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.

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.

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.

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.

One-step Fabrication of Nanoporous Black Silicon Surfaces for Solar Cells using Modified Etching Solution

Currently, a conventional two-step method has been used to generate black silicon （BS） surfaces on silicon substrates for solar cell manufacturing. However, the performances of the solar cell made with such surface generation method are poor, because of the high surface recombination caused by deep etching in the conventional surface generation method for BS. In this work, a modified wet chemical etching solution with additives was developed. A homogeneous BS layer with random porous structure was obtained from the modified solution in only one step at room temperature. The BS layer had low reflectivity and shallow etching depth. The additive in the etch solution performs the function of pH-modulation. After 16-min etching, the etching depth in the samples was approximately 200 nm, and the spectrum-weighted-reflectivity in the range from 300 nm to 1200 nm was below 5%. BS solar cells were fabricated in the production line. The decreased etching depth can improve the electrical performance of solar cells because of the decrease in surface recombination. An efficiency of 15.63% for the modified etching BS solar cells was achieved on a large area, p- type single crystalline silicon substrate with a 624.32-mV open circuit voltage and a 77.88% fill factor.

TREATMENT OF METALS, POLYMER FILMS, AND FABRICS WITHA ONE ATMOSPHERE UNIFORM GLOW DISCHARGE PLASMA(OAUGDP) FOR INCREASED SURFACE ENERGY AND DIRECTIONAL ETCHING

Direct exposure of samples to the active species of air generated by a One Atmosphere Uniform Glow Discharge Plasma (OAUGDP) has been used to etch and to increase the surface energy of metallic surfaces, photoresist, polymer films, and nonwoven fab- rics. The OAUGDP is a non-thermal plasma with the classical characteristics of a DC normal glow discharge that operates in air (and other gases) at atmospheric pres- sure. Neither a vacuum system nor batch processing is necessary. A wide range of applications to metals, photoresist, films, fabrics, and polymeric webs can be accom- modated by direct exposure of the workpiece to the plasma in parallel-plate reactors. This technolopy is simple, it produces effects that can be obtained in no other way at one atmosphere; it generates minimal pollutants or unwanted by-products; and it is suitable for individual sample or online treatment of metallic surfaces, wafers, films, and fabrics. Early exposures of solid materials to the OAUGDP required minutes to produce rela- tively small increases of surface energy. These durations appeared too long for com- mercial application to fast-moving webs. Recent improvements in OAUGDP gas com- position, power density, plasma quality, recireulating gas flow, and impedance match- ing of the power supply to the parallel plate plasma reactor have made it possible to raise the surface energy of a variety of polymeric webs (PP, PET PE etc.) to levels of 60 to 70 dynes/cm with one second of exposure. In air plasmas, the high surface ener- gies are not durable, and fall to 50 dynes/cm after periods of weeks to months. Here, we report the exposure of metallic surfaces, photoresist, polymeric films, and nonwo- ven fabrics made of PP and PET to an impedance matched parallel plate OAUGDP for durations ranging from one second to several tens of seconds. Data will be re- ported on the surface energy, wettability, wickability, and aging effect of polymeric films and fabrics as functions of time of exposure, and time after exposure; the rate and uniformity of photoresist etching; and the production of sub-micron structures by OAUGDP etching at one atmosphere.

Fabrication of Superhydrophobic Aluminum Plate by Surface Etching and Fluorosilane Modification

Superhydrophobic aluminum surfaces with a high water contact angle and low sliding angle on aluminum plate substrate were fabricated by means of surface etching with sodium hydroxide under ultrasonic bathing and then modification with fluorosilane. Scanning electron microscopy（SEM） showed a honeycomb-like structure on aluminum substrate surface after etching under ultrasonic bathing. And the surface was rendered from superhydrophilicity to superhydrophobicity after further modification with fluorosilane.

