Etching Method Research Articles

A facile acid-etching defect-rich leaf-like zeolitic-imidazolate framework adsorbent for simultaneous removal of organic/inorganic phosphorus pollutants from wastewater

Organophosphorus herbicide glyphosate and inorganic phosphate usually coexist in wastewater, leading to water eutrophication and posing risks to human health. In this study, acid-etching defect-rich leaf-like zeolitic-imidazolate framework (ae-ZIF-L) adsorbent was developed by a facile etching method to investigate its simultaneous removal performance of glyphosate and phosphate. Compared to ZIF-L precursor, ae-ZIF-L displayed a maximum adsorption capacity for phosphate and glyphosate of 164.4 mg g–1 and 12.7 mg g–1, respectively. The overall enhanced adsorption performance of ae-ZIF-L was primarily attributed to abundant Zn defects, resulting in higher positive zeta potentials to enhance electrostatic attraction. Notably, in the phosphate/glyphosate coexistence system, ae-ZIF-L has extremely high removal rates of 99.1 % and 90.9 %, while ZIF-L has removal rates of 97.7 % and 39.4 %, respectively. Furthermore, after four adsorption-desorption cycles, the removal rates of phosphate/glyphosate by ae-ZIF-L remained at 84.8 % and 82.5 %, respectively. In conclusion, ae-ZIF-L proved to be an efficient and reusable adsorbent with promising application for the treatment of organic/inorganic phosphorus pollution in wastewater.

Tuning of fluorescence in titanium carbide MXene nanosheets with La3+ ion doping for the recognition of creatinine biomarker in biofluids

There is a strong correlation between the concentration of creatinine in human urine and the overall health of the kidneys. Therefore, there has been a persistent need for a rapid, and cost-effective quantitative method to assay creatinine levels in urine. Herein, green fluorescent La3+ doped titanium carbide nanosheets (La3+-doped Ti3C2 NSs) are fabricated via HF etching method by using Ti3AlC2 as MAX phase material and La(NO3)3 as a doping agent. As synthesized fluorescent La3+-doped Ti3C2 NSs are stable, showing green fluorescence under UV light. The as-synthesized La3+-doped Ti3C2 NSs act as a fluorescent sensor for the sensitive recognition of creatinine biomarker. The La3+-doped Ti3C2 NSs-based fluorescence method showed a fluorescence quenching at emission wavelength 518 nm towards creatinine with a linear range of 0.25–7.5 μM and detection limit of 63.44 nM. The paper strip based on La3+-doped Ti3C2 NSs was developed for the visual identification of creatinine. Furthermore, La3+-doped Ti3C2 NSs were used as probes for imaging of Saccharomyces cerevisiae cells. Also, the as-fabricated La3+-doped Ti3C2 NSs propose a quick response giving a cost-effective analytical strategy for the selective assay of creatinine in biofluids (plasma and urine).

Effect of Ti3C2-MXene size on cell viability of human carcinoma cells

MXene nanoflakes, a new type of transition metal carbides, nitrides, and carbonitrides (named as MXene) have emerged as biocompatible transition metal structures, which illustrate desirable performance for various applications due to their unique physicochemical, and compositional virtues. MXenes are currently expanding their application from optical, chemical, electronic, and mechanical fields towards biomedical areas. In terms of biomedical applications, the biological toxicity of MXenes materials in different forms must be considered inevitably. In this paper, Ti3C2-MXene nanoflakes with different sizes have been prepared by means of wet etching method combined with powerful ultrasonication for exploring the effect in human breast carcinoma cells (MDA-MB-231 Cells) and human thyroid carcinoma cells (GLAG-66 Cells). Clinically representative MDA-MB-231 Cells and GLAG-66 Cells are selected as experimental subjects and their biotoxicities are characterized when exposed to Ti3C2-MXene nanoflakes with different sizes and concentrations. The results show that Ti3C2-MXene nanoflakes with sizes below 200 nm is almost non-toxic to MDA-MB-231 Cells and GLAG-66 Cells at low concentrations, and enhance their bioactivity and proliferation. When the nanoflake size is above 200 nm, Ti3C2-MXene has a significant inhibitory effect on the proliferation of the cells. This phenomenon may be due to the different roles of Ti3C2-MXene materials at different scales in cell proliferation as well as in complex physiological processes. This result is of great significance for material screening and design before biological experiments using Ti3C2-MXene.

