KOH Environment Research Articles

A Multi‐Site Synergistic Effect in High‐Entropy Alloy for Efficient Hydrogen Evolution

AbstractUnraveling the mechanism driven by electronegativity‐dominated electronic configuration is crucial for developing high‐entropy alloys as efficient catalyst for hydrogen evolution reaction (HER). In this work, different atoms with diverse electronegativities are explored to regulate the electrocatalytic activity of PtFeCoNi@HCS toward HER, resulting in PtFeCoNiCuCr@HCS with an overpotential of 29 mV at 10 mA cm−2 and enhanced durability surpassing that of commercial 20% Pt/C in KOH environment. Based on various physicochemical and electrochemical techniques as well as density functional theory calculations, a multi‐site synergistic effect within PtFeCoNiCuCr@HCS material is elucidated in terms of both structural composition and electrocatalytic process. Briefly, Pt and Cu serve as the fundamental elements to form face‐centered cubic crystal framework, Cr primarily functions as an electron donor to regulate the electronic configuration, Co serves as the main active site for water dissociation, and the produced hydrogen species prefer to transfer toward Pt, Fe, and Cu sites for hydrogen formation. This work offers an in‐depth insight on the synergistic mechanism in high entropy alloys and is helpful for designing efficient electrocatalysts.

Synthesis of NiO/ZnO/GO nanocomposites derived from Ni-Zn-H2BDC metal−organic framework for high-performance supercapacitor electrodes

The NiO/ZnO/graphene oxide (GO) nanocomposite was created for use in supercapacitor electrode materials. The GO component was synthesized using a modified version of the Hummers' method, NiO/ZnO nanomaterials have been successfully synthesized through the derivation of a Ni-Zn-H2BDC based metal-organic framework (Ni-Zn-MOF) and the nanocomposite of NiO/ZnO/GO was synthesized using the co-precipitation method. Material characterization techniques, including XRD, FTIR, FE-SEM, and EDX, were employed to assess the structure and purity of the synthesized material, confirming its successful synthesis. Electrochemical tests were conducted to evaluate the effectiveness of the synthesized materials as supercapacitor electrodes. These tests encompassed cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) in an alkaline electrolyte (3 M KOH). The electrochemical tests were performed on Ni-Zn-H2BDC, NiO/ZnO, GO, and NiO/ZnO/GO nanocomposite electrodes in a 3 M KOH environment. Notably, the NiO/ZnO/GO nanocomposite electrode exhibited the highest specific capacity at a current density of 0.5 A/g, reaching 1800 F/g. These results demonstrate the superior charge-discharge capabilities and capacity of the synthesized NiO/ZnO/GO nanocomposite, confirming the success of the study.

Viologen-Cucurbit[7]uril Based Polyrotaxanated Covalent Organic Networks: A Metal Free Electrocatalyst for Oxygen Evolution Reaction.

Viologen-based covalent organic networks represent a burgeoning class of materials distinguished by their captivating properties. Here, supramolecular chemistry is harnessed to fabricate polyrotaxanated ionic covalent organic polymers (iCOP) through a Schiff-base condensation reaction under solvothermal conditions. The reaction between 1,1'-bis(4-aminophenyl)-[4,4'-bipyridine]-1,1'-diium dichloride (DPV-NH2) and 1,3,5-triformylphloroglucinol (TPG) in various solvents yields an iCOP-1 and iCOP-2. Likewise, employing cucurbit[7]uril (CB[7]) in the reaction yielded polyrotaxanated iCOPs, denoted as iCOP-CB[7]-1 and iCOP-CB[7]-2. All four iCOPs exhibit exceptional stability under the acidic and basic conditions. iCOP-CB[7]-2 displays outstanding electrocatalytic Oxygen Evolution Reaction (OER) performance, demanding an overpotential of 296 and 332mV at 10 and 20mA cm-2, respectively. Moreover, the CB[7] integrated iCOP-2 exhibits a long-term stable nature for 30h in 1m KOH environment. Further, intrinsic activity studies like TOF show a 4.2-fold increase in generation of oxygen (O2) molecules than the bare iCOP-2. Also, it is found that iCOP-CB[7]-2 exhibits a high specific (19.48mA cm-2) and mass activity (76.74mAmg-1) at 1.59V versus RHE. Operando-EIS study evident that iCOP-CB[7]-2 commences OER at a relatively low applied potential of 1.5V versus RHE. These findings pave the way for a novel approach to synthesizing various mechanically interlocked molecules through straightforward solvothermal conditions.

