Gibbs Free Energy Research Articles

Durable Photo-Pyroelectric Detection in a Diamine-Constructed Lead-Free Hybrid Perovskite Ferroelectric.

As a subcategory of pyroelectric materials, hybrid perovskite ferroelectrics possess substantial pyroelectric properties and exceptional light absorption characteristics, demonstrating significant potential in the photo-pyroelectric (PPE) detection field. Despite the significant advantages of hybrid perovskite ferroelectric materials for PPE detection, both the lead issue and the weak stability from van der Waals interactions in monoamines have hindered their further application. Here, 1D lead-free ferroelectric (BDA)SbBr5 (1, where BDA is 1,4-butanediammonium) is fabricated to achieve PPE detection. Compound 1 exhibits significant symmetry breaking attributed to the order-disorder transition of organic cations and octahedral distortions. Specifically, compound 1 enables broad-spectrum PPE detection from UV to near-infrared (377-980nm) and further realizes switchable pyroelectric current after polarization. More importantly, the stability of the pyroelectric current is preserved without degradation over three months, attributed to the hydrogen bonding interactions of butanediamide. Further theoretical calculations of compound 1 reveal a more negative energy of formation than its monoamine homologs (BA)2SbBr5 (where BA is n-butylammonium), which is evidence of its stability. These findings highlight 1 as a promising candidate for high-stability and environmentally friendly PPE wide-spectrum detection, representing a noteworthy advancement in the ferroelectric field.

Ion Association and Hydration of Some Heavy-Metal Nitrate Salts in Aqueous Solution.

Aqueous solutions of four heavy-metal nitrate salts (AgNO3, TlNO3, Cd(NO3)2 and Pb(NO3)2) have been studied at 25 °C using broadband dielectric relaxation spectroscopy (DRS) at frequencies 0.27 ≤ ν/GHz ≤ 115 over the approximate concentration range 0.2 ≲ c/mol L-1 ≲ 2.0 (0.08 ≲ c/mol L-1 ≲ 0.4 for the less-soluble TlNO3). The spectra for AgNO3, TlNO3, and Pb(NO3)2 were best described by assuming the presence of three relaxation processes. These consisted of one solute-related Debye mode centered at ∼2 GHz and two higher-frequency solvent-related modes: one an intense Cole-Cole mode centered at ∼18 GHz and the other a small-amplitude Debye mode at ∼500 GHz. These modes can be assigned, respectively, to the rotational diffusion of contact ion pairs (CIPs), the cooperative relaxation of solvent water molecules, and its preceding fast H-bond flip. For Cd(NO3)2 solutions an additional solute-related Debye mode of small-amplitude, centered at ∼0.5 GHz, was required to adequately fit the spectra. This mode was consistent with the presence of small amounts of solvent-shared ion pairs. Detailed analysis of the solvent modes indicated that all the cations are strongly solvated with, at infinite dilution, effective total hydration numbers (Zt0 values) of irrotationally bound water molecules of ∼5 for both Ag+ and Tl+, ∼10 for Pb2+, and ∼20 for Cd2+. These results clearly indicate the presence of a partial second hydration shell for Pb2+(aq) and an almost complete second shell for Cd2+(aq). However, the hydration numbers decline considerably with increasing solute concentration due to ion-ion interactions. Association constants for the formation of contact ion pairs indicated weak complexation that varies in the order: Tl+ < Ag+ < Pb2+ < Cd2+, consistent with the charge/radius ratios of the cations and their Gibbs energies of hydration. Where comparisons were possible the present constants mostly agreed well with the rather uncertain literature values.

