Gibbs Free Energy Of Reaction Research Articles

Some issues in reactive wetting at high temperatures described by reaction product control theory

The phenomenon of reactive wetting at high temperature and its special issues are systematically discussed, focusing on the wetting behavior in metal/metal and metal/ceramic systems. Especially, based on the reaction product control (RPC) theory, the influence of wetting mechanism, spreading dynamics and interfacial reactivity on wettability and interfacial structure is deeply analyzed. The limitations of the classical RPC model under certain conditions are pointed out. In the ultra-fast spreading systems, the spreading dynamics cannot satisfy the prediction of RPC model, which is related to the formation of chemical bonds at the solid/liquid interface. Among them, the Gibbs free energy of the interface reaction does not directly point to the difference of wettability, but is reflected in the thickness of the reaction product layer. The greater the absolute value of Gibbs free energy of interface reaction, the thicker the thickness of precipitation layer. The mechanism leading to wetting is not always consistent with the spreading dynamics, the former is related to the bonding properties, and the latter is related to the slowest link leading to spreading.

Effect of Ti on the properties of diamond microcrystals synthesized in C–O–H supercritical fluid at high pressure and high temperature

Diamond micropowders 1–10 μm were synthesized at 7.5 GPa, 1300–1500 °C, and 3–6 s. Detonation nanodiamonds and pentaerythritol (C5H8(OH)4) with the addition of Ti were used as the reaction medium. The total nitrogen concentration, determined by electron paramagnetic resonance (EPR) and infrared (IR) spectroscopies, in diamonds synthesized without the addition of Ti was 1700 ppm. In diamonds synthesized with the addition of Ti, there are no 2N (A-center) and N3VH0 centers as well as oxygen-related functional groups, and the total concentration of nitrogen centers is reduced to 640 ppm. The addition of Ti leads to an increase in the synthesis temperature by 100–200 °C.Thermodynamics model calculations of the equilibrium compositions of the reaction medium at a pressure of 7.5. GPa and temperatures of 500, 1000 and 1500 °C were performed. The Gibbs free energy of possible reactions between the components of the reaction medium was calculated. It has been shown that under equilibrium conditions and a reaction medium corresponding to the synthesis conditions, the formation of TiN is thermodynamically possible. This leads to a decrease in the nitrogen concentration in diamonds. However, the formation of TiO2 is a competing reaction that can lead to a decrease in the concentration of oxygen-related functional groups.

Selective separation and recovery of valuable metals through directional vulcanization of black copper sludge

The recovery of copper (Cu) from secondary sources has emerged as a promising trend in the copper industry’s advancement. Black copper sludge (BCS), a valuable hazardous waste produced during Cu electrolytic refining, contains various precious metals, including Cu3As. This study investigates theoretical and experimental aspects using BCS as a raw material to mitigate solid waste emissions and retrieve valuable metals. The proposed method for separating Cu from As through directional sulfidation offers an environmentally friendly solution. Gibbs free energies of the sulfidation reaction between BCS and S were calculated using HSC Chemistry 9.0, with experimental validation confirming the method’s feasibility. The study explores the effects of vulcanization temperature, holding time, and S content during the vulcanization reaction. Under optimal conditions of 873 K temperature, 60 min holding time, and 20 % excess S, Cu existed as Cu2S in the sulfide residue, while As2O3 was observed as a condensate. Cu and As recovery rates were 98.38 % and 84.62 % respectively, with a 99.98 % removal efficiency for Cu volatiles and 94.36 % for As residue. This method effectively separates Cu and As from solid wastes containing As, offering a simpler and more environmentally friendly alternative to traditional pyrometallurgical and hydrometallurgical methods. The study presents a novel, eco-friendly, and highly efficient approach for the safe disposal of As-containing solid waste.