Improving the surface insulation of epoxy resin by plasma etching

Epoxy resin(EP)tends to accumulate a large amount of charge on its surface when exposed to a high-voltage DC electric field,which leads to a reduction in its insulative performance and an increase in potential safety risks in power systems.To suppress charge accumulation,improve the flashover voltage of the EP,and reduce the risk of gas insulated switchgear(GIS)/gas insulated transmission line(GIL)failure,we used two plasma-etching methods,i.e.,atmospheric-pressure dielectric barrier discharge(DBD)and the atmospheric-pressure plasma jet(APPJ),to modify the surface of the EP.The surface morphology and electrical properties of the modified materials were explored as a function of time.The results show that after DBD treatment,the roughness of the sample increases by 103.9 nm,the conductivity increases by3.9×10^(-18)S,and the flashover voltage increases by 14.4%;after APPJ treatment,the roughness of the sample increases by 223.5 nm,the conductivity increases by 3.4×10^(-17)S,and the flashover voltage increases by 18%.This shows that both plasma-etching methods can improve the insulation properties of materials by improving the surface-charge characteristics.The two methods are compared with each other:the APPJ treatment method is better at improving the surface roughness and electrical properties of materials,and this flexible treatment method has greater potential in industrial applications.

Reduction of Reactive-Ion Etching-Induced Ge Surface Roughness by SF6/CF4Cyclic Etching for Ge Fin Fabrication

An SF6/CF4 cyclic reactive-ion etching （RIE） method is proposed to suppress the surface roughness and to opti- mize the morphology of Ge fin, aiming at the fabrication of superior Ge FinFETs for future CMOS technologies. The surface roughness of the Ge after RIE can be sufficiently reduced by introducing SF6-O2 etching steps into the CF4-O2 etching process, while maintaining a relatively large ratio of vertical etching over horizontal etching of the Ge. As a result, an optimized rms roughness of 0.9nm is achieved for Ge surfaces after the SF6/CF4 cyclic etching with a ratio of greater than four for vertical etching over horizontal etching of the Ge, by using a proportion of 60% for SF6-O2 etching steps.

Surface properties of Al-doped ZnO thin film before and after CF_4/Ar plasma etching

Al-doped ZnO(AZO) is considered as an alternative to transparent conductive oxide materials.Patterning and achieving a stable surface are important challenges in the development and optimization of dry etching processes, which must be overcome for the application of AZO in various devices. Therefore, in this study, the etch rate and surface properties of an AZO thin film after plasma etching using the adaptive coupled plasma system were investigated. The fastest etch rate was achieved with a CF_(4)/Ar ratio of 50:50 sccm. Regardless of the ratio of CF_(4) to Ar,the transmittance of the film in the visible region exceeded 80%. X-ray photoelectron spectroscopy analysis of the AZO thin film confirmed that metal-F bonding persists on the surface after plasma etching. It was also shown that F eliminates O vacancies. Consequently, the work function and bandgap energy increased as the ratio of CF-4 increased. This study not only provides information on the effect of plasma on AZO thin film, but identifies the cause of changes in the device characteristics during device fabrication.

Boring holes in Au nanoplates by active surface etching

In contrast to the conventional etching that makes nanoparticles rounder and our previous sharpening etching mode that causes serrated edges,here,we developed a new boring etching mode that targets the faces of Au nanoplates to make holes.The critical factors are the pre-incubation step with the ligand 2-mercapto-5-benzimidazolecarboxylic acid(MBIA)and the subsequent removal of excess ligands in the solution.Thus,etching is focused onto the few sites with initial loss of ligands,which cannot be quickly replaced.The choice of ligand MBIA is also of importance,as it carries negative charge and repels each other.Its inability of forming a dense layer probably plays a critical role in the site-selectivity for faces,because ligands at the higher curvature edges and corners are expected to have less repulsion.The etching results from the comproportionation reaction between Au3+and Au0 in the nanoplates,where Br-coordination to Au and the extra stabilization from cetyltrimethylammonium bromide(CTAB)are essential.We believe that the ability of boring holes is an important tool for future synthetic designs.