Nanoporous Metatitanic acid on γ-Al2O3 aerogel for higher CO2 adsorption capacity and lower energy consumption

Carbon dioxide capture has become an important issue in reducing atmospheric heat these days. In this study, adsorption of carbon dioxide by aerogel Gamma Alumina-Metatitanic Acid has been investigated and optimized. Morphological and structural analyses such as BET, FESEM, FT-IR, and XRD have also been conducted. In addition, Response surface methodology has been applied in order to achieve the optimal conditions, using a five-level Central composite design. The highest amount of adsorption, 12.874 (mmol/g), was recorded at a temperature of 20 (°C), pressure of 7 (bar), and 25 (%wt) of Metatitanic Acid. This was approximately 11.46% and 4.84% higher than those of mesoporous MgO and 4Azeolite, respectively. Regeneration of the adsorbent was also studied at different temperatures and process durations. Metatitanic acid, as a catalyst, reduces the temperature and regeneration time of the adsorbent by creating active sites and surface hydroxyl groups. It also lowers the required activation energy and enhances the thermal conductivity of the composite material. The optimal result was achieved at a temperature of 100 (°C) and a duration of 30 (min). Finally, isothermal and thermodynamic experiments were conducted to establish the most accurate predictive model and conditions, including Enthalpy, Entropy, and Gibbs free energy. The results indicate that the Freundlich model aligned well with the laboratory findings. Additionally, the negative values of Enthalpy, Entropy, and Gibbs free energy suggested that the adsorption process was physical, exothermic, and spontaneous.

Efficient phosphate removal from water using ductile cast iron waste: a response surface methodology approach.

Water scarcity is a critical issue worldwide. This study explores a novel method for addressing this issue by using ductile cast iron (DCI) solid waste as an adsorbent for phosphate ions, supporting the circular economy in water remediation. The solid waste was characterized using XRD, XRF, FTIR, and particle size distribution. Wastewater samples of different phosphate ion concentrations are prepared, and the solid waste is used as an adsorbent to adsorb phosphate ions using different adsorbent doses and process time. The removal percentage is attained through spectrophotometer analysis and experimental results are optimized to get the optimum conditions using Design Expert V13. The pseudo-second order (PSO) kinetics model and Langmuir isotherm were fitted with the experimental results with maximum adsorption capacity (qmax = 0.28mg/g). The thermodynamic analysis indicated that this adsorption process was spontaneous based on the negative value of Gibbs free energy (∆G). Additionally, the positive values of enthalpy (∆H) indicated the endothermic nature of this adsorption system. It was able to reach the highest adsorption percentage of 98.9 (%) for phosphate ions from aqueous solutions using response surface methodology (RSM) with optimum conditions of 10mg/L phosphate ion concentration, pH = 8, normal room temperature, 9min adsorption, and 0.5g/L adsorbent dosage.

Controlled synthesis of the M doped (M = Fe, Cu, Zn, Mn)-Co4S3/Ni3S2 catalyst with high electrocatalytic performance for hydrogen evolution reaction in seawater and urea

Electrolysis of seawater is a promising method for producing hydrogen, but sluggish reaction kinetics and electrolyte containing corrosive ions limit its development. In this work, a series of M doped (M = Fe, Cu, Zn, Mn)-Co4S3/Ni3S2 catalyst has been prepared on Ni foam by hydrothermal method with excellent seawater and urea splitting performance. The unique 3D porous structure provides a large number of active sites for the catalyst, which has strong catalytic activity. Fe-Co4S3/Ni3S2 electrode showed excellent hydrogen evolution reaction (HER) catalytic activity in 1 M KOH + seawater and 1 M KOH + 0.5 M urea, driving a current density of 10 mA cm−2 at a low overpotential of 81 and 66 mV. In addition, Fe-Co4S3/Ni3S2 electrode also shows strong stability in 15 h stability test. The results show that although the impurity ions in seawater affect the activity of catalyst, the corrosion resistance of catalyst also improves the catalytic activity and stability. Density functional theory calculations show that this Fe-Co4S material exhibits the optimal Gibbs free energy of hydrogen, the introduction of this Ni3S2 material enhances the electrical conductivity of the material, and the synergistic catalysis of the two materials promotes the optimal hydrogen production performance of the Fe-Co4S3/Ni3S2 material. This work provides a novel understanding for the research of catalysts used in the electrolysis of seawater and urea.