GeC/SnSe2 van der waals heterostructure: A promising direct Z-scheme photocatalyst for overall water splitting with strong optical absorption, high solar-to-hydrogen energy conversion efficiency and superior catalytic activity

To alleviate the energy crisis and achieve green energy conversion, the heterojunctions that can be applied to the photocatalytic decomposition of water have attracted attention. In this paper, we design a novel two-dimensional GeC/SnSe2 heterostructure and investigate in detail the structural stability, electronic characteristics, photocatalytic activity and optical behavior as well as the effects due to the applied strain based on the first-principles. Firstly, the most stable γ-stacking mode is determined by combining energy comparison, thermodynamic and dynamic studies. Second, the analysis of electronic properties demonstrates that the GeC/SnSe2 heterostructure exhibits a type-II energy band arrangement and a direct Z-scheme photocatalytic mechanism. This pivotal aspect enhances the separation of photogenerated carriers at the interface and facilitates the active participation of the most proficient materials in oxidation-reduction processes during photocatalytic hydrolysis reactions. The hydrolysis reaction's Gibbs free energy shift demonstrates the GeC/SnSe2 heterostructure's superior photocatalytic activity in neutral and alkaline environments and can spontaneously carry out the overall hydrolysis reaction, and this outstanding ability is not affected by the −4% to 4% strain range. In addition, the GeC/SnSe2 heterostructure has outstanding solar-to-hydrogen efficiency (58.18%) and excellent light absorption capability (up to 4×105cm−1) within visible light. The implications of these discoveries point towards the direct Z-scheme GeC/SnSe2 heterostructure holds promise as an excellent candidate for photocatalytic water splitting applications.

Screening for electrocatalytic reduction of N2 by borophene supported bimetallic atoms

Ammonia (NH3), as a high energy density chemical and hydrogen energy storage medium, has garnered significant interest in the realms of energy storage and catalysis. In contrast to the traditional Haber-Bosch process, the electrocatalysis nitrogen reduction reaction (eNRR) can synthesize green ammonia under mild reaction conditions. Based on density functional theory (DFT), the potential of 2D borophene supported transition metals as bimetallic atomic catalysts (BACs) in eNRR was investigated. Progressive screening through energy-oriented screening mechanism, Sc2B12, Ti2B12, V2B12 and Zr2B12 were identified as potential eNRR catalysts. Their complete reaction pathways and Gibbs free energy (ΔG) were further explored, and corresponding overpotentials were obtained. The results showed that overpotentials of the potential determining steps (PDS) of these catalysts were 0.34, 0.40, 0.39 and 0.13 V, respectively, demonstrating excellent eNRR catalytic activity and good selectivity. Cu2B12 shows remarkable hydrogen evolution reaction (HER) catalytic activity with an overpotential (η) of only 0.05 V. The study also revealed that the catalytic activity of TM2B12 is derived from its excellent conductivity, and the charge transmission enhances the catalyst activity of eNRR. Consequently, this study provides significant theoretical guidance and support for the synthesis of novel eNRR catalysts, and promotes further advancement in the field of catalysis.

Synergistic effects of Fe and P doping in WS2 monolayers for enhanced bifunctional electrocatalysis in water splitting

The quest for efficient dual-purpose electrocatalysts to facilitate water splitting is an ongoing challenge in materials science. In this study, we introduce a novel approach involving the incorporation of Fe and P atoms into WS2 monolayers (MLs) through rigorous first-principle calculations. The introduction of Fe and P atoms brings about remarkable enhancements in the electronic properties of the WS2 MLs, significantly boosting the catalytic performance of the 1T’ phase. The doping-induced changes in energy levels lead to the formation of a spin-polarized density of states, which exhibits superior conductivity in the vicinity of the d-band center and Fermi level. These electronic alterations are intricately governed by the valence and conduction bands. In addition to this, the introduced dopants elevate the charge transfer rate while simultaneously reducing interfacial resistance. Furthermore, the strong bonding of the dopants plays a pivotal role in reducing the energy barrier during adsorption. This, in turn, leads to a substantial decrease in the Gibbs free energy (0.101 eV) for the hydrogen evolution reaction and a lowered overpotential (0.36 V) for the oxygen evolution reaction. These findings collectively offer a promising avenue for the development of advanced bifunctional catalysts in the context of water splitting, suggesting that substitutional heteroatom doping of 1T′-WS2 MLs holds substantial potential in this field.

