Catalytic Effect Research Articles

A sustainable and Integrated Microbial Biocatalysis of Resveratrol from Polygonum cuspidatum Siebold & Zucc Using Cellulose-Based Immobilised Aspergillus niger with Deep Eutectic Solvent-Assisted Microreactors.

An efficient and green method was developed using deep eutectic solvent assistance to enhance the biotransformation method of producing resveratrol from Polygonum cuspidatum Siebold & Zucc, using cellulose-based immobilised Aspergillus niger in the process. Various deep eutectic solvents (DES) were screened to obtain a superior biocatalytic effect. The increase in DES concentration aggravated the degree of cell membrane damage. Natural deep eutectic solvents (NADES) exhibited a more favourable catalytic effect than DES due to their excellent biocompatibility. This enhancement is associated with the hydrogen bonding donor components present in NADES, with catalytic ability ranking as alcohol-based > sugar-based > organic acid. CHCL/EG exhibited the maximum catalytic effect at 1.0 wt%. Under optimal conditions (pH 6.5; temperature, 29.5°C; ratio of liquid to solid 20:1 (mL/g), and time 47h), the resveratrol yield reached 32.79mg/g, which was 13.06-fold to that of the untreated sample (2.51mg/g). The residual activity of the cellulose-based microreactor was 81.46% after ten trials. The proposed method was successfully employed, demonstrating higher biocatalysis efficiencies and superior environmental protection compared to conventional solvents for resveratrol biocatalysis.

Mechanistic insights into the use of flotation tail coal for enhanced water electrolysis in hydrogen production

Coal-assisted water electrolysis for hydrogen production (CAWE) is a promising method for the efficient utilization of coal resources and the sustainable generation of hydrogen. However, identifying a cost-effective and efficient carbon source remains a critical and ongoing challenge. This study proposes the use of flotation tail coal as a novel and efficient carbon source for water electrolysis. Through a combination of electrochemical experiments, thermodynamic analysis, and comprehensive material characterization techniques, this research explores the effectiveness of tail coal-assisted water electrolysis for hydrogen production (TCAWE) in enhancing hydrogen production efficiency. It is found that the catalytic effect of minerals, particularly iron and manganese ions, is instrumental in significantly reducing energy consumption and enhancing the anodic oxidation reactions in the CAWE process. Flotation tail coal, with its high content of these catalytic minerals and favorable hydrophilic surface properties, not only lowers the electrolysis voltage but also increases the hydrogen yield compared to traditional coal sources. This research innovatively demonstrates that utilizing flotation tail coal in water electrolysis offers a dual benefit: it provides a cost-effective, abundant carbon source while promoting a more efficient and sustainable hydrogen production process. Additionally, this approach is expected to facilitate the resource utilization of waste flotation tail coal.

Perovskiet-like BaZrO3 nanocatalyst with rich oxygen vacancies on boosting hydrogen storage property of MgH2

Magnesium hydride (MgH2) as a promising solid hydrogen syorage material has been extensively researched. but the higher separating temperature and sluggish kinetics hinder its large-scale practical application. To solve this problem, a BaZrO3 nanocatalyst with abundant oxygen vancies is manuscripted, exerts significant improvement to the hydrogen storage performance of MgH2. Impressively, the onset dehydrogenation temperature of MgH2-10 wt% BaZrO3-Ov composite is reduced markedly from 390 °C(for pure MgH2) to 260 °C. Additionally, the composite can discharge 4.22 wt% H2 with 10 min at 275 °C and a total dehydrogenation amouut of 5.88 wt% is achieved at 300 °C. For hydrogen absorption, the composite can rapidly recharge hydrogen at a low temperature of 150 °C and approximately 5.08 wt% H2 can be absorbed at 275 °C within 10 min. The dehydrogenation activation energy of BaZrO3-Ov-added MgH2 is as low as 92.61 kJ mol−1 compared to pure MgH2 (164.78 kJ mol−1). Meantime, the composite presents unexceptionable reversible kinetic performance with a retention rate of 97.35 % after 10 cycles. The excellent catalytic effects can be attributed to the in-situ generation of ZrO2-Ov, BaO-Ov and ZrH2 from BaZrO3-Ov during the first de-/rehydrogenation cycle, which function as nanosized active sites on MgH2 matrix to accelerate electron transfer and provide abundant hydrogen diffusion channels. Density functional theory calculations results verify that the Mg–H length and dehydrogenation energy barrier are ameliorated through BaZrO3-Ov. This work provides a unique perspective on modification MgH2 by perovskiet-like BaZrO3-Ov nanocatalyst.