Ligand engineering regulates the electronic structure of Ni-N-C sites to promote electrocatalytic acetylene semi-hydrogenation

Compared with traditional thermal catalytic hydrogenation technology, electrocatalytic acetylene semi-hydrogenation (EASH) is a green and environmentally friendly method. EASH utilizes renewable electricity under normal temperature and pressure conditions, and uses water as a hydrogen source to electrocatalytically semi-hydrogenate acetylene to ethylene. Ni-based single-atom catalysts (SACs) have shown good application prospects in EASH, but there is still much room for optimization. The axial coordination regulation of the active center is a potential means to improve its activity. In this work, the activity and selectivity of NiN4 SACs with 14 axial ligands (X) for EASH were systematically studied via density functional theory (DFT). First, the binding energy and ab initio molecular dynamics simulation results show that all the NiN4-X can exist stably. Second, the Gibbs free energy diagram shows that the activation and adsorption of C2H2 is the rate-determining step of the reaction. The introduction of the –ONO ligand enhances the activation and adsorption of C2H2 by NiN4, which is beneficial to the occurrence of EASH and inhibits the side reactions of hydrogen evolution. The two parameters ΔG∗CHCH and ΔG∗CH2CH3 can be used as characteristic descriptors to predict the activity and selectivity of EASH. Finally, the catalytic activity mechanism was explained from the perspective of electrons and orbitals, and it was found that the dz2 orbital played a leading role in the axial ligand regulation of C2H2 catalytic activity. This work provides a new method for the development of efficient EASH catalysts.

Ingenious regulation and activation of sites in the 2H-MoS2 basal planes by oxygen incorporation for enhanced photocatalytic hydrogen evolution of CdS

The 2H phase of MoS2 has the advantages of stable phase structure and tunable preparation approach, while the unfavorable H adsorption ability at the basal plane sites hinders the H2 evolution performance. Here, we developed an effective strategy for the regulation of the basal plane properties of MoS2 via oxygen doping. It is demonstrated that the Gibbs free energy of hydrogen adsorption (ΔGH*) at the sites in the basal plane can be effectively optimized. Using oxygen-doped MoS2 (OMoS) as a cocatalyst, the constructed OMoS/CdS heterojunction photocatalyst shows a stronger built-in electric field and improved photocatalytic H2 production activity. The optimized OMoS/CdS sample with only 0.3 wt% OMoS loading amount achieved an H2 evolution rate of 58.47 mmol g-1h−1 under AM 1.5 light irradiation, which is significantly superior to that of conventional MoS2 modified CdS and even higher than the 1 wt% Pt modified CdS. Our results not only highlighted the significant potential of OMoS as a photocatalyst for hydrogen production, but also proposed a superior to and effective conception for optimizing the H2 evolution activity at the basal plane sites of 2H-MoS2.

Sustainable synthesis and dual adsorption of methyl orange and cadmium ions using biogenic silica-based fibrous silica functionalized with crown ether ionic liquid

In pursuit of sustainable nanomaterial production, this study presents a novel biogenic fibrous silica sphere functionalized with a crown ether ionic liquid for advanced dual-adsorption of methyl orange and Cd(II) from aqueous solutions. Sorghum waste serves as the silica source in the adsorbent preparation process, ensuring an eco-friendly approach. The benzo-15-crown-5 ionic liquid is coupled to thiol-functionalized fibrous silica spheres through an efficient thiol-ene click reaction. Under constant conditions (temperature: 298 K, solution volume = 50 mL, adsorbent dosage = 5 mg, pH = 7, shaking speed = 200 rpm), the synthesized material demonstrates maximum adsorption capacities of 507.1 mg/g and 306.3 mg/g for methyl orange and Cd(II), respectively, according to the Langmuir model. Thermodynamic investigations reveal endothermic adsorption for methyl orange with an enthalpy change of −77.49 KJ mol−1, while exothermic adsorption is observed for Cd(II) with an enthalpy of +24.10 KJ mol−1. The entropy change of adsorption is −0.153 KJ mol−1 K−1 for methyl orange, indicating a more ordered state, and + 0.192 KJ mol−1 K−1 for Cd(II), suggesting increased disorder. The change in Gibbs free energy ranges from −32.66 to −29.60 KJ mol−1 for methyl orange and −32.29 to −35.99 KJ mol−1 for Cd(II), demonstrating that both adsorption processes are spontaneous. These results indicate that the adsorbent has potential as a dual-adsorption material for water remediation applications.