Anodic Etching Surface Treatment and Antibacterial Properties of Ti-Cu

This study used an anodic etching(AE)method to construct a hierarchical rough surface on the surface of the Cu-bearing antibacterial titanium alloy,Ti-xCu(x=3,5,7 wt%),a three-dimensional structure with nested micro-/submicro-pores and internal cavities,which is conducive to the adhesion and growth of bone cells.After AE treatment,with increase of the Cu content in the alloy,the surface of Ti-Cu alloy became sharper,with more fine micropores and internal cavities,thus increasing the surface area.The results indicated that the AE/Ti-Cu alloy exhibited good antibacterial properties and had the effect of inhibiting bacterial biofilm formation.AE treatment could increase the Cu ions release of Ti-Cu alloy in saline,and the higher the Cu content in the alloy,the more Cu ions release,resulting in stronger antibacterial performance of the alloy.AE/Ti-Cu alloy showed excellent biocompatibility,similar to the pure Ti.Therefore,anodic etching is a safe and effective surface treatment method for Ti-Cu alloy,with good clinical application prospects.

Chemical etching process of copper electrode for bioelectrical impedance technology

In order to obtain bioelectrical impedance electrodes with high stability, the chemical etching process was used to fabricate the copper electrode with a series of surface microstructures. By changing the etching processing parameters, some comparison experiments were performed to reveal the influence of etching time, etching temperature, etching liquid concentration, and sample sizes on the etching rate and surface microstructures of copper electrode. The result shows that the etching rate is decreased with increasing etching time, and is increased with increasing etching temperature. Moreover, it is found that the sample size has little influence on the etching rate. After choosing the reasonable etching liquid composition （formulation 3）, the copper electrode with many surface microstructures can be obtained by chemical etching process at room temperature for 20 rain. In addition, using the alternating current impedance test of electrode-electrode for 24 h, the copper electrode with a series of surface microstructures fabricated by the etching process presents a more stable impedance value compared with the electrocardiograph （ECG） electrode, resulting from the reliable surface contact of copper electrode-electrode.

Osteoblast Behavior on Hierarchical Micro-/Nano-Structured Titanium Surface

In the present work, osteoblast behavior on a hierarchical micro-/nano-structured titanium surface was investigated. A hi- erarchical hybrid micro-/nano-structured titanium surface topography was produced via Electrolytic Etching （EE）. MG-63 cells were cultured on disks for 2 h to 7 days. The osteoblast response to the hierarchical hybrid micro-/nano-structured titanium surface was evaluated through the osteoblast cell morphology, attachment and proliferation. For comparison, MG-63 cells were also cultured on Sandblasted and Acid-etched （SEA） as well as Machined （M） surfaces respectively. The results show signifi- cant differences in the adhesion rates and proliferation levels of MG-63 cells on EE, SLA, and M surfaces. Both adhesion rate and proliferation level on EE surface are higher than those on SLA and M surfaces. Therefore, we may expect that, comparing with SLA and M surfaces, bone growth on EE surface could be accelerated and bone formation could be promoted at an early stage, which could be applied in the clinical practices for immediate and early-stage loadings.

Superhydrophobic surface of Mg alloys:A review

In the present review,the formation of superhydrophobic(SHP)structures on the surface of Mg alloys was investigated.Different methods including hydrothermal technique,chemical and electrochemical deposition,conversion and polymer coating,and etching routes were discussed.The superhydrophobicity could form on the surface of Mg alloys by the application of different chemical,electrochemical,and physical methods followed by the immersion of these alloys in the solution containing modifying agents including fatty acids or long-chain molecules.The formed morphology,composition,and contact angle were reported and the effect of synthesis route on these characteristics was reviewed.

Fabrication and Optical Properties of Silicon Nanowires Arrays by Electroless Ag-catalyzed Etching

In order to realize ultralow surface reflectance and broadband antireflection effects which common pyramidal textures and antireflection coatings can't achieve in photovoltaic industry,we used low-cost and easy-made Ag-catalyzed etching techniques to synthesize silicon nanowires(Si NWs) arrays on the substrate of single-crystalline silicon.The dense vertically-aligned Si NWs arrays are fabricated by local oxidation and selective dissolution of Si in etching solution containing Ag catalyst.The Si NWs arrays with 3 μm in depth make reflectance reduce to less than 3% in the range of 400 to 1000 nm while reflectance gradually reached the optimum value with the increasing of etching time.The antireflection of Si NWs arrays are based on indexgraded mechanism:Si NWs arrays on a subwavelength scale strongly scatter incident light and have graded refractive index that enhance the incidence of light in usable wavelength range.However,surface recombination of Si NWs arrays are deteriorated due to numerous dangling bonds and residual Ag particles.