Fluorinated‐polyhedral oligomeric silsesquioxane (F‐POSS) functionalized sepiolite nanostructures for developing epoxy nanocomposites with tailored crosslinking, antifouling, and self‐cleaning properties

AbstractDeveloping multifunctional epoxy composites with tailored properties supports energy systems, especially oil and gas industries. We report synthesis of 3D fluorinated‐polyhedral oligomeric silsesquioxanes (F‐POSS) nanoparticles (NPs) co‐condensed on the surface of 2D sepiolite (SEP) nanoclays, and dispersed it within an epoxy resin to facilitate curing kinetics of epoxy‐amine system. A catalytic effect was realized, supporting excellent cure index, according to the kinetic models employed. Friedman model suggested double values of activation energy for composites (54.32 KJ/mol for Epoxy/SEP and 50.73 KJ/mol for Epoxy/F‐POSS@SEP) compared to blank (reference) resin (26.12 KJ/mol). Nanostructure of F‐POSS@SEP observed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM), and Fourier‐transform infrared (FTIR) spectroscopy, demonstrating co‐condensation of F‐POSS and SEP nanoclays. Nanotribology tests suggested higher surface properties. Hardness of epoxy was 0.373 GPa; when modified with 5 and 10 wt% of F‐POSS@SEP it resulted in 0.41 and 0.38 GPa, respectively. The reduced modulus was 4.53 GPa for epoxy, while 5.1 and 5.0 GPa for 5 and 10 wt% F‐POSS@SEP, respectively. The free surface of composites was studied by SEM and contact angle techniques. F‐POSS/SEP nanostructure populated at air‐free surface, as a consequence of natural migration of fluorine. Contact angle measurements were performed in dynamic tests, showing increased hydrophobicity of thermoset composites, where an outstanding antifouling behavior was correspondingly achieved. Sliding angles diminished from 19.1° for epoxy to 8.1° and 5.0° for 5 and 10 wt.% of F‐POSS@SEP, respectively. Accordingly, fouling of 5 and 10 wt.% F‐POSS@SEP modified composites was 42% lower than that for epoxy. Self‐cleaning resulted 18% and 16% higher for 5 and 10 wt.% F‐POSS@SEP nanocomposites, respectively, compared to epoxy. These results are promising to contribute high‐performance materials for the energy production sector.Highlights Developed fluorinated polyhedral oligomeric silsesquioxanes (F‐POSS)/sepiolite. Detected catalytic effect of F‐POSS/sepiolite on epoxy‐amine cross‐linking kinetics. Fouling decreased by 42%, whereas recovery increased 10‐fold by cleaning surface. Self‐cleaning properties demonstrated by up to 74% reduction in water slip angle. Potential use in pipelines to prevent paraffin deposits due to antifouling properties.

Ni/Fe Fluorides (Hydroxide) Nanocomposite as Efficient OER Catalyst.

