Solution Interface Research Articles

Electrokinetic Effect of a Two-Liquid Interface within a Slit Microchannel.

This paper presents an investigation of the electrokinetic effect at a two-liquid (immiscible liquid-aqueous solution) interface within a slit microchannel using a three-dimensional (3D) numerical model, with a particular focus on the impact of the surface ζ-potential and liquid phase height on the interface electrokinetic velocity. The findings indicate that the direction of the interface movement depends on the ζ-potentials at the two-liquid interface and the microchannel wall. When the absolute value of the negative ζ-potential at the interface is smaller than that at the wall, the interface moves toward the negative pole of the applied direct current (DC) electric field; conversely, it moves in the opposite direction. The velocity of interface motion decreases as the height of the aqueous phase and the dynamic viscosity ratio between the immiscible liquid and the aqueous solution increase. Conversely, the velocity increases with an elevation in the height of the immiscible liquid phase and the DC electric field intensity. This study holds significant importance in elucidating the patterns of change in fluid interface electrokinetic effects and their potential applications in manipulating and separating particulate pollutants within water systems.

Silver, copper, and cobalt trimetallic nanoparticles; synthesis, characterization and its application as adsorbent for acid blue 7 dye

Abstract The synergistic effects of metal complex nanoparticles in remediation of environment had opened a versatile field of research as providing differential attractive forces for a given pollutant on their surfaces. Herein, trimetallic nanoparticles of silver, copper and cobalt (Ag–Cu–Co TNPs) were prepared via chemical reduction method using sodium borohydride as reductant which were then characterized through SEM, EDX, XRD and FT-IR analytical techniques. As model dye, acid blue 7 was adsorbed on the surface of fabricated particles utilizing batch adsorption approach. The adsorption conditions like temperature, adsorbent dosage, pH, and contact time were optimized to get maximum adsorption of the selected dye which were; 333 K, 0.01 g, pH 6 and 30 min respectively. The adsorption data were analyzed using kinetic and isotherm models, with the linear pseudo 2nd order kinetics and Langmuir models being the most suitable. The maximum adsorption capacity at 333 K was found to be 74.07 mg/g. Thermodynamic variables such as entropy (ΔS°), enthalpy (ΔH°), and Gibbs free energy (ΔG°) changes were calculated to understand the adsorption feasibilities. Results indicated that the adsorption process was endothermic (ΔH° = 6.867 KJ mol−1) and spontaneous ΔG° (J mol−1) −219.2, −702.9 and −1086.6 at 293 K, 313 K and 333 K respectively. The entropy change (ΔS° = 24.185 J mol−1 K−1) suggested an increased disorder at the solid–solution interface during adsorption.

Fabrication of Oriented MOF-Based Mixed Matrix Membrane via Ion-Induced Synchronous Synthesis.

Developing a facile strategy for constructing oriented mixed matrix membranes (MMMs) with uniformly dispersed and high-loading metal-organic frameworks (MOFs) is a crucial scientific challenge in probing the enhanced capability and potential applications of MOF-polymer MMMs. Herein, a novel synchronous synthetic method for constructing oriented CuBDC/poly(m-phenylenediamine) (CuBDC/PmPD) MMM with uniform MOF dispersion at high loading at the air-solution interface via the dual function of metal ions is reported. The resulting MMM exhibits excellent separation performance in ion sieving and seawater desalination due to the structural integrity of the proposed membrane and the highly interconnected channels created through the oriented distribution of MOF in a polymer matrix. Such a cutting-edge approach may provide promising insights into the development of advanced MMMs with optimized structure and superior performances.

High temperature Raman spectroscopic analysis of the crystal growth of Bi2ZnOB2O6

Micromechanism of crystal growth has received considerable attention as a fundamental subject. However, in situ observation of the crystal growth process remains challenging. In this study, high-temperature Raman spectroscopy has been utilized to investigate the growth pattern of Bi2ZnOB2O6 crystals via in situ exploration of the starting solution structure near the crystal–solution interface. The experimental results show that the solution primarily consists of ZO4 and BO3 units corresponding to 370, 539, 664, and 1293 cm−1 vibration frequencies. These units connect with each other forming longer chains in the area close to the crystal, and they are related to the presence of low-wavenumber vibrations in the Raman spectrum. Furthermore, a loose embryonic structure of the Bi2ZnOB2O6 crystal is observed near the crystal–solution interface owing to the formation of Bi–O bonds. Therefore, this study successfully provides a clear understanding of the formation mechanism of Bi2ZnOB2O6 crystals.