Construction of a BiOCl/Bi2O2CO3 S-Scheme Heterojunction Photocatalyst via Sharing [Bi2O2]2+ Slabs with Enhanced Photocatalytic H2O2 Production Performance.

The construction of a close contact interface is key to enhancing the photocatalytic activity in heterojunctions. In the work, the BiOCl/Bi2O2CO3 of sharing [Bi2O2]2+ slabs S-scheme heterojunction was prepared by a HCl in situ etching method. The optimal composite photocatalyst could accomplish sizable productivity of H2O2 to 2562.95 μmol g-1 h-1 under simulated solar irradiation, higher than that of primitive Bi2O2CO3 and BiOCl. Moreover, the synthesized catalysts showed good stability. The band structures of BiOCl and Bi2O2CO3 were determined, confirming the formation of BiOCl/Bi2O2CO3 S-scheme heterojunction The BiOCl/Bi2O2CO3, which obviously improved the separation efficiency of photoinduced carriers and effectively enhanced the redox ability of the photocatalyst. In addition, density functional theory (DFT) calculations were utilized to analyze the electron transfer properties and the constitution of the built-in electric field at the interface of BiOCl and Bi2O2CO3. The photocatalytic reaction process was further researched by electron paramagnetic resonance (EPR), indicating the active species in the photocatalytic production of hydrogen peroxide. Eventually, a feasible S-scheme electron transfer mechanism on the BiOCl/Bi2O2CO3 heterojunction during the photocatalytic H2O2 production process was proposed and discussed. This work provides a reliable strategy for the fine design of the S-scheme heterojunction.

Study on Electrical and Mechanical Properties of Double-End Supported Elastic Substrate Prepared by Wet Etching Process.

Preparing elastic substrates as a carrier for dual-end supported nickel chromium thin film strain sensors is crucial. Wet etching is a vital microfabrication process widely used in producing microelectronic components for various applications. This article combines lithography and wet etching methods to microprocess the external dimensions and rectangular grooves of 304 stainless steel substrates. The single-factor variable method was used to explore the influence mechanism of FeCl3, HCl, HNO3, and temperature on the etching rate, etching factor, and etching surface roughness. The optimal etching parameter combination was summarized: an FeCl3 concentration of 350 g/L, HCl concentration of 150 mL/L, HNO3 concentration of 100 mL/L, and temperature of 40 °C. In addition, by comparing the surface morphology, microstructure, and chemical and mechanical properties of a 304 stainless steel substrate before and after etching treatment, it can be seen that the height difference of the substrate surface before and after etching is between 160 μm and -70 μm, which is basically consistent with the initial design of 0.2 mm. The results of an XPS analysis and Raman spectroscopy analysis both indicate that the surface C content increases after etching, and the corrosion resistance of the surface after etching decreases. The nano-hardness after etching increased by 26.4% compared to before, and the ζ value decreased by 7%. The combined XPS and Raman results indicate that the changes in surface mechanical properties of 304 stainless steel substrates after etching are mainly caused by the formation of micro-nanostructures, grain boundary density, and dislocations after wet etching. Compared with the initial rectangular substrate, the strain of the I-shaped substrate after wet etching increased by 3.5-4 times. The results of this study provide the preliminary process parameters for the wet etching of a 304 stainless steel substrate of a strain measuring force sensor and have certain guiding significance for the realization of simple steps and low cost of 304 stainless steel substrate micro-nano-processing.

Atomic Depth Image Transfer of Large-Area Optical Quartz Materials Based on Pulsed Ion Beam.

The high-efficiency preparation of large-area microstructures of optical materials and precision graphic etching technology is one of the most important application directions in the atomic and near-atomic-scale manufacturing industry. Traditional focused ion beam (FIB) and reactive ion etching (RIE) methods have limitations in precision and efficiency, hindering their application in automated mass production. The pulsed ion beam (PIB) method addresses these issues by enhancing ion beam deflection to achieve high-resolution material removal on a macro scale, which can reach the equivalent removal resolution of 6.4 × 10-4 nm. Experiments were conducted on a quartz sample (10 × 10 × 1 mm) with a specific pattern mask using the custom PIB processing device. The surface morphology, etching depth, and roughness were measured post-process. The results demonstrated that precise control over cumulative sputtering time yielded well-defined patterns with expected average etching depths and surface roughness. This confirms the PIB technique's potential for precise atomic depth image transfer and its suitability for industrial automation, offering a significant advancement in microfabrication technology.