The synthesis of efficient oxygen evolution reaction (OER) catalysts that markedly reduce the overpotential over an extended period is crucial for electrolytic water splitting toward hydrogen production. A kind of Ni/Fe fluoride (hydroxide) nanocomposite OER catalyst is designed and prepared by a two-step method for the first time. The nanocomposite with the optimal OER performance (Ni:Fe precursor ratio of 9:1) is observed to possess a nanoparticle morphology with size of about 100 nm. Each nanoparticle hosts extensive nanoregions of Ni4OHF7, NiFeF5∙2H2O and Fe1.9F4.75∙0.95H2O phases. The optimal nanocomposite (Ni:Fe precursor ratio of 9:1) exhibits OER overpotential of merely 208 mV and 349 mV at 10 mA cm-2 and 100 mA cm-2 respectively, tafel slope of 53.1, and outstanding stability for 10 h duration at 100 mA cm-2. The superior OER catalytic performance of the optimal nanocomposite after CV activation is mainly ascribed to the comprehensive catalytic effect of multiple Ni, Fe active sites from three phases, the smaller charge transfer resistance achieved at this particular Ni:Fe precursor ratio. The abundant resources of Ni, Fe, F elements and the superior OER properties of the Ni/Fe fluorides (hydroxide) nanocomposite, makes it a good OER catalyst candidate for electrolytic water splitting toward hydrogen production.

Key Metabolites Influencing Astringency and Bitterness in Yinghong 9 Large-Leaf Dark Tea Before and After Pile-Fermentation.

Understanding the impacts of pile-fermentation on the taste quality of dark tea (DT) is crucial. Although the large-leaf DT, Yinghong 9 DT, was successfully developed, its taste quality was not systematically studied. This research aims to analyze how pile-fermentation affects taste. Our taste evaluations indicated that pile-fermentation reduces astringency while slightly increasing bitterness. Through untargeted metabolomic analysis, we identified 16 key metabolites associated with these taste changes. The analysis of the dose-overthreshold values affirmed that rutin, isoquercetin, myricetin 3-galactoside, EGCG, DL-C, and ECG were found to lower astringency, while caffeine contributed to the slight increase in bitterness. Additionally, the changes in these metabolites are closely linked to the catalytic effects of microbial extracellular enzymes. These findings provide a theoretical foundation for a deeper understanding of how pile fermentation influences the taste quality of large-leaf DT.

Integration of MOF/COF core-shell composite material with wrinkled supramolecular hydrogel: A portable electrochemical sensing platform for noradrenaline bitartrate detection

Predictably integration of rigid powder nanocrystals with flexible soft materials for rapid, accurate and portable detection of biological small molecules is an ongoing goal of researchers. In this research, the MOF/COF core-shell composite material (MIL-88B(FeCu)/COF) was constructed via monomer-mediated solvothermal approach. Subsequently, the MIL-88B(FeCu)/COF was effectively combined with chitosan-acrylamide based wrinkled supramolecular hydrogel to form a unique rigid-flexible composite material (MIL(FeCu)/COF@Hy). Next, the noradrenaline bitartrate (NB) was selected as a target molecule for electrochemical behavioral assessment. Of note, the portable electrochemical sensing platform constructed in this study does not require the use of solutions (chitosan or Nafion) to seal the electrode materials, and the portable device provides sufficient convenience for NB detection. And the excellent linear window (0.06–10 and 10–1600 μmol/L), sensitivity (0.0645 and 0.0729 μA μM cm−2), detection limit (0.02 μmol/L) and anti-interference stability can be achieved. The outstanding electrochemical behaviors may be ascribed to: 1) hydrogel matrix significantly improves the dispersion of MOF/COF composite materials and avoids its agglomeration; 2) there are abundant diffusion paths in the hydrogel nanocomposite; 3) the synergistic catalytic effect of MOF/COF and hydrogel. In short, the combination of this heterostructured MOF/COF composite materials and hydrogel soft materials will provide a valuable reference for the rapid detection of biomolecules.

Understanding the Directed Evolution of a Natural-like Efficient Artificial Metalloenzyme.