Accelerated inter/intra-layer electron transport by asymmetric metal site induced delocalization effect for photoelectrocatalytic water oxidation

Charge transfer at the primary catalyst, co-catalyst, and solution interface is fundamental for photoelectrocatalytic water oxidation. In this paper, we propose a strategy to create a co-catalyst comprised of zinc-cobalt diatomic sites on a nitrogen-doped carbon matrix (CoZn-NC) and load it on BiVO4, called CoZn-NC/BVO. Asymmetrically-doped nitrogen-carbon layer materials of Zn and Co (CoZn-NC) can enable the unrestricted mobility of lone pairs of electrons in metals upon exposure to light irradiation, which results in interlayer polarization and electron delocalization effects, leading to improved charge separation efficiency. Furthermore, due to the synergistic effect of bimetallic doping, not only does the intralayer polarized electric field formed on the surface of CoZn-NC improve the charge injection efficiency, but it also modulates the d-band center of the active site Co, thus reducing the Gibbs free energy of the reaction. The results show that the oxygen reduction reaction of CoZn-NC/BVO is excellent, with a photocurrent density of 5.84 mA cm−2 at 1.23 V vs. RHE, which is 4.35 and 2.1 times higher than that of BiVO4 and Co-NC/BVO, respectively. The charge separation and charge injection efficiencies were also significantly higher, at 84.89 % and 91.97 %, respectively. Overall, the proposed co-catalyst of CoZn-NC/BVO shows great potential in photoelectrocatalytic water oxidation and provides a valuable contribution to the field.

Effects of polar fractions on interfacial and bulk properties at the oil/carbonated aqueous solution interface: Insight from molecular dynamics simulation

This study utilized molecular dynamics simulations to understand the liquid/liquid interfaces in a natural environment involving carbon dioxide and various acidic components. The aim is to unravel the impact of polar fractions with various chemical structures and functional groups, namely benzoic acid, decanoic acid, phenol, and decanol, on the interfacial phenomena of the oleic phase (decane) in contact with water or CO2-rich water at the molecular resolution. The findings indicate that carbon dioxide molecules enrich at the decane/water interface before dissolving into the oleic phase. When polar molecules are introduced to the oleic phase, there is a competition between carbon dioxide and acidic components to accumulate at the interface. The functional hydrocarbon fractions displace carbon dioxide at the interface and bridge the oleic and aqueous phases, reducing interfacial tension. Polar components change the charge distribution of water molecules in the biphasic system, signifying that the organized water layer at the interface with the non-aqueous phase has been disrupted. In contrast to the polar molecules, the carbon dioxide tends to diffuse into the oleic phase and changes the bulk properties like oil fluidity. Accordingly, the fluidity of the decane exhibited significant enhancement by CO2 diffusion throughout the bulk oil phase, which might lead to substantial viscosity reduction.

Deep eutectic solvent-treated palm oil mill sludge adsorbents for methylene blue adsorption.

This study evaluated the adsorptive properties of deep eutectic solvent (DES)-treated palm oil mill sludge adsorbents for methylene blue removal. The adsorbents were prepared at a ratio of 1:2 at 80°C to form P1:D2@80°C, at 25°C to form P1:D2@25°C and without DES to form dry sludge (DS). The adsorbent samples were characterized for surface functional groups, textural properties and surface morphology. The values of specific area were 534, 236 and 184 m2/g, respectively. Batch adsorption of methylene blue at varying concentration, adsorbent dosage, pH, contact time and temperature was performed. The maximum adsorption capacities by Sips model were recorded as 72.07, 56.18 and 48.33 mg/g for P1:D2@80°C, P1:D2@25°C and DS, respectively. P1:D2@80°C displayed the highest rate constant (Ks = 0.0037 g/mg.min). The adsorption data were well fitted into Sips isotherm and pseudo-second-order kinetic models, suggesting that the adsorption is a physical process onto heterogeneous adsorbent surface via pore filling and electrostatic attraction. The adsorption was spontaneous, feasible and exothermic with decreased disorderliness in the solid-bulk solution interface. The DES-treated palm oil mill sludge adsorbent is a promising alternative adsorbent for dye removal from wastewater.