Synthesis and performance of poly(aryl ether nitrile) anion exchange membranes containing highly dense quaternary ammonium cationic side chains for water electrolysis

Anion exchange membranes (AEMs) are the core components of water electrolysis and suffer from the critical obstacles such as low ionic conductivity and poor alkali resistance stability in practical applications. In this work, a series of AEMs based on poly(arylene ether nitrile)s with high-density quaternary ammonium cationic side chains (PAEN-DQA-x) are synthesized to optimize the conductivity and alkali resistance stability. Their surface morphology and microstructure are characterized by scanning electron microscopy and atomic force microscopy, respectively. The obtained AEMs exhibit good conductivity and the values are in the range of 76.13–119.72 mS/cm at 80 °C. The conductivity retention for the representative PAEN-DQA-0.35 membrane is up to 73% after immersion in 2 M NaOH at 80 °C for 480 h. The current density of the water electrolyzer by PAEN-DQA-0.35 reaches 521.3 mA/cm2 at 2.0 V, and it also remains good stable at a current density of 500 mA/cm2 in a 0.1 M KOH environment.

A NiMOF integrated with conductive materials for efficient bifunctional electrocatalysis of urea oxidation and oxygen evolution reactions.

The development of urea oxidation reaction (UOR) and oxygen evolution reaction (OER) bifunctional electrocatalysts has dual significance in promoting hydrogen energy production and urea-rich wastewater treatment. Herein, a carboxylated multi-walled carbon nanotube (MWCNT-COOH)-ferrocene carboxylic acid (Fc-COOH) modulated NiMOF hybrid material (MWCNT-NiMOF(Fc)) has been synthesized for dual electrocatalysis of the UOR and OER. The material characterization results indicated that MWCNT-COOH and Fc-COOH were integrated into the framework structure of the NiMOF. The direct interaction between the NiMOF and MWCNT/Fc facilitated electron transfer in the hybrid material and led to lattice strain, which improved the charge transfer kinetics, promoted the exposure of more unsaturated Ni sites, and increased the electrochemically active surface area. These factors together enhanced the electrocatalytic activity of MWCNT-NiMOF(Fc) towards the UOR and OER. Using a glassy carbon electrode as the substrate, MWCNT-NiMOF(Fc) exhibited low potential requirements, low Tafel slopes, and high stability. In overall urea and water splitting electrolysis cells, the excellent UOR and OER dual functional catalytic ability and enormous practical application potential of the MWCNT-NiMOF(Fc) modified foam nickel electrode were further demonstrated. On the basis of the above research, the influence of a KOH environment on urea electrolysis was further studied, and the urea electrolysis products were analyzed, promoting a more comprehensive understanding of the catalytic performance of MWCNT-NiMOF(Fc) for urea oxidation. This study provides a new approach for developing high-performance NiMOF-based electrocatalysts for challenging bifunctional UOR/OER applications, and has potential application value in hydrogen production from urea-containing wastewater electrolysis.