The artificial metalloenzyme containing iridium in place of iron along with four directed evolution mutations C317G, T213G, L69V, and V254L in a natural cytochrome P450 presents an important milestone in merging the extraordinary efficiency of biocatalysts with the versatility of small molecule chemical catalysts in catalyzing a new-to-nature carbene insertion reaction. This is a show-stopper enzyme, as it exhibits a catalytic efficiency similar to that of natural enzymes. Despite this remarkable discovery, there is no mechanistic and structural understanding as to why it displays extraordinary efficiency after the incorporation of the four active site mutations by directed evolution methods, which so far has been intractable to any experimental methods. In this study, we have deciphered how directed evolution mutations gradually alter the protein conformational ensemble to populate a catalytically active conformation to boost a multistep catalysis in a natural-like artificial metalloenzyme using large-scale molecular dynamics simulations, rigorous quantum chemical (QM), and multiscale quantum chemical/molecular mechanics (QM/MM) calculations. It reveals how evolution precisely positions the cofactor-substrate in an unusual but effective orientation within a reshaped active site in the catalytically active conformation stabilized by C-H···π interactions from more ordered mutated L69V and V254L residues to achieve preferential transition state stabilization compared to the ground state. This work essentially tracks down in atomistic detail the shift in the conformational ensemble of the highly active conformation from the less efficient single mutant to the most efficient quadruple mutant and offers valuable insights for designing better enzymes. The active conformation correctly reproduces the experimental barrier height and also accounts for the catalytic effect, which is in good agreement with experimental observations. Moreover, this conformation features an unusual bonding interaction in a metal-carbene species that preferentially stabilizes the rate-determining formation of an iridium porphyrin carbene intermediate to render the observed high catalytic rate acceleration. Our study provides crucial insights into the underlying rationale for directed evolution, reports the major catalytic role of nonelectrostatic interactions in enzyme catalysis different from the electrostatic model, and suggests a crucial principle toward designing enzymes with natural efficiency.

Crystal defects Boost cellulose conversion to C2 alcohols over Pd/WO3 catalysts

Converting cellulose into C2 alcohols presents a sustainable alternative to fossil fuels, contributing to the development of eco-friendly and economically viable biofuels and chemicals. Tungsten oxide (WO3) is a key solid acid catalyst for this process, yet limited research explores its diverse morphologies and unique catalytic effects. This study investigates diverse WO3 morphologies (nanosheets, nanoflowers, nanoblocks, and tetrahedral octahedra) in combination with Pd for converting cellulose to C2 alcohols. Optimized conditions with Pd/o-WO3 catalyst resulted in the highest C2 alcohols (ethylene glycol and ethanol, 80.9 %), notably yielding 64.8 % ethylene glycol. Extensive characterizations and DFT calculations reveal the smaller element occupancy rates and a longer W-O bond length led to a large number of crystal defects over Pd/o-WO3. It facilitated the formation of W5+–OH sites and Pd-O(H)-W interactions, further synergistically enhancing hydrogenation ability and acidity. Designed experiments to elucidate cellulose conversion pathways, including hydrolysis, retro-aldol condensation, and hydrogenation. This study emphasizes the unique impact of WO3 morphologies and underscores the importance of supporting crystal defects for catalytic performance in eco-friendly biofuel and chemical production.

Slow release performance of the immobilized carbon dots and their enhancing effect on anaerobic denitrification

Carbon dots (CDs) can improve microbial electron transfer rates and denitrification activities via entering the cells. To avoid the frequent addition of CDs in practical application, in this study, CDs were first covalently immobilized on bio-carrier polypropylene nonwoven fabrics. The immobilized CDs (iCDs) could be slowly released and enter the cells, thus enhancing the activities of the denitrifying-related enzymes and electron transfer system of Stutzerimonas stutzeri ATCC 17588, during which the nitrate removal rate was significantly increased by 47.2 % with the reduced accumulation of nitrite and N2O. During the tested 10 cycles, the iCDs exhibited stable accelerating performances on nitrate removal (an average increase of 39.9 %). Proteomics analysis showed that the slow-release performance of iCDs was mainly attributed to the catalytic effect of extracellular amidases and esterases. At the community level, the iCDs addition also resulted in the increase of denitrification rate mediated by the enriched denitrification community containing main genera Stutzerimonas, Thauera and Pannonibacter. Further metagenomics analysis showed that the three genera containing genes encoding amidases and denitrifying-related enzymes could perform denitrification process together via obtaining iCDs. These results indicate that iCDs are of potential application for the treatment of nitrate-containing wastewaters.