Promoting the adsorption of saponins at the hydrophilic solid-aqueous solution interface by the coadsorption with cationic surfactants

HypothesisSaponins are highly surface active glycosides, and are extensively used to stabilise emulsions and foams in beverages, foods, and cosmetics. Derived from a variety of plant species these naturally occurring biosurfactants have wider potential for inclusion in many low carbon and or sustainably sourced products. Although their adsorption at the air-solution and liquid–liquid interfaces has been extensively studied, the nature of their adsorption at solid surfaces is much less clear. The aim of this study was to establish the criteria for and nature of the adsorption of saponins at both hydrophilic and hydrophobic solid surfaces. ExperimentsAdsorption at the hydrophilic and hydrophobic solid surfaces was investigated using neutron reflectivity. Measurements were made for the saponins escin, quillaja and glycyrrhizic acid. At the hydrophilic surface measurements were also made for escin / cetyltrimethyl ammonium bromide, C16TAB, mixtures; using deuterium labelling to determine the surface structure and composition. FindingsAt a range of solution concentrations, from below to well in excess of the critical micelle concentration, cmc, there was no saponin adsorption evident at either the hydrophilic or hydrophobic surface. This implies an inherent incompatibility between the surface OH– groups at the hydrophilic surface and the saponin sugar groups, and a reluctance for the hydrophobic triterpenoid group of the saponin to interact with the octadecyltrichlorosilane, OTS, hydrophobic solid surface. Above a critical composition or concentration escin / C16TAB mixtures adsorb at the hydrophilic solid surface; with a surface composition which is dominated by the escin, and a structure which reflects the disparity in the molecular arrangement of the two surfactant components. The results provide an important insight into how cooperative adsorption can be utilised to promote adsorption of saponins at the solid- solution interface.

Electrocatalytic Mechanisms for an Oxygen Evolution Reaction at a Rhombohedral Boron Monosulfide Electrode/Alkaline Medium Interface.

Rhombohedral boron monosulfide (r-BS) with a layer stacking structure is a promising electrocatalyst for an oxygen evolution reaction (OER) within an alkaline solution. We investigated the catalytic mechanisms at the r-BS electrode/alkaline medium interface for an OER using hybrid solvation theory based on the first-principles method combined with classical solution theory. In this study, we elucidate the activities of the OER at the outermost r-BS sheet with and without various surface defects. The Gibbs free energies along the OER path indicate that the boron vacancies at the first and second layers of the r-BS surface (VB1 and VB2) can promote the OER. However, we found that the VB1 is easily occupied by the oxygen atom during the OER, degrading its electrocatalytic performance. In contrast, VB2 is suitable for the active site of the OER due to its structure stability. Next, we applied a bias voltage with the OER potential to the r-BS electrode. The bias voltage incorporates the positive excess surface charge into pristine r-BS and VB2, which can be understood by the relationship between the OER potential and potentials of zero charge at the r-BS electrode. Because the OH- ions are the starting point of the OER, the positively charged surface is kinetically favorable for the electrocatalyst owing to the attractive interaction with the OH- ions. Finally, we qualitatively discuss the flat-band potential at a semiconductor/alkaline solution interface. It suggests that p-type carrier doping could promote the catalytic performance of r-BS. These results explain the previous measurement of the OER performance with the r-BS-based electrode and provide valuable insights into developing a semiconductor electrode/water interface.

Scalable fabrication of textile-based planar-structured supercapacitors with excellent capacitive performance