Low temperature coefficient of frequency AlN Lamb wave resonator using groove structure between interdigital transducers

The lithographically tunable and small size features of Lamb wave resonators (LWRs) take a bright future for their use in high frequency narrow band filters. Resonant frequency drift due to temperature variation has a large impact on the narrower passband and a temperature coefficient of frequency (TCF) closer to 0 can broaden the stable temperature range of the resonator. This paper proposes a method of etching grooves in the area of the piezoelectric layer not covered by the Interdigital transducer (IDT) electrodes to improve the temperature stability of the Lamb resonator. Through the finite element method and theoretical analysis, the phase velocity, group velocity, and TCF dispersion curve of different modes of the resonator with groove structure were determined. The reason for the change of TCF under different normalized thicknesses of AlN was explained through the conversion of the LWR from a contour mode resonator (CMR) to a Cross-Sectional Lamé Mode Resonator. Simulation and test have shown that etching grooves have the effect of reducing TCF by adjusting the electromechanical coupling coefficient. The test shows that 205 nm-depth grooves can lower the TCF of the S0 mode IDT-Open LWR from −13.3 to −5.1 ppm/°C and S1 mode from −36.8 to −9.0 ppm/°C, respectively. The TCF of S0 and S1 mode LWRs decreased by 61.7% and 75.5%, respectively, after 205 nm groove etching. The groove etching method greatly raises the temperature stability of the LWR, enabling Lamb wave filters to operate stably over a wider temperature range.

The excellent performance of oxygen evolution reaction on stainless steel electrodes by halogen oxyacid salts etching

Development of low-cost, efficient, and stable electrocatalysts for oxygen evolution reaction (OER) is the key issue for a large-scale hydrogen production. Recently, in-situ corrosion of stainless steel seems to be a feasible technique to obtain an efficient OER electrode, while a wide variety of corrosive agents often lead to significant difference in catalytic performance. Herein, we synthesized Ni-Fe based nanomaterials with OER activity through a facile one-step hydrothermal etching method of stainless steel mesh, and investigated the influence of three halogen oxyacid salts (KClO3, KBrO3, KIO3) on water oxidation performance. It was found that the reduction product of oxyacid salts has the pitting effect on the stainless steel, which plays an important role in regulating the morphology and composition of the nanomaterials. The KBrO3-derived electrode shows optimal OER performance, giving the small overpotential of 228 and 270 mV at 10 and 100 mA cm−2 respectively, a low Tafel slope of 36.2 mV dec−1, as well as durable stability in the long-time electrolysis. This work builds an internal relationship between the corrosive agents and the OER performance of the as-prepared electrodes, providing promising strategies and research foundations for further improving the OER performance and optimizing the structure of stainless steel electrodes.

Solvent-Assisted Structural Modifications of Sulfur Dots Followed by Time-Dependent Emergence of a New Emissive State and Long-Lived Afterglow.

Sulfur dots are a new class of recently developed nonmetallic luminescent nanomaterials with various potential applications. Herein, we synthesized sulfur dots using a mild chemical etching method and then modified the structural features of the as-synthesized sulfur dots using a slow and defined solvent-assisted aggregation process. This increases the particle size and overall crystallinity along with the modifications of the surface functional groups, which eventually show a new emission band at longer wavelengths. Detailed photophysical and temperature-dependent luminescence studies confirmed that the new emissive state evolves due to interparticle interactions in the excited state. Furthermore, the occurrence of a new emissive state in a longer-wavelength region helped reduce the energy gap between the lowest excited singlet state and the lowest excited triplet state in modified sulfur dots, resulting in an aqueous stable room-temperature phosphorescence/afterglow emission through efficient intersystem crossing. This typical efficacious afterglow emission directly shows the potential applicability of structurally modified sulfur dots in encryption devices and can also be potentially effective in light emitting diodes (LED) and sensing devices.