A new difunctional nanopolypropylene surface molecularly imprinted polyacrylamide catalytic probe for determination of trace sulfadiazine with resonance Rayleigh scattering technique

A new nanopolypropylene (PP) surface molecularly imprinted polyacrylamide (PP@MIP) probe was synthesized facilely for the Resonance Rayleigh Scattering (RRS) determination of trace sulfadiazine (SDZ), using PP as nanosubstrate, SDZ as template molecule, and the acrylamide as functional monomer. The catalytic effect of PP@MIP on the reduction of HAuCl4 by hydrazine hydrate to form AuNP, a nano-indicated reaction, was investigated. The generated AuNPs had a strong RRS effect, and the addition of SDZ resulted in the selective formation of PP@MIP-SDZ complex, which further promoted the generation of AuNP and increased the RRS signal. Therefore, there was developed a novel RRS assay platform for rapid, selective and sensitive detection of SDZ with a linearity range of 0.0125–0.150 nmol/L and limit of detection of 0.004 nmol/L. The recoveries were in the range of 93.3–109.9 % with the relative standard deviations (RSDs) in the range of 2.55–9.14 % in the real sample analysis.

Preparation, characterization and modification of magnesium hydride for enhanced solid-state hydrogen storage properties

Magnesium–magnesium hydride (Mg–MgH2) system has attracted attention worldwide recently because of its simple hydrogenation-dehydrogenation process, the cost-effectiveness of the raw materials, and relatively high hydrogen storage capacity compared to the other metal-metal hydride systems. The present study deals with the optimization of the process parameters for the synthesis of magnesium hydride (MgH2) in sizable quantities using commercial-grade magnesium powder, characterization with respect to hydrogen storage capacity, by thermal dehydrogenation and pH-controlled aqueous hydrolysis. The thermal hydrogenation-dehydrogenation and mild acidified aqueous dehydrogenation behaviour of MgH2 were studied systematically to compare the decomposition kinetics and storage capacity. The superior catalytic effect of V2O5 on decreasing the onset-dehydrogenation temperature of MgH2 is demonstrated. The MgH2-5 wt. % mesoporous V2O5 sample starts releasing hydrogen at 220 °C, which is substantially less than the as-synthesized un-catalysed MgH2 under identical conditions which starts releasing hydrogen at 430 °C. The dehydrogenated MgH2-5wt. %V2O5 could be completely re-hydrogenated at 150 °C. Hydrolysis of as-synthesized MgH2 was demonstrated using an aqueous solution using tartaric acid and the dehydrogenation behaviour was co-related with the pH of the solution. More than 90% hydrogen yield was achieved by the hydrolysis of MgH2 in a tartaric acid solution of pH-4. Based on the result, a hydrogen gas dispenser using solid-state magnesium hydride as a hydrogen source is proposed for laboratory applications for the supply of ultra-pure hydrogen for various reactions and crystal growth experiments.

Improvement of fame retardancy and thermal stability of epoxy composites by modifying salen-based polyphosphazene microspheres with Co-based metal organic frameworks