Modulating space charge of FeP/CoP p-n heterojunction for boosting oxygen evolution reaction

Surface reconstruction of electrocatalysts is an effective strategy to modulate the space charge distribution to enhance the electrocatalytic activity. The p-n heterostructured FeP/CoP-2D octagonal nanoplates were successfully constructed by cation-exchange method. The space charge effect caused by the p-n heterojunction accelerated the electron transfer, optimized the electronic structure, and improved the activity of the active sites during the oxygen evolution reaction process. As a result, FeP/CoP-2D required only 247 mV overpotential to achieve a current density of 10 mA cm−2 with a Tafel slope as low as 68 mV dec-1. Density-functional theory calculations confirmed that the construction of p-n heterojunctions can enhance the adsorption of *OH in the active centers and optimize the Gibbs free energy of the OER reaction. This study provides an effective and feasible strategy for constructing p-n heterojunctions to modulate the space charge state for optimizing the OER performance of electrocatalysts.

Regulation of electron delocalization between flower-like (Co, Ni)-MOF array and WO3/W photoanode for effective photoelectrochemical water splitting

A stable heterometallic (Co, Ni)-MOF array with a 3D hierarchical flower-like morphology was coated onto the coral-like WO3/W thin film. The optimal (Co, Ni)-MOF/WO3/W photoanode exhibits a high photocurrent density of 2.96 mA cm−2 at 1.23 V in the 0.5 M Na2SO4 solution and the photoelectrochemical (PEC) cell displays an excellent solar-to-hydrogen (STH) efficiency (2.17 %) under AM 1.5 G solar light. Moreover, the separation behavior and spatial distribution of photogenerated charges have been demonstrated by photo-assisted Kelvin probe force microscopy (KPFM). Furthermore, the shift of the d-band center and the change of Gibbs free energy for oxygen evolution reaction (OER) are realized by density functional theory (DFT) calculations. Overall, the coupling effect of these ions of Co2+, O2−, Ni2+, and W6+ could result in an electron delocalization in the (Co, Ni)-MOF/WO3/W photoanode, boosting the OER activity and finally improving the PEC water splitting performance.

Study on the Mechanism of Lipid Peroxidation Induced by Carbonate Radicals.

Based on the reported research, hydroxyl radicals can be rapidly transformed into carbonate radicals in the carbonate-bicarbonate buffering system in vivo. Many of the processes considered to be initiated by hydroxyl radicals may be caused by carbonate radicals, which indicates that lipid peroxidation initiated by hydroxyl radicals can also be caused by carbonate radicals. To date, theoretical research on reactions of hydrogen abstraction from and radical addition to polyunsaturated fatty acids (PUFAs) of carbonate radicals has not been carried out systematically. This paper employs (3Z,6Z)-nona-3,6-diene (NDE) as a model for polyunsaturated fatty acids (PUFAs). Density functional theory (DFT) with the CAM-B3LYP method at the 6-311+g(d,p) level was used to calculate the differences in reactivity of carbonate radicals abstracting hydrogen from different positions of NDE and their addition to the double bonds of NDE under lipid solvent conditions with a dielectric constant of 4.0 (CPCM model). Grimme's empirical dispersion correction was taken into account through the D3 scheme. The energy barrier, reaction rate constants, internal energy, enthalpy and Gibbs free energy changes in these reactions were calculated With zero-point vibrational energy (ZPVE) corrections. The results indicated that carbonate radicals initiate lipid peroxidation primarily through hydrogen abstraction from diallyl carbon atoms. The reaction of hydrogen abstraction from diallyl carbon atoms exhibits the highest reaction rate, with a reaction rate constant approximately 43-fold greater than the second-ranked hydrogen abstraction from allyl carbon atoms. This process has the lowest energy barrier, internal energy, enthalpy, and Gibbs free energy changes, indicating that it is also the most spontaneous process.