Effect of the insertion of silver nanoparticles on the performance and electrical features of Ag/SiNWs Schottky diode

In this paper, we studied the effect of the passivation of silicon nanowires (SiNWs) by silver nanoparticles (AgNPs) on the efficiency of Ag/SiNWs/Si Schottky diodes. SiNWs are obtained by one-step Ag-assisted chemical etching method. AgNPs were deposited on SiNWs using an electroless dipping method. Schottky junction devices have been successfully made using silicon nanowires coated with silver nanoparticles. The current–voltage (I-V) characteristics of Ag/AgNPs-SiNWs Schottky diode have been investigated by varying the immersion time in silver nitrate solution from 1 to 5 min. The I-V characteristics presented in logarithmic scale confirmed the domination of SCLC conduction mechanism at high voltage. The ideality factor (n), height of potential barrier (φb) and series resistance (Rs) of diodes are calculated by adopting the Cheung method. Compared to the Ag/SiNWs Schottky junction, the diode that presents AgNPs at the interface shows a significant improvement in electrical parameters. The potential barrier reaches 1.09 eV and the ideality factor is reduced to 2.64 with the presence of AgNPs for an immersion time of 1 min. Norde’s equation has also been used to calculate the series resistance and the potential barrier. The results obtained by Norde method are slightly shifted compared to those found by Cheung functions while the findings concerning the optimization of the immersion time are practically the same.

Crystal-Phase-Selective Etching of Heterophase Au Nanostructures.

Selective oxidative etching is one of the most effective ways to prepare hollow nanostructures and nanocrystals with specific exposed facets. The mechanism of selective etching in noble metal nanostructures mainly relies on the different reactivity of metal components and the distinct surface energy of multimetallic nanostructures. Recently, phase engineering of nanomaterials (PEN) offers new opportunities for the preparation of unique heterostructures, including heterophase nanostructures. However, the synthesis of hollow multimetallic nanostructures based on crystal-phase-selective etching has been rarely studied. Here, a crystal-phase-selective etching method is reported to selectively etch the unconventional 4H and 2H phases in the heterophase Au nanostructures. Due to the coating of Pt-based alloy and the crystal-phase-selective etching of 4H-Au in 4H/face-centered cubic (fcc) Au nanowires, the well-defined ladder-like Au@PtAg nanoframes are prepared. In addition, the 2H-Au in the fcc-2H-fcc Au nanorods and 2H/fcc Au nanosheets can also be selectively etched using the same method. As a proof-of-concept application, the ladder-like Au@PtAg nanoframes are used for the electrocatalytic hydrogen evolution reaction (HER) in acidic media, showing excellent performance that is comparable to the commercial Pt/C catalyst.

Free-standing COF nanofiber in ion conductive membrane to improve efficiency of vanadium redox flow battery

The ion sieving effect of the porous two-dimensional covalent organic frameworks (COFs) in vanadium redox flow battery (VRFB) was greatly restricted by the brittleness and easy agglomeration of COFs in ion conductive membranes. Herein, the strategy of free-standing COF nanofiber as continuous ion conductive pathways is proposed to maximize the selective ion conduction of COFs. The free-standing TFP-TAPA electrospun COF nanofiber mat was fabricated by an in-situ growth-template etching method, densified with sulfonated polybenzimidazole (SPBI) and continuously dispersed in the membrane. Fibrillization gives rigid COF materials excellent flexibility to be freely bent, induces the orientated aggregation of sulfonic acid groups via hydrogen bonding for proton hopping, as well as the long-range vanadium ions repelling barrier via the sieving pores (6 Å) and Donnan effect of the imine groups in COF. The TFP-TAPA COF nanofiber continuous membrane shows 3 folds of H+/Vn+ selectivity over Nafion212, achieves excellent VRFB energy efficiency of about 80.5 % at 200 mA cm−2, which surpasses most state-of-the-art COFs based ion conductive membranes for VRFBs.

Enhancing bacterial control and daylight-driven water remediation with chitosan-impregnated MoC nanosheets.