DNA and hemoglobin binding activities: Investigation of coumarin-thiosemicarbazone hybrids

Coumarin and coumarin-thiosemicarbazone hybrids were synthesized and characterized by various techniques such as FT-IR, 1H NMR, 13C NMR, MALDI-TOF-MS spectroscopy, and single crystal X-Ray diffractometer (XRD). The photochemical and photophysical properties of the compounds, such as solvatochromism, solubility, and chemical reactivity, were analyzed using UV–vis spectroscopy in different solvents. Due to the potential biological activities of the synthesized compounds, their binding affinity and mechanisms with calf thymus DNA (ct-DNA) and bovine hemoglobin (BHb) were determined using several useful spectrophotometric and theoretical approaches such as UV–vis absorption and fluorescence spectroscopy, molecular docking, and density functional theory (DFT). The experimental results showed that the compounds exhibited strong binding interactions with DNA and BHb. Additionally, the compounds demonstrated predominantly binding modes, such as intercalation and groove binding with DNA and π–π stacking interactions with BHb.To better understand the thermodynamics of these interactions, quenching constants, binding constants, and Gibbs free energy changes (ΔG°) were calculated. Molecular docking and DFT results supported the experimental data regarding the binding affinity and mechanisms of the compounds to DNA and BHb. Overall, this comprehensive study on coumarin and coumarin-thiosemicarbazone hybrids provides valuable insights into their interaction mechanisms with critical biomolecules, highlighting their potential in therapeutic applications as multifunctional agents.

Triad photosensitizers based on iodo-aza-Bodipy and naphthalenediimides (NDI) with broadband absorption: Study of resonance energy transfer and electron transfer

Two organic photosensitizers based on resonance energy transfer (A-1 and A-2) are prepared. Naphthalenediimides was used as intramolecular energy donor and iodo-aza-Bodipy was used as intramolecular energy acceptor/spin converter. A-1(ε = 42800 at 618 nm and ε = 59600 at 674 nm) and A-2 (ε = 33300 at 514 nm and ε = 68300 at 674 nm) give the two strong absorption band and both of them show broadband absorption in visible region. The photophysical properties of the compounds were studied with steady state and time-resolved spectroscopy in detail. With steady state and time-resolved spectroscopy, we found that photoexcitation into the energy donor was followed by singlet energy transfer, then via the intersystem crossing (ISC) of the energy acceptor. By nanosecond time-resolved transient absorption spectroscopy and DFT calculation, triplet excited state is localized on the iodo-aza-Bodipy moiety. Quantum yield of singlet oxygen of A-1 and A-2 is 39.7% and 40.9 %, respectively. Based on fluorescence lifetime quenching, the efficiency of intramolecular energy transfer is estimated to be 15.9% and 27.7% for A-1 and A-2. And PET is responsible for the relatively low efficiency, which is identified by the calculation of kcs / kFRET and the Gibbs free energy change(△G0cs). A-1 and A-2 were used for singlet oxygen (1O2) mediated photooxidation of 1,5-dihydroxylnaphthalene and the photosensitizing ability are more efficient than the triplet photosensitizers with the mono-chromophore photosensitizer.