Enhanced electrochemical performance of CuO/NiO/rGO for oxygen evolution reaction

To design the highly active, stable electrocatalyst for oxygen evolution is emerging as challenging task for sustainable energy production. Herein, we fabricated the non-noble CuO/NiO/rGO nanocomposite approached by facile chemical co-precipitation method. The successful formation of binary metal oxide nanocomposite with reduced graphene oxide was confirmed with monoclinic CuO and cubic NiO, which is clearly revealed in the XRD diffraction results. By incorporating the CuO and NiO into the rGO sheets results homogeneous tiny nanoparticles morphology decorated on the graphene sheets which improving interaction among metal nanoparticles and carbon based products. The electrocatalytic performance of resultant binary metal oxide nanocomposite with rGO was investigated in alkaline KOH environment towards oxygen evolution reaction. The 200 mV overpotential was attained at 10 mA/cm2 with smaller 165 mV/dec Tafel value. The elevated electrochemical surface area (ECSA) value of 132.5 cm2 was estimated from cyclic voltammetry analysis of optimized CuO/NiO/rGO electrocatalyst. The electrochemical impedance spectrum of the prepared electrocatalyst shows that the low 0.04 Ω charge transfer resistance is highly desirable to the better conductivity. The prepared CuO/NiO/rGO electrocatalyst stability was verified by chronoamperometry test at low 10 mA/cm2 and exhibited stable performance up to 16 h towards OER. Hence, this work contributes innovative synergistic approach for growth of cost effective binary metal-oxide (CuO/NiO) nanocomposite combined with conductive carbon material for oxygen evolution reaction.

Fabricating Ru Atom-Doped Novel FeP4/Fe2PO5 Heterogeneous Interface for Overall Water Splitting in Alkaline Environment.

Developing bifunctional electrocatalysts with low-content noble metals and high activity and stability is crucial for water splitting. Herein, we reported a novel Ru doped FeP4/Fe2PO5 heterogeneous interface catalyst (Ru@FeP4/Fe2PO5) for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) by heat treatment coupling electrodeposition strategy. Experiments disclosed that Ru@FeP4/Fe2PO5 proclaimed excellent catalytic activity for the OER (249 mV@100 mA cm-2) and HER (49 mV@10 mA cm-2) in a 1 M KOH environment. More importantly, the mass activity and turnover frequency of Ru@FeP4/Fe2PO5 were 117 and 108 times higher than that of commercial RuO2 at an overpotential of 300 mV during the OER, respectively. In addition, the assembled Ru@FeP4/Fe2PO5 || Ru@FeP4/Fe2PO5 system could retain superior durability in a two-electrode system for 134 h at 300 mA cm-2. Further mechanism studies revealed that Ru atoms in Ru@FeP4/Fe2PO5 act in a key role for the excellent activity during water splitting because the electronic structure of Ru sites could be optimized by the interaction between Ru and Fe atoms at the interface to strengthen the adsorption of reaction intermediates. Besides, the introduction of Ru atoms could also enhance the charge transfer, which effectually accelerates the reaction kinetics. The strategy of anchoring Ru atom on novel heterostructure provides a promising path to boost the overall activity of electrocatalysts for water splitting.

Self‐supported bimetallic based materials deeply self‐reconstructing electrocatalysts for advances in hydrogen production

AbstractTo overcome the energy demand, environmental pollution, and global warming, replacing fossil fuels using clean and renewable hydrogen energy is a promising strategy. Water catalysis is the key step toward industrial hydrogen generation. Herein, we obtained remarkable performance of CuCo for hydrogen evolution reaction (HER) in sulfuric acid and potassium hydroxide. The CuCo nanocomposite functional material on nickel foam is rich in copper nanoparticles. The CoCu oxide on nickel foam showed catalytic performance superfast in the HER in a 1 M KOH environment at 1.62 V to carry a 10 mA/cm2 current density and no decrease in current afterward a non‐stop run for 25 hr. CoCu (S2) has a Tafel slope of (a) 69 mV/dec in a 0.5 M H2SO4 and (b) 119 mV/dec in a 1 M KOH. It has been found to be cost‐effective, highly active, and healthy for energy conversion by electrochemical. Moreover, the capabilities of charge storage were also inspected. It strongly provides a capacitance of 681 and 607 F/g at a 1 A/g admirable rate of capacitance retention. The attractive features of CoCu oxide are present in more abundance and superior for the HER kinetics activity. The electrocatalyst provides better stability and durability and provides long‐term applications for the advance of a functional catalyst for charge storage, and water splitting applications is strongly demonstrated.