The researchers have been engaged in the development of textile-based high-performance flexible energy storage devices. The conventional fabrics are transformed into electrode composites by uniformly depositing polypyrrole (PPy) coating onto them using a simple interfacial solution polymerization method. The traditional textiles encompass cellulose fabrics such as cotton and ramie, protein fabrics like silk and wool, as well as chemical fiber fabric including polyester, polyamide, and acrylon. The PPy can be effectively coated onto the surface of cellulose fibers and penetrate into their interior, resulting in significantly higher loading capacity on cotton and ramie fabrics compared to other types of fibers. The two fabric electrodes (cotton@PPy and ramie@PPy) have better capacitive properties, especially the areal capacitance of ramie@PPy reaches 2836 mF cm−2. The PPy-coated fabric is precisely divided into standardized interdigital electrodes of consistent dimensions through the utilization of laser cutting techniques. The fabrication of a planar supercapacitor can be achieved through the straightforward assembly of two interdigital electrodes. The planar supercapacitor based on ramie@PPy shows a maximum energy density of 8.21 μWh cm−2 at power density of 0.20 mW cm−2. After undergoing 5000 cycles, the device demonstrates a remarkable ability to retain 90 % of its initial capacitance. The assembled supercapacitors exhibit exceptional flexibility and practicality, enabling power supply to electronic devices when connected in series. The fabric-based flexible supercapacitor can be easily mass-produced, making it a promising candidate for flexible energy storage devices.

Dimethylpiperazine on Air-Water Interface: Vibrational Sum frequency Generation study of a cyclic tertiary amine

Dimethyl piperazine (DMP) is a weakly basic, cyclic, tertiary diamine. Being a saturated 6-membered ring, it may attain a number of energetically close conformational orientations in the ground state. In a particular environment, its conformational distribution depends on the stabilising factors present in the surroundings. Though soluble in water, it is expected to have substantial surface propensity due to presence of multiple –CH2 and –CH3 bonds. Detection of Bohlmann bands in the C–H stretch region of the Vibrational Sum Frequency Generation (VSFG) spectrum revealed that comparatively higher energy chair conformer with one axial and one equatorial –CH3 bond is present on the pure liquid DMP-air interface. At the air-aqueous solution interface, those bands were found to disappear as the lone electron pair on N-atom is engaged in hydrogen bonding with water molecule. Due to this hydrogen bonding, the peak of “dangling free OH” bonds disappeared from VSFG spectrum of water molecules at air–water interface. Alongwith this hydrogen bonding, the hydrophobic nature of the –CH3 bonds of DMP molecules cause disorganisation of native hydrogen bonded network of water molecules in the air–water interface. Structure and orientation of DMP is expected to be pH-responsive since the chemical conditions of the surrounding medium directly affect the extent of protonation of the amine group. Upon addition of HCl to the bulk, protonated DMP ions, too, could be detected on the air-solution interface by their VSFG spectrum which were considerably different from unprotonated DMP. As the bulk pH of solution changed towards more acidic, spectral features of VSFG spectra of DMP on the surface showed significant change, implying variation in the surface pH, as structure and orientation changes at different degrees of protonation. Since the VSFG spectral features of DMP was found to be pH-responsive, it can be utilised to ascertain the pH of any surface that has DMP absorbed on it. pH-sensitivity of the DMP molecules on air–water interface also suggest that orientation of headgroups will have some effect on the surface orientation of cationic surfactants with amine based headgroups.

Assessing the potentials of free base and gallium metalated tertbutylphthalocyanines as aluminium corrosion inhibitors

The adsorption behaviors of 2,9,16,23 tetrakis(4-(tert-butyl)phenoxy)phthalocyanine (1) and gallium (III) 2,9,16,24 tetrakis(4-(tert-butyl)phenoxy)phthalocyanine (2) were studied as corrosion inhibitors at the aluminum−HCl solution interface. In addition to weight loss (gravimetric) and electrochemical methods, the study includes measurements utilizing scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and X-ray diffraction. The findings of the characterization show that the inhibitor molecules were well adsorbed on the aluminum surface, supporting the gravimetric and electrochemical measurements. At 28 °C and the greatest inhibitor concentration (10 μM), the potentiodynamic polarization method gave inhibition efficiency values of 95.2% (1) and 89.1% (2). These compounds showed good corrosion inhibition efficiencies as mixed-type corrosion inhibitors, but they also had a significant anodic character. Theoretical simulations produced conclusions that closely match experimental data.