Insights into the Adsorption Mechanism of Chlorpyrifos on Activated Carbon Derived from Prickly Pear Seeds Waste: An Experimental and DFT Modeling Study

The removal of chlorpyrifos (CPF) from water was achieved using activated carbon (AC) derived from prickly pear seeds (PPS) wastes, developed through chemical activation with phosphoric acid. Several physico-chemical characterization methods were employed. The determination of surface functions using the Boehm assay indicated that the processed AC predominantly possesses acidic functions. The results obtained from the Boehm assay were corroborated by the pH value of the point of zero charge (pHpzc), which was equal to 2.5. Specific area calculation by the BET (Brunauer Emmett Teller) method revealed a large specific area (SBET) of 1077.66 m2 g⁻1. Adsorption experiments of CPF on AC demonstrated that the pseudo-second order (PSO) model and the Freundlich model were the most suitable for kinetic and isothermal modeling, respectively. The maximum CPF adsorption capacity of the PPS AC was found to be approximately 35 mg g⁻1. A theoretical study employing the density functional theory (DFT) was conducted using the B3LYP/6-311G (d, p) method. The most reliable adsorption energy (Eads) and Gibbs free energy (ΔGads) values between CPF and the functional groups on the AC surface were calculated. Results indicated a strong interaction between the lactone group of AC and CPF (ΔGads = -7.15 kcal mol⁻1, ΔEads = -21.55 kcal mol⁻1) and the hydroxyl group (ΔGads = -6.61 kcal mol⁻1, ΔEads = -20.66 kcal mol⁻1). This study demonstrates that activated carbon possesses significant adsorption power, making it highly effective for depolluting water contaminated by pesticides. The application of the theoretical DFT method enhances the understanding of the adsorption phenomenon of CPF on AC.

Thermophysical properties: Viscosity, density, and excess properties of 2-propanol and n-Decane mixtures from 283.15 K to 343.15 K under atmospheric conditions

To study the effects of temperature as well as molecular interaction of a fluid system on the thermophysical properties of 2-propanol and n-Decane binary mixture, the density (ρ), dynamic viscosity (η), speed of sound (u), and refractive index (nD) of pure 2-propanol and n-Decane, along with their binary mixtures, were experimentally measured across the entire compositional range at temperatures from 283.15 to 343.15 K and atmospheric pressure. These experimental measurements helped in the evaluation of various thermophysical properties, such as excess molar volume (vE), coefficient of thermal expansion (αE), and isentropic compressibility (κsE). The experimental dynamic viscosity (η) and density (ρ) data were used to evaluate kinematic viscosity (v) and Gibbs free energy (ΔG) of flow with an equation based on Eyring's absolute state theory, and their corresponding excess properties. The excess properties of the binary mixtures were correlated using a Redlich-Kister type polynomial equation via the least-squares regression method, with fitting parameters determined for the binary system. Moreover, the Prigogine–Flory–Patterson theory (PFP) was utilized to identify the primary molecular interactions contributing to the excess molar volume at 293.15, 308.15, and 323.15 K for the binary mixtures. Additionally, the capability of the Eyring-NRTL model was tested to predict the viscosity as well as vapor-liquid equilibrium (VLE) of the binary system, and the correlated model results agreed with literature data.

A colorimetric sensor based on 2,3-bis(6-chloropyridin-2-yl)-6-fluoroquinoxaline for naked-eye detection of Iron (III) and its application in real sample analysis

Iron ions are crucial for numerous biological processes, and the levels of these ions have a significant impact on human well-being. Hence, it is essential to identify the level of Iron ions using a suitable technique. A new colorimetric sensor, namely “2,3-bis(6-chloropyridin-2-yl)-6-fluoroquinoxaline” (CF), has been introduced to detect Fe3+ through naked-eye observation. The sensor exhibits remarkable specificity towards Fe3+ compared to other metal ions in aqueous environments. Furthermore, it undergoes a substantial color change from colorless to yellow, which is visible without needing additional equipment. The complex formation was proposed to be in 1:1 ratio based on the Job’s plot and molar ratio plot. The maximum sensitivity of CF towards Fe3+ was found at pH 6 to 8. Minimal or negligible interference was noticed from different metal ions in the detection of Fe3+. The binding constant using Benesi-Hildebrand was estimated at 1.434 × 104 M−1. Gibbs free energy was determined –23.728 kJ/Mol. The LOD and LOQ were calculated at 0.378 and 1.26 µM, respectively. The probe CF was utilized to recover Fe3+ in tap water, resulting in recovery percentages ranging from 99.44 to 103.61. This indicates that the CF has the ability to identify Fe3+ in environmental samples