A functionalized cross-linked polyphosphazenes microsphere (Salen-PZN-Ni@Co-MOF) was fabricated by enveloping Salen-Ni-based polyphosphazenes (Salen-PZN-Ni) with a type of hybrid flame retardant (Co-MOF) to enhance the flame retardant, smoke suppression properties and mechanical properties of epoxy (EP) composites. Thermogravimetric analysis indicated that the incorporation of Salen-PZN-Ni@Co-MOF significantly enhanced the thermal stability of the EP composites. The existence of Salen-PZN-Ni@Co-MOF enhanced both the vertical burning rating and resulted in a higher limiting oxygen index. The addition of 5 wt% Salen-PZN-Ni@Co-MOF conspicuously improved the fire safety of EP, as evidenced by the results of the cone calorimeter. For instance, the peak heat release rate and total heat release rate of the EP composites were decreased by 25.3% and 44.97%, respectively. In addition, the incorporation of Salen-PZN-Ni@Co-MOF significantly inhibited the generation of toxic carbon monoxide and other volatile compounds. Furthermore, a synergistic effect between Salen-PZN-Ni and Co-MOF was observed. The proposed flame retardant mechanism of Salen-PZN-Ni@Co-MOF is attributed to the synergistic catalytic carbonization effect and the formation of thermally stable components. Consequently, enhanced fire safety in EP composites is achieved through the synergistic interaction among various components (nickel and Co-MOF) with polyphosphazene microspheres. Meanwhile, the excellent compatibility between Salen-PZN-Ni@Co-MOF and EP enhances the mechanical properties of EP composites.

Construction of carbon nanotube-multifunctional porous ionic polymer core–shell nanocomposite for efficient conversion of carbon dioxide under co-catalyst free conditions

Metalated porous ionic polymers featuring multiple active sites show significant potential for carbon dioxide (CO2) fixation. However, general and efficient strategies to enhance their catalytic efficiency still remain to be developed. Herein, carbon nanotube-multifunctional ionic polymer core–shell composite (CNT@P(TBr-Py)-ZnBr2) was easily prepared by a solvothermal radical copolymerization strategy, followed by metallization with ZnBr2. Characterization revealed that the synthesized composite exhibited a distinct core–shell tubular nanostructure, with CNT serving as the core, and multifunctional polymer containing Lewis acid (Zn), nucleophilic Br¯ and CO2-philic triazine groups as the shell. Furthermore, the composite displayed broad pore size distribution and large average pore size. Impressively, CNT@P(TBr-Py)-ZnBr2 delivered an outstanding catalytic efficiency in the cycloaddition of CO2 to epichlorohydrin, surpassing the control catalysts poly(triazine-based vinyl ionic liquid) (PTBr), bipyridine-functionalized porous ionic polymer (P(TBr-Py), and ZnBr2 metalated P(TBr-Py) (P(TBr-Py)-ZnBr2) by factors of 5.4, 5.8, and 1.3, respectively. At 140 °C, a high turnover frequency (TOF) of 11174 h−1 and a 93.4 % yield of target cyclic carbonate were achieved in the absence of any additional co-catalyst. This exceptional catalytic performance of CNT@P(TBr-Py)-ZnBr2 can be mainly attributed to its unique core–shell structure, along with the synergistic catalytic effect of its multifunctional active sites. Also, the reaction can proceed smoothly under near-ambient conditions (30 °C, 1 bar CO2), though a longer reaction time was required. Additionally, CNT@P(TBr-Py)-ZnBr2 demonstrated a wide range of substrate compatibility and excellent recycling stability. This work therefore presents a viable approach for designing efficient and multifunctional ionic polymer-based catalysts for CO2 fixation.

Substitution of the Axial Type 1 Cu Ligand Affords Binding of a Water Molecule in Axial Position Affecting Kinetics, Spectral, and Structural Properties of the Small Laccase Ssl1.

Multicopper oxidases use Cu ions as cofactors to oxidize various substrates. High reduction potential at Type 1 Cu is considered as crucial for effective catalysis. Previous studies have shown that replacing the axial methionine ligand of the Type 1 Cu with leucine or phenylalanine leads to an increased reduction potential, but not always to higher enzyme activity. Here we present a study on six variants of the small laccase Ssl1 from Streptomyces sviceus, where the axial methionine ligand was substituted, and the effect of the axial ligand on reduction potential, activity, spectral properties and structure was investigated. Absorption, electronic circular dichroism and EPR spectra revealed the presence of a stronger coordinating axial ligand like oxygen, which influences the electronic and catalytic properties more than the nature of the amino acid side chain. The crystal structures of the Ssl1 variants were solved, which show that none of the amino acid side chains coordinate to the Cu. Instead, a water molecule is found in the axial coordination site, which support the spectroscopic data. Our findings highlight the importance of combining structural and spectroscopic methods to investigate the effect of amino acid exchange on multicopper oxidases.