The functionalization of nanoparticles with 2D nanosheets is an effective approach to enhance their functional properties for pollutant removal. This research outlines the synthesis of a 2D-delaminated molybdenum carbide (MXene) chitosan nanocomposite (2D-d-Mo2CTx-Cs NC) with bacterial control and photocatalytic properties for dye adsorption. The nanocomposite includes Tx-surface terminating groups O, OH, and F. In this investigation, the composite was synthesized using the etching method and its formation was confirmed through UV spectra at 288nm. It was characterized through FTIR, XRD, Particle size, Zetapotential, FESEM, HRTEM, EDAX, and XPS analyses. FTIR spectral analysis of NC suggests that amines are formed through a Schiff base reaction between glutaraldehyde and Cs, or through the interaction of terminal aldehydes and carbonyl groups. The XRD analysis confirmed the crystalline structure of the composite. FESEM images revealed irregularly structured nanosheets (NSs) material in the prepared 2D-d-Mo2CTx-Cs NC samples. HRTEM images revealed 2D-d-Mo2CTx NSs impregnated onto Cs with an average size of 50nm, as confirmed by a particle size analyzer, with a zeta potential value of -15mV. Additionally, Mo, C, N, and O are the most significant elements present in the NC, as confirmed by EDAX and XPS analyses. Further, biocompatibility testing of 2D-d-Mo2CTx-Cs NC yielded positive results. Moreover, under sunlight, the composites effectively adsorbed methylene blue with a 90% adsorption capacity, as confirmed by kinetic studies. Furthermore, the synergistic effect of Cs and d-Mo2CTx NSs resulted in significant antibacterial (50-200µl of 1mg/ml) and antibiofilm activity (100µl of 1mg/ml) against pathogenic bacteria. Furthermore, this study represents the first report on the use of 2D-d-Mo2CTx-Cs NC for daylight-influenced photocatalytic applications with a bacteria-controlling effect.

Hf-Doped CoP Hollow Nanocubes as High-Performance Electrocatalyst for Oxygen Evolution Reaction.

Designing and synthesizing hollow frame structures with unique three-dimensional open structures in electrocatalysis remain a challenge. Etching is an effective method to synthesize metal-organic frameworks (MOFs) with a hollow structure and rich function. Herein, we report the design and synthesis of Hf-doped CoP hollow nanocubes by selective etching and ion exchange. Different from the traditional etching method, we used acid xylenol orange solution to etch typically the (211) crystal face of ZIF-67, obtaining the unique bell-like structure, named XO-ZIF-67. Subsequently, Hf-doped CoP hollow nanocubes were formed by Hf4+ doping and simple phosphating treatment. Electrochemical tests showed that the overpotential of the obtained catalyst is only 291 mV at the current density of 10 mA cm-2 when applied in catalyzing the oxygen evolution reaction (OER). Furthermore, the catalyst shows excellent stability when running in 1 M KOH solution for 25 h.

Eco‐friendly glass wet etching for MEMS application: A review

AbstractGlass is one of the most essential materials in various industrial fields. A representative application is as interposers in the semiconductor and display industries and microfluidic devices in the bio‐industry. Due to technological advancements, electric devices and various products are becoming lighter and smaller. Consequently, precision processing of the substrate is becoming increasingly important. One significant leading technology among these is through glass via (TGV) technology, which is attracting attention as a future alternative to through silicon via. In particular, TGV should be capable of microfabrication with a large aspect ratio and a consistent small hole size. TGV is typically fabricated using a wet etching process, so wet etching technology is a prominent focus in microfabrication. However, glass has isotropic properties, making achieving a high aspect ratio difficult. Traditionally, research on the wet etching method using hydrofluoric acid (HF) has been conducted. Nevertheless, HF etching has several disadvantages, including air pollution and human harm. Additional studies have been performed to address these issues. This review paper will cover the conventional HF‐based wet etching method and alternative HF etching processes (eco‐friendly materials). This technology would significantly help overcome the traditional problems associated with HF etching and fabricating precision‐processed glass in the semiconductor, display, and bio‐device industries.