Mechanisms controlling albite dissolution/precipitation kinetics as a function of chemical affinity: New insights from experiments in 29Si spiked solutions at 150 and 180 °C

Knowledge of the rates of dissolution of rock-forming minerals close to equilibrium and their dependence on ΔGr, the Gibbs free energy of reaction, is essential for describing the temporal and spatial evolution of many environmental and engineering processes involving solid/fluid interactions. In the present study we used the isotope-doping method to quantify albite forward and net dissolution rates. Batch experiments were performed at 150, 180 °C and pH = 9 at near equilibrium and equilibrium conditions (-25 ≤ ΔGr ≤ + 8.2 kJ/mol) in 29Si spiked solutions which were undersaturated with the secondary Al-Si solid phases likely to precipitate.The forward dissolution rates normalized to the initial BET surface area were found to decrease continuously and monotonically with increasing time and ΔGr, achieving values 1.3 to 2.4 orders of magnitude lower at chemical equilibrium than initial far from equilibrium values, with the highest rate decrease for the highest solid to fluid ratio. These rate drops were accompanied by an increase in BET specific surface areas associated with the formation of widespread dissolution features. A decrease of albite forward dissolution rate together with an increase of its BET surface area was also observed as a function of reaction time at far from equilibrium conditions (ΔGr ≤ − 65 kJ/mol). These observations are consistent with a continuous decrease with time and increasing ΔGr of albite effective surface area linked to the formation of unreactive negative crystal facets, in addition to etch pits stopping nucleating above a critical value of ΔGr. Thus, the observed decrease in albite dissolution rate as equilibrium is approached is not linked primarily to the increase in the contribution of the backward reaction but rather to the decrease of the forward reaction rate in conjunction with the decrease in the density of reactive sites at the mineral surface.The results of this study show that the characterization of the effective surface area and its evolution with reaction time and chemical affinity is crucial to deriving robust dissolution rates of well-crystallized minerals like feldspars. Dissolution experiments in 29Si spiked solutions of samples with different history and well-characterized effective surface area and surface morphology should help to better quantify the rate laws controlling silicate minerals weathering.

Silicotungstic acid catalyst supported onto functionalized halloysite nanotubes (HNTs) utilized for the production of 5-hydroxymethylfurfural (5-HMF) from fructose

5-Hydroxymethylfurfural (5-HMF) is a valuable organic compound commonly derived from sugars such as fructose and glucose. Silicotungstic acid (HSiW), a unique Keggin-type heteropolyacid, is a typical catalyst for organic compound production. To synthesize 5-HMF from fructose, we developed a novel catalyst, HSiW@F-HNTs, by combining HSiW and functionalized halloysite nanotubes (F-HNTs) modified with (3-amino-propyl) triethoxysilane (APTES), 2,4,6-trichloro-1,3,5-triazine (TCT), and l-arginine. We analyzed the physicochemical properties of HSiW@F-HNTs using the FT-IR, XRD, BET, FESEM, EDS, and XPS characterization techniques, confirming their suitability for fructose-to-5-HMF conversion. Through response surface methodology (RSM), we investigated and optimized the effects of reaction conditions on 5-HMF production yield. Optimal conditions were found to be a 102 °C reaction temperature, a 65 min reaction time, and an 8.5 wt.% catalyst loading, resulting in a 95 % yield of fructose-to-5-HMF conversion. We also conducted the kinetic and thermodynamic analyses to determine the reaction rate and activation energy (Ea) and estimate the changes in Gibbs free energy (ΔG), enthalpy (ΔH), and entropy (ΔS) of the catalytic conversion reaction. Additionally, the prepared HSiW@F-HNTs catalyst could be recycled up to 9 times without a significant loss in activity, demonstrating its high stability for real-world applications.