A conjugated Donor-acceptor blend passivation interlayer for the high-performance carbon-based perovskite solar cells

The interfacial properties between perovskite active layer and carbon electrode significantly affects the energy conversion efficiency and stability of carbon-based perovskite solar cells. In this work a conjugated Donor-Acceptor blend with a dendrite shaped copper phthalocyanine derivative 8TPAEPC as a donor (D) and Y6 as a typical acceptor (A) was designed to enhance the carrier extraction across the perovskite/carbon interface. The respective D and A molecules form strong interactions with I− and Pb2+ on the surface of perovskite by rich functional group atoms, which can synergistically passivate the non-radiative defects. Moreover, the dipoles from D-A coupling construct a strong internal built-in electric field for further suppression of the unwanted recomination. Compared with 8TPAEPC, 8TPAEPC-Y6 blend exhibits the faster charge interface transfer dynamics. Consequently, Carbon-based perovskite solar cells (C–PSCs) optimized by 8TPAEPC-Y6 achieve champion power conversion efficiency (PCE) of 17.07%, superior to those with 8TPAEPC (16.08%), Y6 (15.68%) and pristine perovskite (14.06%). Meanwhile, the C–PSCs with the hydrophobic 8TPAEPC-Y6 blend greatly improved moisture long-term stability that over 90% PCE could remain as long as 90 days. This work finds out an innovative D-A blend interfacial solution for achieving highly efficient and stable C–PSCs.

Noise Spectroscopy Analysis of Ion Behavior in Liquid Gate‐All‐Around Silicon Nanowire Field‐Effect Transistor Biosensors

AbstractThe transport and noise properties of fabricated, high‐performance, gate‐all‐around silicon liquid‐gated nanowire field‐effect transistor devices are investigated in different concentrations of MgCl2 solutions. The critical concentration of MgCl2 solution for charge inversion at the solid‐liquid interface is verified using noise spectroscopy and confirmed using the capacitance‐voltage measurement technique. In this study, it is found that the Hooge parameter (αH) and the equivalent input noise (SU) can effectively reflect the ion behavior on the surface of the nanowire. Moreover, the noise curves for αH and SU indicate two turning points at concentrations of 10−4 and 10−1 m for a peak and a valley, respectively. The noise transformation is related to the behavior of ions near the solid‐liquid interface in solutions with different MgCl2 concentrations is revealed. The results show that noise spectroscopy is a powerful method for monitoring charge dynamic processes in the research field of biosensors.

Spin-dependent charge transmission through chiral 2T3N self-assembled monolayer on Au.

A gold surface is functionalized by chemisorption of the enantiopure N,N'-bis-[2,2';5',2″]tert-thiophene-5-yl methylcyclohexane-1,2-diamine (2T3N), a chiral oligothiophene derivative, via overnight incubation in a 2T3N ethanol solution. The Au|2T3N interface is characterized by x-ray photoelectron circular dichroism and comparing x-ray photoemission spectroscopy and electro-desorption results. Charge transmission at the Au|2T3N| solution interface is characterized by recording the cyclic voltammetry of the Fe(III)/Fe(II) reversible redox couple, finding a charge transfer rate constant, k°, variation from 1 × 10-1 to 3.3 × 10-2 cm s-1, when comparing the bare Au and the Au|2T3N interfaces, respectively. The "anomalous" high value of k° found for the chiral Au|2T3N interface can be rationalized on the basis of the chiral-induced spin selectivity effect, as further proved by magnetic-conductive atomic force microscopy measurements at room temperature. A spin polarization of about 30% is found.

Just laser irradiation of silver benzoate water solution — A direct way of Ag nanofibers synthesis for broadband SERS detection

Highly efficient, homogeneous and reproducible substrates for surface enhanced Raman spectroscopy (SERS) are in high demand for practical broadband sensing and the detection of various analytes. The most promising SERS structures in terms of morphology are nanofibers, forming homogeneous coatings with broadband electric field enhancement. However, existing synthesis methods for the formation of nanofibers are multistage, requiring the preliminary synthesis of templates, using additional components, such as surfactants and capping agents, species extraction from the reaction mixture, washing and sedimentation onto a substrate. Here, we present a simple and scalable synthesis approach allowing the fabrication of long winding silver nanofibers directly on a substrate surface, without any additional stages. The process proposed is ecologically friendly and based on laser irradiation of a substrate–solution interface using a low intensity continuous wave unfocused laser beam with a wavelength of 448 nm. As the liquid phase, a silver benzoate water solution without any additional chemicals was used. The deposited nanofibers formed a continuous coating with an area corresponding to the laser beam, ca. 3 mm2, and were characterized by an enhancement factor as high as 107 in the broad spectral region, a low experimental detection limit of 10−11 M and high reproducibility of the SERS signal with a variation of ∼10%.