Tannery waste as a renewable source of nitrogen for production of multicomponent fertilizers with biostimulating properties.

The studies presented in this work show that solid tannery waste-like shavings can be used as high-protein materials for fertilizer production following the concept of the circular economy. To select appropriate process parameters (mass ratio of shavings meal to the hydrolyzing agent (S:L), hydrolysis medium concentration, temperature) and to ensure the highest possible hydrolysis efficiency, it is useful to apply the well-known response surface methodology (RSM). The analyses revealed that chromium shavings (SCr) were most preferably treated with 10% KOH in a ratio of S:L 1:1 with the process being carried out at 160°C (6.59% N). The optimal hydrolysis conditions for non-chromium (S) shavings were: S:L ratio 1:2, 10% H2SO4, and temperature 160°C (4.08% N). Chromium concentrations in hydrolysates from S and SCr shavings obtained under optimal conditions were 15.2mg/kg and 9483mg/kg, respectively. Hydrolysate samples were analyzed by reversed-phase high-pressure liquid chromatography (RP-HPLC) that revealed that the type of hydrolysis (acidic/alkaline) affects the amino acid profile. Approximately 4.5 times more amino acids were extracted in the KOH environment than during acidic treatment. The hydrolysates contained mainly glycine, alanine, and proline, which are primarily responsible for stimulating plant growth by supporting chlorophyll synthesis, chelating micronutrients, improving pollen fertility, or resistance to low temperatures. The conversion of tannery waste into fertilizer requires the control of contaminant levels, especially chromium, which can oxidize to the carcinogenic form Cr(VI) that is hazardous to humans and the environment.

Nanoporous Amorphous Fe78Si9B13 Alloys for Hydrogen Evolution in Alkaline Media

A serious of corrosion treatments are applied upon a melt-spun amorphous Fe78Si9B13 alloy to fabricate nanoporous structure for improving the alkaline hydrogen evolution reaction (HER) performances. The corrosion treatment produces a large number of nanopores on the surface, leading to remarkably improved HER performances. By corroding in 2M NaOH solution for 120 min, abundant pores with a diameter of about 50~100 nm were uniformly formed on the surface of the amorphous alloy. The nanoporous amorphous alloy can obtain a current density of 10 mA cm−2 at the overpotential of only 199 mV in 1M KOH environment, which is significantly reduced from that of the original melt-spun alloy of 386 mV under the same conditions. The corroded sample also shows excellent cycling performances. Microstructural study shows that after 1000 CV cycles the nanoscale columnar structure formed on the surface of the corroded sample are denser and larger than that of the melt-spun alloy, which effectively inhibit the increase range of the polarization resistance of the alloy.

Sustainable NO removal and its sensitive monitoring at room temperature by electrogenerated Ni (I) electron mediator

Online monitoring of gas pollutants in the gas phase at room temperature using an electrochemical macro gas flow sensor is challenging and important for the pollutant treatment process. In this work, for the first time, we tried to explore the homogeneous and heterogeneous application of Ni(II) (CN)42− in the KOH environment for the removal and monitoring of toxic nitric oxide gas. The homogeneous electrogenerated Ni(I) (CN)43− was effectively removing the toxic nitric oxide gas by electro scrubbing method and the novel Ni(II) (CN)42− and KOH modified electrode used for heterogeneous sensor application with high sensitivity, and reliability toward Nitric oxide gas. The sensor showed enhanced gas diffusion and high sensitivity. Scanning electron microscopy and X-ray diffraction confirmed the modification of the carbon felt electrode. In a high concentrated KOH environment, the active mediator stabilized the sensor for a long time compared to the neutral environment. The Ni(II) (CN)42− fabricated carbon felt was used to monitor the concentration of nitric oxide gas pollutant; the calculated sensitivity was approximately −0.33 mA ppm−1 cm−2. The current increased linearly with increasing nitric oxide concentration up to 12 ppm and was validated by online gas chromatography. The developed electrochemical gas flow sensor successfully monitored the unremoved nitric oxide gas at the exit from the MER electro-scrubbing process; the concentration was calculated using a calibration plot.