A Multi-Scale Study on Silicon-Oxide Etching Processes in C_4F_8/Ar Plasmas

A multi-scale numerical method coupled with the reactor,sheath and trench model is constructed to simulate dry etching of SiO_2 in inductively coupled C_4F_8 plasmas.Firstly,ion and neutral particle densities in the reactor are decided using the CFD-ACE＋ commercial software.Then,the ion energy and angular distributions（IEDs and IADs） are obtained in the sheath model with the sheath boundary conditions provided with CFD-ACE＋.Finally,the trench profile evolution is simulated in the trench model.What we principally focus on is the effects of the discharge parameters on the etching results.It is found that the discharge parameters,including discharge pressure,radio-frequency（rf） power,gas mixture ratios,bias voltage and frequency,have synergistic effects on IEDs and IADs on the etched material surface,thus further affecting the trench profiles evolution.

An in Vitro Investigation of Acid Etching Treatment Prior to Post and Core Cementation and Teeth Fracture Resistance

In order to investigate how to enhance the teeth fracture resistance after the post and core treatment, an in vitro study was conducted to measure the fracture resistance of endodontically treated teeth restored with cast post and core with two kinds of surface treatment technology and acid etching preparation on the dentinal surface. Sixty-four recently extracted human single-rooted first premolars were endodontically treated and sectioned approximately 1.5 mm above the cementoenamel junction to remove the coronal portion. Each specimen received a cast post, core build-up and a metal alloy crown restoration. All teeth were randomly divided into the smooth surface post, core repair group, the sand blasting surface post, and core repair group, each group was divided into 10 s, 30 s, 60 s acid corrosion treatment group and control group. In acid test groups, an acid etching solution was applied for 10, 30 and 60 seconds, respectively, to the root canal wall surface. Each specimen was embedded in acrylic resin block and tested in an electronic universal testing machine. Fracture loads results showed that canal acid etching could increase teeth fracture resistance strength both in smooth groups and sandblasting group, and achieved the best effect when acid etching for 30 s. Sand spray treatment on the surface of the cast metal post can improve the flexural strength of the teeth after postcrown restoration. Acid etching on the root canal wall surfaces and sand spray treatment on the surface of the cast metal post can improve the flexural strength of the root after post-crown restoration. Therefore, these two methods could be used to strengthen the tooth fracture resistance, and maintain the long-term therapeutic effect of cast post and core restoration.

Characterization and chemical surface texturization of bulk ZnTe crystals grown by temperature gradient solution growth

Using tellurium as a solvent, we grew ZnTe ingots of 30 mm in diameter and 70 mm in length by a temperature gradient solution growth method. Hall tests conducted at 300 K indicated that the as-grown ZnTe exhibits p-type conductivity, with a carrier concentration of approximately 10^14cm^-3, a mobility of approximately 300 cm^2·V·s^-1, and a resistivity of approximately 10^2 Ω·cm. A simple and effective method was proposed for chemical surface texturization of ZnTe using an HF：H2O2：H2O etchant. Textures with the sizes of approximately 1μm were produced on {100}, {110}, and { 111}zn surfaces after etching. The etchant is also very promising in crystal characterization because of its strong anisotropic character and Te-phase selectivity.

Study on Surface Treatments on CdSe Wafers

The surface treatments on CdSe wafers were studied by means of SEM,XPS and micro-current test instrument.The relations between electrical properties of CdSe wafers and surface topography,composition and structure were analyzed.The results show that the change of surface composition by etching is beneficial to decrease leakage current.Meanwhile,the increase of oxygen on surface caused by passivation can largely decrease leakage current.When passivating time is 40 min,the wafers surface appears smooth and compact,which will decrease the density of surface state,the optimal electrical property of the wafer is therefore obtained.