An innovative guanidinium-based ionic covalent organic frameworks with abundant aromatic rings for high-efficiency naproxen removal: Adsorption behavior, mechanisms, and density functional theory calculations

In recent years, naproxen (NPX) has raised significant environmental concerns requiring urgent attention. This study presents an innovative guanidinium-based ionic covalent organic framework (TFPB-TgCl), containing abundant aromatic rings, which was successfully synthesized via Schiff base reaction for the efficient and selective removal of NPX. Remarkably, TFPB-TgCl manifested a maximal NPX adsorption capacity of 308 mg/g at pH = 5. The adsorption on the active site (AOAS) model highlighted the simultaneous occurrence of both physical and chemical adsorption during the NPX uptake. The coefficients of the physical adsorption rates (5.6479, 1.9224, and 1.9224 min−1 for NPX concentrations of 20, 50, and 100 mg/L, respectively) were significantly higher than those of the chemical adsorption rates (0.1759, 0.0681, and 0.0567 g·mg−1·min−1 for the same concentrations), indicating the predominance of physical adsorption. Furthermore, the multilayer adsorption (MLA) model suggested that an adsorption site can interact with more NPX molecules, benefiting from various electrostatic and π-π interactions. The negative values of enthalpy change (ΔH° = −11.956 kJ/mol) and Gibbs free energy (ΔG < 0) confirmed the exothermic and spontaneous nature of the adsorption process. Additionally, in the optimal adsorption configuration (−131.57 kcal/mol), the Independent Gradient Model based on Hirshfeld partition (IGMH) was utilized to identify interaction sites between the guanidinium group of TFPB-TgCl and the carboxyl group of NPX, with subsequent electrostatic potential (ESP) analysis emphasizing their crucial role in electrostatic adsorption. Overall, the adsorption mechanism of electrostatic and π-π interactions in TFPB-TgCl highlights the significant contribution of its guanidinium and aromatic rings in facilitating NPX adsorption.

Cyclic voltammetry analysis of mercuric chloride redox reactions with orange G dye

This study investigates the redox behavior of bulk and nano mercuric chloride (HgCl2) using cyclic voltammetry in the presence and absence of Orange G dye, employing 0.1 M KCl as the supporting electrolyte at room temperature. The effects of varying scan rates on electrode processes and redox reaction kinetics were analyzed, revealing that the choice of electrode material, specifically a glassy carbon electrode, significantly influences reproducibility and sensitivity. The study has implications for various applications, including environmental and analytical chemistry. The interaction between mercuric chloride and Orange G was characterized through specific scan rates, highlighting distinct redox peaks and current changes. This research underscores cyclic voltammetry as a powerful technique for probing redox reactions, electroactive species, and complexation processes. Additionally, the determination of complexation stability constants and Gibbs free energies provides valuable insights into the nature of these interactions, paving the way for future applications in environmental and analytical chemistry.Environmental Implication: The redox behaviour of hazardous substance mercuric chloride in the presence of orange G dye has been studied, and the results have important environmental implications. By studying the electrode processes and redox reaction kinetics using cyclic voltammetry, researchers can gain a better understanding of how mercuric chloride behaves in different environmental conditions.The environmental implications of this research are significant. Understanding how mercuric chloride interacts with organic dyes can inform strategies to mitigate mercury pollution, a pressing issue in environmental chemistry. The findings contribute to the broader goal of developing effective remediation strategies for contaminated ecosystems.