Subtle Tuning of Catalytic Well Effect in Phthalocyanine Covalent Organic Frameworks for Selective CO2 Electroreduction into C2H4.

In the electrocatalytic CO2 reduction reaction (CO2RR), the strategic design of a catalytic well capable of regulating the overall confinement effects of catalytic sites holds significant promise for enhancing multiple-electron transfer and C─C coupling efficiency, particularly for the generation of C2+ products. Here, a series of Cu-salphen-based covalent organic frameworks (COFs) featuring hydroxyl-induced catalytic well are synthesized, which demonstrate successful application in electrocatalytic CO2RR to yield multiple-electron transferred products. The meticulously engineered catalytic well, facilitated by multi-hydroxyl groups, manifests robust confinement effects, facilitating selective adsorption, enrichment, and activation of CO2, intermediate stabilization, and reduction of energy barriers for electrocatalytic CO2RR. Specifically, product selectivity can be finely tuned from CH4 to C2H4 by modulating the levels of catalytic well, with CuPc-DFP-4OH-Cu exhibiting the most pronounced catalytic well effect, yielding a high 56.86% faradaic efficiency (FE) for C2H4 at -0.7 V, while CuPc-DFP-Cu, with the weakest catalytic well effect, achieves a 75.24% FE for CH4 at -1.0 V. Notably, the attained FE for C2H4 (56.86%) surpasses that of all reported COFs to date. Complemented by theoretical calculations and in situ tests, this study delves deeply into the pivotal roles of hydroxyl-induced catalytic well with confinement effects.

Understanding Ion-Specific "Hofmeister" Effects in Enzyme Catalysis Through Using RNase A as a Paradigm Model.

Biophysical studies in the last two decadesdemonstratethat salts affect biomolecules in an ion-specific manner. Diverse biological processes such as protein folding, protein precipitation, protein coacervation and phase separation, and protein oligomerization,all showthat this ion specificity directly relatesto how individual ions interact with biomolecular surfaces. Interestingly, although ion-specific effects upon enzyme catalytic processes are well-known in the literature, a molecular level description of these effects is not yet available. This workaddresses this need by investigating ion-specific effects upon the enzymatic activity and stability of RNase A. We have developed a robust framework to analyze and quantify ion-specific effects upon the RNase A catalyzed phosphate ring opening reaction of cCMP.Both the folding thermodynamics and the Michaelis-Menten kinetic parameters of this enzyme show ion-specificity. However, these effects are not necessarily directly related to each other. Ion-specific effects observed in protein folding reflects mostly how an individual ion interacts with the overall protein surface; while alternatively, ion-specific effects on enzyme activity indicate how a given ion interacts with the enzyme active site surface or alternatively, how ions interact with the substrate molecule as represented by changes in the substrate thermodynamic activity coefficient.

MOF incorporated Polyethersulfone/Polylactic Acid ultrafiltration membranes for the catalytic removal of dyes via persulfate activation