Parameterization of the IEF PCM model for calculating solvation energies in N-methylpyrrolidone solution

ABSTRACT Theoretical modelling of N-methylpyrrolidone (NMP) solutions, using a polarisable continuum model (IEFPCM), has been carried out with the aim to find the optimal value of a model parameter, a so-called scaling factor (α) for NMP, which should afford an improved modelling of various N-methylpyrrolidone solutions. Our working protocol comprised evaluations of the Gibbs free energy for the dissociation reaction of a set of 22 acids, employing the B2PLYP-D2/6–311+G**//B3LYP/6–31+G* approach, which were then used to calculate the acidity indices by considering the solvation energy at various values of α within the IEFPCM model. The optimal value of α for the N-methylpyrrolidone solvent has been found to amount to 1.40.

Thermodynamic Inhibition of Microbial Sulfur Disproportionation in a Multisubunit Designed Sulfur-Siderite Packed Bioreactor.

Sulfur disproportionation (S0DP) poses a challenge to the robust application of sulfur autotrophic denitrification due to unpredictable sulfide production, which risks the safety of downstream ecosystems. This study explored the S0DP occurrence boundaries with nitrate loading and temperature effects. The boundary values increased with the increase in temperature, exhibiting below 0.15 and 0.53 kg-N/m3/d of nitrate loading at 20 and 30 °C, respectively. A pilot-scale sulfur-siderite packed bioreactor (150 m3/d treatment capacity) was optimally designed with multiple subunits to dynamically distribute the loading of sulfur-heterologous electron acceptors. Operating two active and one standby subunit achieved an effective denitrification rate of 0.31 kg-N/m3/d at 20 °C. For the standby subunit, involving oxygen by aeration effectively transformed the facultative S0DP functional community from S0DP metabolism to aerobic respiration, but with enormous sulfur consumption resulting in ongoing sulfate production of over 3000 mg/L. Meanwhile, acidification by the sulfur oxidation process could reduce the pH to as low as 2.5, which evaluated the Gibbs free energy (ΔG) of the S0DP reaction to +2.56 kJ, thermodynamically suppressing the S0DP occurrence. Therefore, a multisubunit design along with S0DP inhibition strategies of short-term aeration and long-term acidification is suggested for managing S0DP in various practical sulfur-packed bioreactors.

Janus MSiSnN4(M= Mo; W):High efficiently overall water splitting photocatalyst triggered by the intrinsic electric field

Photocatalytic hydrolysis is one of the most effective ways for hydrogen fuel as a strategy for turning solar energy into hydrogen fuel. Two-dimensional(2D) Janus materials with an out-of-plane polarized electric field not only help to promote photogenerated carrier separation and migration but also alter the alignment of water splitting potentials, which enhances photo-oxidation and retains efficient absorption of visible light. In this manuscript, a systematic first-principles analysis was conducted on the WSn2N4 and MSiSnN4 (M= Mo; W) system. The results show that Janus MSiSnN4 (M= Mo; W) systems have a suitable bandgap and band edge position (span the redox position of water), as well as the ample electron mobility(>200 cm2V−1s−1) and outstanding visible light optical absorption capacity(η’STH = 23.12 % for WSiSnN4; η’STH = 32.91 % for MoSiSnN4). The oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) Gibbs free energy changes of WSiSnN4 show that it can make HER and OER processes occur spontaneously under light in acidic and neutral solutions, demonstrating excellent photocatalytic performance.

Theoretical investigation on the strain engineering control of TiC as tunable high-efficiency bifunctional cathode materials for Lithium–Sulfur batteries