Electronic Metal‐Support Interaction Induces Hydrogen Spillover and Platinum Utilization in Hydrogen Evolution Reaction

The substantial promotion of hydrogen evolution reaction (HER) catalytic performance relies on the breakup of the Sabatier principle, which can be achieved by the alternation of the support and electronic metal support interaction (EMSI) is noticed. Due to the utilization of tungsten disulfides as support for platinum (Pt@WS2), surprisingly, Pt@WS2 demands only 31 mV overpotential to attain 10 mA cm‐2 in acidic HER test, corresponding to a 2.5‐fold higher mass activity than benchmarked Pt/C. The pH dependent electrochemical measurements associated with H2‐TPD and in‐situ Raman spectroscopy indicate a hydrogen spillover involved HER mechanism is confirmed. The WS2 support triggers a higher hydrogen binding strength for Pt leading to the increment in hydrogen concentration at Pt sites proved by upshifted d band center as well as lower Gibbs free energy of hydrogen, favourable for hydrogen spillover. Besides, the WS2 shows a comparably lower effect on Gibbs free energy for different Pt layers (‐0.50 eV layer‐1) than carbon black (‐0.88 eV layer‐1) contributing to a better Pt utilization. Also, the theoretical calculation suggests the hydrogen spillover occurs on the 3rd Pt layer in Pt@WS2; moreover, the energy barrier is lowered with increment in hydrogen coverage on Pt.

Hemoglobin targeting potential of aminocarb pesticide: Investigation into dynamics, conformational stability, and energetics in solvent environment

Aminocarb (AMC), a carbamate pesticide, due to its prevalent usage exhibits increased accumulation in the environment affecting both insects and humans. It enters the human body via food grains and be transported through bloodstream. AMC's chemical structure, containing specific molecular frameworks and functional groups, enables it to bind with proteins like albumin and hemoglobin. Given that molecules with similar architecture are known to bind with hemoglobin, we aimed to explore Aminocarb's binding capability and the potential mechanism or mode of its interaction with hemoglobin. Hb being a tetramer with a profound interface between amino acid chains offers multiple binding sites. It is therefore important to investigate the structural aspects of binding of AMC by employing various spectroscopic and in-silico methods. The surface of the α1 chain near the α1β2 interface emerges as the preferred binding site for AMC, primarily due to its conformational restrictions. In its bound state, AMC tends to maintain a relaxed conformation, closely resembling its globally optimized geometry, and resides in close proximity to the α1 chain via multiple hydrophobic contacts and water bridge as observed in molecular dynamics (MD) simulations. Fluorescence quenching experiments showed moderate binding strength (7.7 × 10⁴ L M⁻1 at 288 K, 7.8 × 10⁴ L M⁻1 at 298 K, 7.9 × 10⁴ L M⁻1 at 308 K) and spontaneous binding, driven by hydrophobic and van der Waals interactions, as indicated by enthalpy (0.80–0.91 kJ mol⁻1), entropy (0.0970–0.0974 kJ mol⁻1), and Gibbs free energy (−27.13 to - 29.08 kJ mol⁻1). Circular dichroism experiments reveal no major structural changes in Hb. Quantum chemical calculations and MD simulations reveal conformation-dependent energy differences, enhancing our understanding of AMC's binding mechanism to Hb.