Evolution of chemo-mechanical effects during single grit diamond scratching of monocrystalline silicon in the presence of potassium hydroxide

Efficiency and workability of silicon wafers for various applications depend on theirs surface integrity and damage free structures. Productivity of mechanical processing on silicon wafers is always limited by occurrence of cracks and brittle mode material removal at high depth of cut. This study presents a method of using controlled concentration of KOH solution during diamond micro-scratching of silicon and investigates the chemo-mechanical effects of KOH solution with respect to cutting speed. To establish the chemo-mechanical theory of cutting, responses of physical and material properties of silicon in presence of KOH solution are captured and correlated with mechanical responses during micro-scratching. Zeta potential and nanohardness are greatly reduced in KOH environment. Ductile mode is found to be extended by using 10 wt% KOH. Crack/chipping length is observed to be first increasing with increase in cutting speed at low range (0.6–20 mm/min) and then decreasing on further increase in the cutting speed (20–200 mm/min). Stability in cutting force signature and behavior of material flow along the scratch length is also found to be improved by using KOH. Adhesive wear and abrasive wear are found to be the main forms of single grit wear, which is significantly reduced in the presence of KOH. The experimental results on different mechanical and physical phenomena in this study are of great importance for establishing the theoretical insight into material removal behavior and selection of machining parameters during micro-machining of silicon wafer.

Strontium phosphide-polyaniline composites for high performance supercapattery devices

Supercapattery, a hybrid energy storage device, gained remarkable attention due to its extraordinary energy storage performance. These devices constitute much better power and energy densities than supercapacitors and batteries. Here, we have investigated strontium phosphide and polyaniline (PANI) composites for supercapattery devices. The strontium phosphide was synthesized via facile sono-chemical method whereas the polyaniline was obtained through polymerization of aniline in acidic environment. Electrochemical performance of different mass ratios of strontium phosphide and polyaniline that are 75/25% and 50/50% were tested in three electrode assembly. Electrochemical characterization including galvanostatic charge discharge (GCD), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) were performed to probe the electroactive nature of the composites. The initial characterization predicts the battery grade nature of synthesized composites which were confirmed through theoretical approach. The sample S3 indicates highest specific capacity of 192 Cg-1 in CV at a scan rate of 10 mV/s and 196 C/g in GCD at a current density of 0.4 A/g. In light of electrochemical performance, the 50/50% composite electrode was further investigated for supercapattery by sandwiching it with activated carbon electrode (capacitive electrode). The supercapattery (AC//S3) operates reliably at 0–1.7 V wider potential window in 1 M KOH environment and showing excellent specific capacity of 122.5 C/g at 0.6 A/g while demonstrating better rate capability of 37% at 3.0 A/g. Besides, this device expresses an outstanding performance in terms of energy and power density, 28.9 Wh/kg of maximum specific energy is achieved in line with 1020 W/kg of power density at 0.4 A/g. This device reveals an excellent power density of 5100 W/kg at the cost of 10.95 Wh/kg energy density. In last the device durability was examined by subjecting it to 2000 consecutive charge discharge cycles. Strontium phosphide/PANI composites would be novel electrode materials for state of the art supercapattery devices.

Multi-wall carbon nanotube-supported palladium–cobalt oxide nanoparticle as efficient catalyst for oxygen reduction reaction

A facile one-step solvothermal approach is adopted to synthesize a multi-wall carbon nanotube-supported palladium–cobalt oxide nanoparticle catalyst (Pd-CoO/MWCNT) as a highly efficient electrocatalyst for oxygen reduction reaction (ORR) in alkaline conditions. In the composite material, Pd-CoO nanoparticles with an average particle size of 6.2 nm are found uniformly anchored on the MWCNTs. MWCNTs form a conductive carbon network with high specific surface area, which favors both mass transport and charge transfer for the electrochemical reaction. The Pd-CoO/MWCNTs exhibit a comparable ORR activity and excellent durability in 0.1 mol/L KOH environment. More significantly, under electrochemical accelerated durability test, the Pd-CoO/MWCNTs can endure at least 14,000 cycles with negligible activity decay. The improved ORR activity and stability of Pd-CoO/MWCNTs demonstrate the effectiveness of introducing transition metal oxide in the development of high-performance non-Pt catalysts for fuel cells and metal–air batteries.