Developing efficient cathode materials and strategies to suppress the shuttle effect and promote the reaction kinetics were the key scientific issues for the development of high performance lithium–sulfur (Li–S) batteries. Modify the properties of a material through strain engineering is an effective strategy to enhance the performance of adsorption and catalysis ability for special species. In this paper, first-principles calculations were carried out to investigate the anchoring effect and electrochemical performance of TiC (001) subjected to biaxial symmetric mechanical (compressive and tensile) strains. The results demonstrate that the adsorption energies of the lithium polysulfides (LiPSs) were enhanced monotonically and the metallic properties were also remaining along with the strain from compressive to tensile . In addition, an appropriate strain could reduce the migration barrier of Li ions, the dissociation barrier of Li2S and the Gibbs free energy of the sulfur reduction reaction (SRR) to realize the rapid charge/discharge processes. Especially, the p-band center of carbon atoms in TiC was proposed as an effective descriptor to identify the adsorption and catalysis ability of the anchoring materials under biaxial strain. Our results indicate that strain engineering is a promising strategy to improve the comprehensive performance of anchoring materials in Li − S batteries.

The Direct Alloying of Steel through Silicothermic Self-Reduction of Chromite Ore Utilizing Si-Containing Solid Waste

Organosilicon materials generate copious amounts of Si-containing solid waste during production, leading to severe environmental pollution and substantial resource squandering. In pursuit of the resource utilization of Si-containing solid waste, this study conducted experimental research on the direct alloying of molten steel through the silicothermic self-reduction of chromite ore using Si-containing solid waste as a reducing agent. Additionally, thermodynamic analysis was performed, employing the thermodynamic calculation software FactSage 8.2 (Thermfact Ltd., Montreal, QC, Canada and GTT-Technologies, Aachen, Germany), to examine the equilibrium reactions of the silicothermic reduction of chromite ore and the variations in the thermodynamic equilibrium compositions of slag and metal phases. The results indicate a reduction sequence for the reducible components in chromite ore as Fe2O3 → Cr2O3. The introduction of CaO and Al2O3 into the silicothermic self-reduction compacts altered the forms of Fe and Cr oxides in equilibrium, significantly reducing the standard Gibbs free energy (ΔG0) of the silicothermic reduction reaction. The initial slag melting point decreased from 1700 °C without the addition of CaO and Al2O3 to 1500 °C with the addition of CaO and Al2O3. Correspondingly, the slag viscosity at 1600 °C decreased from 134.1 Pa·s without CaO and Al2O3 addition to 1.81 Pa·s with CaO and Al2O3 addition. The addition of CaO and Al2O3 accelerated the reduction of Cr oxide in chromite ore and enhanced the recovery of Cr, consistent with the thermodynamic calculation results. In the process of steelmaking through the direct alloying of chromite ore silicothermic self-reduction compacts, the final recovery rate of Cr increased from 86.4% without CaO and Al2O3 addition to 95.4% with CaO and Al2O3 addition.

Development of a Thermodynamically Favorable Multi-enzyme Cascade Reaction for Efficient Sustainable Production of ω-Amino Fatty Acids and α,ω-Diamines.

Aliphatic ω-amino fatty acids (ω-AFAs) and α,ω-diamines (α,ω-DMs) are essential monomers for the production of nylons. Development of a sustainable biosynthesis route for ω-AFAs and α,ω-DMs is crucial in addressing the challenges posed by climate change. Herein, we constructed an unprecedented thermodynamically favorable multi-enzyme cascade (TherFavMEC) for the efficient sustainable biosynthesis of ω-AFAs and α,ω-DMs from cheap α,ω-dicarboxylic acids (α,ω-DAs). This TherFavMEC was developed by incorporating bioretrosynthesis analysis tools, reaction Gibbs free energy calculations, thermodynamic equilibrium shift strategies and cofactor (NADPH&ATP) regeneration systems. The molar yield of 6-aminohexanoic acid (6-ACA) from adipic acid (AA) was 92.3 %, while the molar yield from 6-ACA to 1,6-hexanediamine (1,6-HMD) was 96.1 %, which were significantly higher than those of previously reported routes. Furthermore, the biosynthesis of ω-AFAs and α,ω-DMs from 20.0 mM α,ω-DAs (C6-C9) was also performed, giving 11.2 mM 1,6-HMD (56.0 % yield), 14.8 mM 1,7-heptanediamine (74.0 % yield), 17.4 mM 1,8-octanediamine (87.0 % yield), and 19.7 mM 1,9-nonanediamine (98.5 % yield), respectively. The titers of 1,9-nonanediamine, 1,8-octanediamine, 1,7-heptanediamine and 1,6-HMD were improved by 328-fold, 1740-fold, 87-fold and 3.8-fold compared to previous work. Therefore, this work holds great potential for the bioproduction of ω-AFAs and α,ω-DMs.