Effects of different pretreatments on Ti/RuO2-TiO2 anode

In this study, H2C2O4, H2SO4, HNO3, and HCl were used to etch the TA2 titanium matrix at the same concentration and temperature, and the effects of different acid etching methods on the properties of the titanium matrix and Ru-Ti electrode were investigated. The surface morphology of the titanium substrate and anode after acid etching was observed by scanning electron microscopy (SEM), while the electrochemical performance of the anode was determined by cyclic voltammetry (CV), linear sweep voltammetry (LSV), and tafel plots. SEM observations showed that H2C2O4 had the best etching effect on the titanium substrate, as the scratches were uniform, and the surface cracks of the prepared anode reached 4–6 μm; Analysis of the CV curves revealed that the Ti/RuO2-TiO2 anode prepared by H2C2O4 etching had the highest surface charge capacity (172 mC) compared to the anodes prepared by other acid etchings, while the LSV curves showed that the Ti/RuO2-TiO2 anode after H2C2O4 etching had the lowest polarization potential (1.232 V). Tafel curve analysis revealed that the corrosion potential of the Ti anode prepared by H2C2O4 etching was 0.203 V, and the self-corrosion current density was −5.11 A cm−2, indicating that the corrosion resistance of the Ti anode prepared by H2C2O4 treatment is the weakest. X-ray photoelectron spectroscopy analysis showed that the electrode surface changed from Ru4+ to Ru3+ after corrosion, with the Ti2p spectra showing similar transition from Ti4+ to Ti3+.

Potential applications for modified Klemmsolutions

Abstract The article describes various modifications of Klemm etching solutions and their applications to different materials. In addition to classic immersion etching, electrolytic etching is also used for the first time, demonstrating the potential of this etching method based on sodium thiosulfate and potassium metabisulfide for other materials.

GaInN‐Based Blue LED with a PEDOT/PSS Hole Transport Layer

In this study, a nitride‐based blue PEDOT‐LED is fabricated and a preliminary assessment of the device characteristics is done. To prevent detaching of the PEDOT/PSS layer from the LED substrate when immersing in water or developing solution, Ag was deposited on top of the PEDOT/PSS layer. Additionally, exfoliation is suppressed by reducing the developing time and protecting the wafer edge with a photoresist. Different etching methods for Ag and PEDOT/PSS are investigated. The Ar ion‐beam etching resulted in uniform and flat‐etched surfaces. Regarding the performance of the PEDOT‐LEDs, a high Mg‐doping concentration of 1.0 × 1020 cm−2 leads to a relatively low threshold current voltage in the V–I characteristics. However, for the PEDOT‐LED with p‐Al0.25Ga0.75 N EBL, a steep light output saturation is observed at high current density when analyzing the L–I characteristics.

Enhancing long-term stability in oxygen evolution through in-situ etching of phase segregation Fe-Mn oxide

Phase segregation, induced by the dynamic evolution of the electrode surface during operation, impacts the stability of catalysts involved in the energy conversion process, specifically in the oxygen evolution reaction (OER). To address this issue, we propose an innovative electrochemical etching method for the in-situ elimination of the surface phase segregation in FeMn layered double oxides (FeMn LDO). The Mn-rich structure on the FeMn LDO surface, which undergoes a transition process from Mn3O4 to MnO4−, can be eliminated during the etching process, thereby restoring the OER performance of the catalyst. The resultant electrode shows a low overpotential of 245 mV at 10 mA cm−2 and robust durability of 1250 h at 100 mA cm−2, marking one of the highest stabilities among transition-metal based OER catalysts. Our insights into the electrode surface evolution provide valuable guidance for designing stable electrode materials.

Boosting sodium storage performance of biomass-derived porous carbon anodes by surface functionalized strategy

In order to enhance the sodium ion storage performance of biomass-derived carbon anode materials, a surface functionalization strategy was employed through a simple acid etching method on porous carbon. The resulting functionalized carbon exhibits a hierarchically porous structure, expanded interlayer spacing, and oxygen-containing functional groups. The redox reactions occurring at the surface between Na ions and carbonyl groups provide additional sites for sodium ion storage, thereby improving cycling capacity and rate capability. Theoretical calculations and electrochemical tests further demonstrate that the functionalized carbon can increase the surface-controlled sodium storage capacity by modifying the transport and adsorption processes of sodium ions. After 200 cycles at a current density of 100 mA g−1, the carbon anode, which was surface-functionalized with an etching time of 6 h, achieve a high reversible capacity of 273 mA h g−1. Furthermore, it displays improved rate performance with a capacity of 194 mA h g−1 at a high current density of 2 A g−1 for sodium-ion batteries. This study introduces an effective and general strategy for the cost-effective and large-scale synthesis of carbon anode materials for sodium-ion batteries.