Mechanism of material removal during nanofinishing of aluminium in aqueous KOH: A reactive molecular dynamics simulation study

In this work, the atomic mechanism of tribo-chemical wear of aluminium at the interface of SiAl in aqueous KOH environment was investigated using a reactive molecular dynamics simulation (R-MDS) for achieving nano-finished surface using the principle of chemically assisted mechanical finishing (CMAF) through chemo mechanical magnetorheological finishing (CMMRF) process. Three attributes of material removal mechanisms were detected in the finishing process. The first is caused by the destruction of parent bonds on the aluminium substrate surface and is assisted by the oxidation. The second is caused by the mechanical stress assisted chemical reaction to bridge new bonds between abrasive and workpiece. The third is caused by rupture of AlAl bonds, as the newly formed bonds are relatively strong. This work shows that the removal of Al atoms from the substrate is a result of both chemical reaction and mechanical effects, and contributes to the understanding of tribo-chemical wear behaviour of CMMRF process. The finished surface shows free of any other contamination which is suitable to employ such surfaces for the micro-electronics fabrication. Experimental results also support the mechanism of CAMF for generating the surface finish of the order of few nanometers.

Dissolution kinetics of molybdite in KOH media at different temperatures

Abstract The dissolution kinetics of synthetic molybdite (MoO3) in a potassium hydroxide (KOH) medium was studied by varying the system temperature, KOH concentration, and particle size. Additionally, the effects of the stirring rate and different reagents such as barium hydroxide (Ba(OH)2), calcium hydroxide (Ca(OH)2), and sodium hydroxide (NaOH) were also evaluated. The experiments were performed in a reactor with controlled temperature and agitation. The results indicated that the dissolution reaction mechanism of molybdite generates potassium molybdate (K2MoO4) without intermediate compounds. Temperature (6–80 °C), KOH concentration (0.0005–0.025 mol/L), and particle size (5–40 μm) positively affected the dissolution of molybdite. The maximum Mo recovery was 67.5% in 0.25 h for 80 °C and 0.01 mol/L KOH. At the lowest temperature (6 °C), which is near the freezing point of water (0 °C), a substantial amount of Mo was recovered (17.8% in 45 min). The kinetics equation describing the molybdite dissolution in a KOH environment indicated that diffusion occurs through the porous layer. The activation energy was calculated to be 47.81 kJ/mol. A reaction order of 1.0 with respect to KOH concentration was obtained and was found to be inversely proportional to the squared particle size. The kinetics equation was obtained. The dissolution of molybdite resulting from the oxidation of a molybdenite concentrate (MoS2) led to a low molybdenum recovery, which was primarily caused by the consumption of KOH by impurities such as CaCO3 and Cr(MO4)3.

Alkali-doped polyvinyl alcohol – Polybenzimidazole membranes for alkaline water electrolysis

