescence,and homogeneous pores formed over the entire surface.The pores had steep oval shapes and were accompanied by small dark pores that appeared topographically and morphologically.The GaN/Psi film fabricated through PLD exhibited a high and hexagonal crystallographic texture in the(002)plane.Spectroscopic properties results revealed that the photoluminescence emission of the deposited nano-GaN films was in the ultraviolet band(374 nm)related to GaN material and in the near-infrared band(730 nm)related to the Psi substrate.The topographical and morphological results of the GaN films confirmed that the deposited film contained spherical grains with an average diameter of 51.8 nm and surface roughness of 4.8 nm.The GaN/Psi surface showed a cauliflower-like morphology,and the built-in voltage decreased from 3.4 to 2.7 eV after deposition.The fabricated GaN/Psi film exhibited good electrical characteristics.

Tuning active sites in MoS_(2)-based catalysts via H_(2)O_(2)etching to enhance hydrodesulfurization performance

A H_(2)O_(2)etching strategy was adopted to introduce coordinatively unsaturated sites(CUS)on MoS_(2)-based catalysts for dibenzothiophene(DBT)hydrodesulfurization(HDS).The CUS concentrations on MoS_(2) slabs were finely regulated by changing the concentrations of H_(2)O_(2)solution.With the increasing H_(2)O_(2)concentrations(0.1–0.3 mol/L),The CUS concentrations on MoS_(2) slabs increased gradually.However,the high-concentration H_(2)O_(2)etching(0.5 mol/L)increased the MoOxSy and MoO_(3) contents on MoS_(2) slabs compared to etching with the H_(2)O_(2)concentration of 0.3 mol/L,which led to the less CUS concentration in the sulfided Mo–H-0.5 catalyst than in the sulfided Mo–H-0.3 catalyst.A microstructure-activity correlation indicated that the CUS introduced by H_(2)O_(2)etching on MoS_(2) slabs significantly enhanced DBT HDS.Different Co loadings were further introduced into Mo–H-0.3,which had the most CUS concentration,and the corresponding 0.2-CoMo catalyst with the highest CoMoS content(3.853 wt%)exhibited the highest reaction rate constant of 6.95×10^(−6)mol g^(−1)s^(−1)among these CoMo catalysts.

磁控溅射玫瑰金靶材的刻蚀行为

[目的]磁控溅射玫瑰金膜层相比于电镀工艺具有突出的环保优势,但很少有关于磁控溅射靶材刻蚀行为的研究报道。[方法]以Au85玫瑰金制作平面溅射靶材,进行真空磁控溅射镀膜。研究了靶电流、功率密度、磁场布置等对靶材表面刻蚀行为的影响。[结果]靶电流和功率密度较低时辉光稳定,溅射过程平稳;靶材粒子会优先沿着某个晶面逐层溅射出来,形成阶梯状直线条纹;靶材表面形成V形刻蚀沟槽,刻蚀区斜坡与靶面法向夹角为75°~76°。随着靶电流和功率密度的增大,溅射过程偶有弧光放电现象发生,刻蚀区表面形成乳突状显微形貌;靶电流过高时,靶材在短时间内就会出现熔穿。靶座的磁场布置存在端部效应,使刻蚀槽的深度和宽度存在不均匀的现象。[结论]为提高贵金属平面靶的利用率,应改善磁场布置,并将功率密度控制在出现弧光放电的阈值内。

多层堆叠中晶圆级金金键合的可靠性提升

基于电学互联的贯穿硅通孔技术和高精度金金圆片键合技术,开发了一套可应用于制备三维集成射频(RF)收发系统的工艺,并利用反应离子刻蚀机(RIE)中氧气加六氟化硫的键合前处理技术解决了多层堆叠中键合强度较弱的问题。经过扫描电镜(SEM)观察和分析,键合强度弱确认为芯片贴装过程中晶圆表面沾污所致。传统的湿法前处理有一定的局限性,氧气等离子体方法去污能力较弱,均无法用于去除遗留的沾污。利用反应离子刻蚀机氧气加六氟化硫的前处理方式进行键合前处理,不仅增强了去污能力,而且将旧金表面低活性的金层去除,露出干净、活性高的新金表面,有效提升了金金键合的强度,为多层金金键合提供了一种有效的键合前处理方法。

背腔刻蚀型横向激励薄膜体声波谐振器制备技术研究

随着移动通信技术的快速发展,薄膜体声波滤波器逐渐向高频和大带宽方向发展。该文研究了POI(LiNbO_(3)/SiO_(2)/Si)基片上背腔刻蚀型横向激励薄膜体声波谐振器制作工艺,通过研究POI基IDT光刻、背腔硅刻蚀等工艺,确定了IDT层曝光量和背腔刻蚀等关键工艺参数。研制出的背腔刻蚀型横向激励薄膜体声波谐振器,其谐振频率为4565 MHz,反谐振频率为5035 MHz,机电耦合系数为20.86%。此制备工艺对研究高频、大带宽薄膜体声波滤波器具有重要的参考意义。

灰岩酸蚀裂缝软化区域力学特性与微观特征

碳酸盐岩储层常采用酸化酸压工艺进行改造,酸蚀后岩石表面的微观结构被溶蚀破坏,岩石力学特性发生显著变化,进而影响最终的改造效果。为明确酸蚀对灰岩力学特性和微观孔隙结构变化的影响规律,开展了酸蚀前后灰岩力学特性实验、表面形态特征扫描电镜研究和微观孔隙结构核磁共振表征。结果表明,酸蚀后岩石表面出现了一定厚度的酸蚀软化层,厚度约为11.61μm。值得注意的是,由于酸蚀软化层的存在,灰岩抗压强度、弹性模量与表面硬度均降至酸蚀前的约40%。酸蚀后表层岩石内部产生了大小不一的溶蚀孔洞,并在溶蚀孔洞周边引发应力集中,改变了酸蚀软化层的应力分布。在高闭合应力作用下,溶蚀孔洞易于发生挤压变形或坍塌破坏,这也是酸蚀软化层力学性质改变的主要原因。结合核磁共振T2谱,发现孔径尺寸在1nm~1μm的孔隙数量变化最大,酸液溶蚀改变了灰岩软化层内部的孔隙结构,进而显著影响酸蚀后岩石的力学性质。