This study synthesized novel nanocellulose/zeolitic Imidazolate Framework nanocomposite blended Polyethersulfone/Polylactic Acid (PES/PLA-CNF@ZIF-8) membranes through a modified phase inversion process. This is the first time that a nanocellulose-MOF composite catalytic nanomaterial has been synthesized and used as an additive in polymeric membranes. The morphology and chemical structure of the membranes and nanoparticles were characterised by scanning electron microscopy (SEM), atomic force microscopy (AFM) and Fourier transform infrared (FTIR) respectively. Membrane wettability and crystalline structure were characterised by contact angle, and X-ray diffraction (XRD) analysis respectively. CNF@ZIF-8 modified membranes showed improved contact angle which decreased from 76° in the pristine membranes to 40° in 2 wt% membranes, bulk porosity increased from 74.3.3 % to 81.06 % while the pure water flux increased from 208.30 Lm-2h−1 to 348.73 Lm-2h−1. Further, the modified membranes showed an increase in surface roughness reaching 84.14 nm in 2 wt% membranes. The synthesized membranes have been used as catalysts in the activation of persulfate to degrade Rhodamine B dye. The modified membranes displayed a high catalytic effect (>90 %) in activating persulfate to degrade RhB dye when compared to pristine membranes which showed a degradation efficiency of < 35 %. The study found that the optimum parameters for pH, membrane (catalyst) dosage, oxidant and initial dye concentration were 5, 0.3 g, 0.4 mM and 10 ppm respectively. Quenching experiments showed that •SO4- and •OH radicals were responsible for the dye degradation, with •SO4- radicals playing a major role in the oxidative degradation of the RhB dye. The synthesized membranes showed good stability when tested within five cycles, with the membranes showing degradation efficiency ranging from 92.1 % in the 1st cycle to 91.9 % in the 3rd cycle, before decreasing to 75.3 % in the 5th cycle. This study has therefore shown that the synthesized PES/PLA-CNF@ZIF-8 membranes have potential for use as catalysts in the degradation of cationic dyes in wastewater treatment through persulfate activation.

Single Atomic Cu-C3 Sites Catalyzed Interfacial Chemistry in Bi@C for Ultra-Stable and Ultrafast Sodium-Ion Batteries.

Regulating interfacial chemistry at electrode-electrolyte interface by designing catalytic electrode material is crucial and challenging for optimizing battery performance. Herein, a novel single atom Cu regulated Bi@C with Cu-C3 site (Bi@SA Cu-C) have been designed via the simple pyrolysis of metal-organic framework. Experimental investigations and theoretical calculations indicate the Cu-C3 sites accelerate the dissociation of P-F and C-O bonds in NaPF6-ether-based electrolyte and catalyze the formation of inorganic-rich and powerful solid electrolyte interphase. In addition, the Cu-C3 sites with delocalized electron around Cu trigger an uneven charge distribution and induce an in-plane local electric field, which facilitates the adsorption of Na+ and reduces the Na+ migration energy barrier. Consequently, the obtained Bi@SA Cu-C achieves a state-of-the-art reversible capacity, ultrahigh rate capability, and long-term cycling durability. The as-constructed full cell delivers a high capacity of 351 mAh g-1 corresponding to an energy density of 265 Wh kg-1. This work provides a new strategy to realize high-efficient sodium ion storage for alloy-based anode through constructing single-atom modulator integrated catalysis and promotion effect into one entity.

Synergistic Effect of TiO₂ Nanorods Incorporated with Graphene Oxide for Photocatalytic Degradation of Multiple Dyes

The treatment of dye-contaminated wastewater is essential for mitigating environmental and health risks. In this study, we developed a novel nanocomposite, TiO₂-incorporated graphene oxide (TiO₂@GOn), aimed at enhancing the photocatalytic degradation of neutral red dye, which served as the target analyte. The photocatalysis technique was employed, leveraging the excitation of TiO₂ under UV light to generate reactive oxygen species for efficient dye degradation. TiO₂ nanorods were combined with graphene oxide to form the TiO₂@GOn nanocomposite, designed to improve charge separation and enhance catalytic activity. Nanocomposite characterization was carried out using X-ray diffraction (XRD) to determine crystallographic structure, scanning electron microscopy (SEM) to visualize surface morphology, and UV–Vis spectroscopy to evaluate the optical properties and photocatalytic behavior. The TiO₂@GOn nanocomposite demonstrated a synergistic catalytic effect, outperforming pristine TiO₂ and graphene oxide individually in dye degradation. This study introduces a highly efficient nanomaterial for environmental applications, offering a sustainable approach to the treatment of dye pollutants in wastewater.