We developed an innovative polymer blend system composed of polyvinyl alcohol (PVA) and polybenzimidazole as an anionic membrane for application to zero gap alkaline electrolysers. The challenge was to combine PVA with either poly[2-2′-(m-phenylene)-5-5′-bibenzimidazole] (PBI) or poly (2,5-benzimidazole) (ABPBI) to complement these neutral polymers, which must be doped to conduct, with hydroxyl groups that benefit the OH− transport mechanism. We studied PVA-PBI and PVA-ABPBI membranes with compositions varying between 2:1 and 8:1, with 4:1 being best ratio. PVA is crosslinked inside PVA-PBI 4:1 and PVA-ABPBI 4:1 membranes with glutaraldehyde (GA) by immersion in a reaction solution with different GA contents ranging from 0.5vol% to 50vol% to enhance the stability of the membranes. The chemical stability in a KOH environment, thermal and mechanical properties, surface morphology, swelling, water/KOH sorption, and conductivity of the linear alkali-doped (L-PVA-PBI, L-PVA-ABPBI) and crosslinked (C-PVA-PBI, C-PVA-ABPBI) membranes were analysed. The best results were observed for the C-PVA-ABPBI 4:1 membrane crosslinked in 0.5vol% GA, which exhibited specific conductivities at 90°C of 50mScm−1 and 90mScm−1 when doped using 15wt% and 30wt% KOH, respectively. In short-term electrolysis tests performed with circulated 15wt% KOH at 50°C, this membrane exhibited a current density that was twice that of the commercial porous Zirfon® diaphragm (i.e., 300mAcm−2 and 140mAcm−2, respectively) at a cell voltage of 2.0V. The performance achieved with the C-PVA-ABPBI membrane in a 15wt% KOH electrolyte at 70°C was good (i.e., 360mAcm−2 at a cell voltage of 1.9V).

Polymer anion-selective membrane for electrolytic water splitting: The impact of a liquid electrolyte composition on the process parameters and long-term stability

In the present study the impact of KOH replacement by a NaHCO3 or Na2CO3 solution on the performance of alkaline water electrolysis and the life-time of an anion-selective polymer electrolyte was assessed. In the first instance, the impact of the electrolyte composition on the kinetics of the electrode reactions was studied. Subsequently the ionic conductivity of the membrane, in the form of individual anions, and the efficiency of the alkaline water electrolysis process were evaluated by means of electrochemical impedance spectroscopy and a laboratory single-cell alkaline water electrolyzer. The anion used was observed to make a significant impact both on the ionic conductivity as well as on the kinetics of the anode reaction, resulting in reduced electrolysis efficiency. A stability test revealed kinetics of chemical degradation of the polymer anion-selective membrane in a Na2CO3 solution similar to those in a KOH environment at 70 °C. An alternative approach of decreasing the temperature to 50 °C prolonged the chemical stability and made less impact on the process efficiency.

Nanoscale Defect Generation in CMP of Low-k/Copper Interconnect Patterns

Chemical mechanical polishing (CMP) can lead to nanoscale damage in films and surface features due to normal and lateral deformations of the surface. Defects arise due to the synergistic effects of chemical and mechanical mechanisms. This occurrence increases with severity as feature sizes are on the same order as abrasive polishing particles and materials decrease in stiffness, as with advanced low- dielectrics. Here, relationships describing the response of normal and lateral surface deformations have been developed experimentally and from contact modeling. This is achieved by atomic force microscopy nanoscratching with diamond tips in a KOH environment to simulate CMP processing conditions. The deformations are related to the applied normal load, friction coefficient, film properties, and line densities. The deformations are observed to have critical loads of 1 and associated with normal and lateral deformations, respectively, which are on the same order as actual CMP particle pressure estimates.

Stabilization of porous silicon surface by thermal decomposition of acetylene

A feasible route to produce hydrocarbon termination to the porous silicon (PSi) surface has been introduced using thermal decomposition of acetylene molecules. Treatment temperatures lower than 600 °C enable the use of continuous acetylene flushing during the treatment without problems arising from the graphitization of acetylene. The continuous acetylene flushing was found to significantly improve the quality and efficiency of the treatment. The decomposition process starts at low temperatures and appears to consist of three different parts as a function of temperature. It was also found that the treatment time has some effects on the treatment efficiency. The hydrocarbon terminated PSi surface was found to be hydrophobic, when the treatment temperature was below 680 °C. Due to the hydrogen desorption, the surface quickly changes to hydrophilic above 700 °C. Thermal oxidation studies of the treated surfaces show improvements in the stability against oxidation and the hydrocarbon termination was found to be very stable even in aqueous KOH environment.