Fabrication of Pb-Co-ZrO2 nanocomposite coatings and correlation of corrosion mechanisms with electronic work functions

It is still an urgent task to design metal coatings for the development of corrosion resistance. Herein, Pb-Co-ZrO2 coating is fabricated on the surface of aluminum plates via one-step pulsed electrodeposition for corrosion resistance. The pulse frequency, current density and duty cycle are 800 Hz, 15 mA cm−2 and 20 %, respectively. In this work, the concentration of ZrO2 nanoparticles in the bath is the main operating variable. We further explored the deposition mechanism of the nanocomposite coating and demonstrated its application potential in corrosion resistance. As expected, the corrosion resistance and mechanical properties of the coatings increased and then decreased with the increase of the concentration of ZrO2 nanoparticles in the plating solution. When the concentration of ZrO2 nanoparticles in the plating solution was 15 g L−1, the Pb-Co-ZrO2 nanocomposite coating exhibited excellent corrosion resistance in 3.5 wt% NaCl solution, with an impedance modulus value (5182 Ω cm2) that was eight times higher than that of the pure Pb coating (669 Ω cm2), possessed the highest corrosion potential (- 0.60 V) and the lowest corrosion current density (3.6 μA cm−2), while also exhibiting excellent mechanical properties. The mechanism of the improved corrosion performance of the Pb-Co-ZrO2 composite coatings was further explained using DFT calculations. The results show that the coupling between the interface of Pb-Co solid solution and ZrO2 nanoparticles effectively improves the overall electron figure of merit of the coatings and triggers an obvious electron localisation, which increases the energy required for the interfacial electrons to escape from the coating interface.

Enhancing Gallery Experiences Through Interactive Apps: A Pathway to Democratizing Art Appreciation

To enhance the visitor experience at the Stanley & Audrey Burton Gallery, the author endeavors to develop an Augmented Reality (AR) application. This article initially engages in data collection, employing diverse research methodologies, wherein visitors serve as the subjects of the study. Subsequently, an extensive examination of several analogous gallery apps presently available in the market is conducted through case studies. Ultimately, the article presents three distinct user interface solutions subjected to user testing. This iterative design process expounds on the application’s development and establishes a robust groundwork for enhancing its ultimate iteration.

Thin layer sonoelectrochemistry: Impact on slow heterogeneous electron transfer

In thin layer sonoelectrochemistry (TLS), constructive interference is established in a thin layer of electrolyte with a low power, ultrasonic quartz crystal oscillator (QCO). No cavitation, no temperature increase, and no impacts on mass transport are observed. In this first report of TLS experiments without cavitation, voltammetric morphologies are not disrupted. Interfacial electron transfer for three transition metal species are evaluated with established cyclic voltammetric diagnostics. For Ru(bpy)32+ with inherently fast (reversible) interfacial electron transfer, voltammograms are unchanged on sonication at 41 kHz. For Fe3＋ with slow heterogeneous electron transfer, interfacial rate increases with sonication, where increases in rate persist without diminution for minutes postsonication. For a cobalt phenanthroline probe, changes in voltammetric morphology at higher QCO intensity are consistent with chemical changes of ligand loss. Constructive interference in TLS imparts sound pressure to the electrode solution interface to increase electron transfer rates without mass transport disruption. TLS may provide means to electrocatalyze interfacial rates.

EFFECT OF MECHANOCHEMICAL PROCESSING PARAMETERS ON ETHOXYLATION OF BENZOIC ACID DERIVATIVES

The regularities of ethoxylation of benzoic acid derivatives during interaction with polyethylene glycol through mechanochemical solid-phase synthesis in a vibrating apparatus have been studied. The conditions for carrying out mechanochemical reactions to increase the conversion degree of initial reagents into reaction products are analysed. The products of ethoxylation are characterized by IR spectroscopy, acid-base potentiometric titration, tensiometry, and dilatational rheology. It has been established that the degree of starting reagents conversion into ethoxylation products depends on the nature of the substituent and its position in the benzene ring. The degree of conversion into reaction products is higher for ortho-substituted derivatives of benzoic acid. It is shown that the salts of ethoxylated derivatives of benzoic acid exhibit pronounced surfactant properties at the air - solution interface.