Hydrogen production of overall water splitting with direct Z-scheme driven by antimonene and arsenide nanoribbon heterostructures: Insight from electronic properties and carrier nonadiabatic dynamics

Two nanoribbon heterostructures are suitable for driving efficient direct Z-schemes of the photocatalytic overall water splitting for hydrogen production and are screened out of nine heterostructures constructed from edge-passivated antimonene (SbNR-X) and arsenide (AsNR-X, X = F, Cl, CN) nanoribbons. The solar-to-hydrogen (STH) efficiency and the Gibbs free energies (ΔGs) of the redox reactions at different sites are calculated to identify the preferable Z-schemes. Meanwhile, the transfer and recombination of the photogenerated carriers are explored by using nonadiabatic molecular dynamics (NAMD) simulations. The obtained band alignments and built-in electric fields of the two considered heterostructures can match the requirements of the photocatalytic Z-scheme, and the corresponding STH efficiencies can reach 15.04 % and 30.53 %, respectively. The oxidation evolution reactions can proceed spontaneously, and hydrogen evolution reactions are feasible in thermodynamics. NAMD simulations show that the SbNR-CN/AsNR-CN nanoribbon heterostructure has faster interlayer recombination but slower transfer of the photogenerated electron from the SbNR-CN to AsNR-CN nanoribbons and of the photogenerated hole along the reversible direction, indicating that this heterostructure has a higher carrier utilization rate. These findings confirm that the SbNR-CN/AsNR-CN nanoribbon heterostructure is a promising candidate for developing high STH efficiency materials with direct Z-schemes.

Electrochemical screening of selected β-blockers at a polarized liquid-liquid interface.

This paper describes the electrochemical behavior of five β-blockers at the polarized liquid-liquid interface formed between aqueous solution (sodium chloride solution or Britton-Robinson buffers) and bis(triphenylphosphoranylidene)ammonium tetrakis(4-chlorophenyl)borate (BTPPATPBCl) dissolved in 1,2-dichloroethane (the organic phase). All measurements reported in this work were conducted using cyclic voltammetry (CV). The effects of the concentration of analytes, the pH of the aqueous phase, and applied electrochemical parameters on the analytical performance of the studied system are studied and discussed. The linear dynamic ranges (LDRs) of the studied β-blockers were in the range of 5-200 μmol L-1 and the lowest limit of detection (LOD) value was determined for pindolol (LOD = 1.96 μM μmol L-1). The highest LOD value was 4.96 μmol L-1 found for nebivolol. In addition, physicochemical parameters such as the formal Galvani potential difference (Δaqorgϕ), formal Gibbs free energies of the ion transfer reaction (ΔaqorgG') and partition coefficients (log P'aq/org) for all studied molecules were determined. The latter were compared and correlated with the available literature values of log Poctanol. Finally, a standard addition method was used to determine the concentration of nebivolol in pharmaceutical preparations using a platform based on the electrified liquid-liquid interface.

Substitution effect of phenol derivatives on electrochemical oxidation potentials: Correlation of theoretical reaction Gibbs free energies

Abstract Reaction Gibbs free energies for electron abstraction from phenol and its 74 derivatives were calculated using the composite ab-initio approach (G4) in combination with the implicit solvation model. Resulting values were correlated with 38 oxidation potentials obtained from cyclic voltammetry measurements. Substitution effect and the role of substituents in ortho-, meta-, and para-position were also quantified by Hammett constants. The evaluated linear dependences can be used to reliably estimate electrochemical potentials of substituted phenols solvated in water.