Environmentally friendly production of petroleum systems with high CO2 content

Natural gas hydrates represents a huge source of energy. At the same time substantial leakages of natural gas from hydrates contributes significantly to climate changes. One of the most important reasons for these natural gas fluxes is leakage of seawater in to the hydrates from seafloor, through fracture systems. Hydrate dissociates if surrounding seawater is less than hydrate stability limit. Another interesting aspect of natural gas hydrates is the potential for safe CO2 storage. These different aspects of hydrates in natural sediments put demands on thermodynamic models. In addition to accurate description of pressure temperature hydrate stability there also a need to describe hydrate dissociation in concentration gradients towards surrounding water or surrounding gas as two examples. In this work we present new experimental data and an extensive thermodynamic model for hydrate. In contrast to conventional thermodynamic models for hydrate the model is consistent since all thermodynamic properties are derived from the Gibbs free energy. In this work we examine mixtures of CH4, C2H6, N2, CO2 from the China Sea and some synthetic mixtures, using this model. Maximum CO2 content in these mixtures are 60 mol% and the rest is dominated by CH4. Agreement between experimental data and model calculations are generally good and average deviations are below 5.5% for all the systems and conditions examined. Another aspect of the model is the ability for incorporation of effects of mineral surfaces. Specifically it is illustrated that adsorption of water on rust dominates liquid water drop out from gas as compared to water dew-point. Production of natural gas with such high CO2 content requires a strategy for CO2 separation and storage. It is proposed that the CH4 is separated from the C2H6, CO2 and N2 and cracked to H2 and CO2 using steam. Thermodynamic analysis indicates a significant potential for safe CO2 storage in natural gas hydrate and H2 as the only export product.

Electronic Metal-Support Interaction Induces Hydrogen Spillover and Platinum Utilization in Hydrogen Evolution Reaction.

The substantial promotion of hydrogen evolution reaction (HER) catalytic performance relies on the breakup of the Sabatier principle, which can be achieved by the alternation of the support and electronic metal support interaction (EMSI) is noticed. Due to the utilization of tungsten disulfides as support for platinum (Pt@WS2), surprisingly, Pt@WS2 demands only 31 mV overpotential to attain 10 mA cm-2 in acidic HER test, corresponding to a 2.5-fold higher mass activity than benchmarked Pt/C. The pH dependent electrochemical measurements associated with H2-TPD and in-situ Raman spectroscopy indicate a hydrogen spillover involved HER mechanism is confirmed. The WS2 support triggers a higher hydrogen binding strength for Pt leading to the increment in hydrogen concentration at Pt sites proved by upshifted d band center as well as lower Gibbs free energy of hydrogen, favourable for hydrogen spillover. Besides, the WS2 shows a comparably lower effect on Gibbs free energy for different Pt layers (-0.50 eV layer-1) than carbon black (-0.88 eV layer-1) contributing to a better Pt utilization. Also, the theoretical calculation suggests the hydrogen spillover occurs on the 3rd Pt layer in Pt@WS2; moreover, the energy barrier is lowered with increment in hydrogen coverage on Pt.

Enhanced adsorption-photodegradation of tetracycline using Ce-N-co-doped AC/TiO2 photocatalyst: isotherms, kinetics, mechanism, and thermodynamic insight.

Excessive use of tetracycline (TC) is alarming owing to its increased detection in water systems. In this study, a photocatalyst was developed to degrade TC using a Ce-N-co-doped AC/TiO2 photocatalyst, denoted as Ce/N-AC/TiO2, prepared using the sol-gel method assisted by microwave radiation, speeding up the synthesis process. Ce/N-AC/TiO2 achieved maximum TC degradation of 93.1% under UV light with optimum sorption system conditions of an initial concentration of 10 mg L-1, pH 7, and 30 ℃, under 120 min. Scavenger experiments revealed that holes and superoxide radicals were the active species influencing the photodegradation process.The TC degradation was appropriately fitted with Langmuir isotherms and a pseudo-second-order (PSO) kinetic model. The change in enthalpy (ΔH) (2.43kJmol-1), entropy (ΔS) (0.024kJmol-1), and Gibbs free energy (ΔG) (- 4.941 to - 5.802kJmol-1) suggested that the adsorption process was spontaneous, favourable, and endothermic. Electrostatic interaction, hydrogen bonding, pore-filling, cationic-π, n-π, and π-π interaction were among the interactions involved between TC and Ce/N-AC/TiO2. Furthermore, Ce/N-AC/TiO2 stability was confirmed through 80% removal efficiency even after the fifth reuse cycle. Notably, this work provides new insight into the production of efficient, reusable, and enhanced photocatalysts using a rapid and cost-effective microwave-assisted synthesis process for pollutant remediation.