Range Of pHs Research Articles

PH Dependence of Amyloid-β Fibril Assembly Kinetics: Unravelling the Microscopic Molecular Processes.

Central to Alzheimer's disease (AD) is the assembly of the amyloid-beta peptide (Aβ) into fibrils. A reduction in pH accompanying inflammation or subcellular compartments, may accelerate fibril formation as the pH approaches Aβ's isoelectric point (pI). Using global fitting of fibril formation kinetics over a range of pHs, we identify the impact net charge has on individual fibril assembly microscopic rate constants. We show that the primary nucleation has a strong pH dependence. The titration behaviour exhibits a mid-point or pK a of 7.0, close to the pK a of Aβ histidine imidazoles. Surprisingly, both the secondary nucleation and elongation rate constants are pH independent. This indicates the charge of Aβ, in particular histidine protonation, has little impact on this stage of Aβ assembly. These fundamental processes are key to understanding the forces that drive the assembly of Aβ into toxic oligomers and fibrils.

PH Dependence of Amyloid-β Fibril Assembly Kinetics: Unravelling the Microscopic Molecular Processes.

Central to Alzheimer's disease (AD) is the assembly of the amyloid-beta peptide (Aβ) into fibrils. A reduction in pH accompanying inflammation or subcellular compartments, may accelerate fibril formation as the pH approaches Aβ's isoelectric point (pI). Using global fitting of fibril formation kinetics over a range of pHs, we identify the impact net charge has on individual fibril assembly microscopic rate constants. We show that the primary nucleation has a strong pH dependence. The titration behaviour exhibits a mid-point or pKa of 7.0, close to the pKa of Aβ histidine imidazoles. Surprisingly, both the secondary nucleation and elongation rate constants are pH independent. This indicates the charge of Aβ, in particular histidine protonation, has little impact on this stage of Aβ assembly. These fundamental processes are key to understanding the forces that drive the assembly of Aβ into toxic oligomers and fibrils.

Immobilization of the Bacillus licheniformis α-Amylase on Azole Functionalized Nanoparticle: More Active, Stable, and Usability.

Enzymes are a powerful tool employed in industrial applications due to their high specificity and efficiency. Amylase enzymes play an important role in detergent, textile, analytical chemistry, and paper industries. Here we present the design, synthesis, and characterization of azole functionalized nanoparticles for the immobilization of α-amylase from Bacillus licheniformis (BlA). A modest binding efficiency (47%) was determined by the BCA assay. Enzymatic activity was measured using DNS method and illustrated the immobilization of amylase with the designed nanoparticles enhanced the thermal stability and long-term storage of amylases at a wide range of temperatures and pHs. With the required scale-up study, these implications amplify novel ways to implement this Fe3O4-PGMA-5A immobilized BlA enzyme in particular industrial applications.

Characterization of Carboxylic Acid Reductase from Mycobacterium phlei Immobilized onto Seplite LX120.

A multi-domain oxidoreductase, carboxylic acid reductase (CAR), can catalyze the one-step reduction of carboxylic acid to aldehyde. This study aimed to immobilize bacterial CAR from a moderate thermophile Mycobacterium phlei (MpCAR). It was the first work reported on immobilizing bacterial CAR onto a polymeric support, Seplite LX120, via simple adsorption. Immobilization time and protein load were optimized for MpCAR immobilization. The immobilized MpCAR showed optimal activity at 60 °C and pH 9. It was stable over a wide range of temperatures (10 to 100 °C) and pHs (4–11), retaining more than 50% of its activity. The immobilized MpCAR also showed stability in polar solvents. The adsorption of MpCAR onto the support was confirmed by Scanning Electron Microscopy (SEM), Fourier-Transform Infrared (FTIR) spectroscopy, and Brunauer–Emmett–Teller (BET) analysis. The immobilized MpCAR could be stored for up to 6 weeks at 4 °C and 3 weeks at 25 °C. Immobilized MpCAR showed great operational stability, as 59.68% of its activity was preserved after 10 assay cycles. The immobilized MpCAR could also convert approximately 2.6 mM of benzoic acid to benzaldehyde at 60 °C. The successfully immobilized MpCAR on Seplite LX120 exhibited improved properties that benefit green industrial processes.

Experimental Clarification of PRPS-1 Structural Essentials.

Phosphoribosyl pyrophosphate synthetase-1 (PRPS-1; EC 2.7.6.1.) catalyzes the binding of phosphate-group to ribose 5-phosphate, forming the 5-phosphoribosyl-1-pyrophosphate, which is necessary for the salvage pathways of purine and pyrimidine, pyridine nucleotide cofactors - NAD and NADP, the amino acids histidine and tryptophan biosynthesis. We aimed to investigate the impact of the different effectors on the activity of PRPS-1, to check the activity of the enzyme in vitro in a wide range of pHs and investigate some structural essentials of the enzyme, isolated from brain and liver. Molecular docking analyses were used to delineate the essentials of PRPS-1 structure, to find out the existence of enzyme effectors. Previously created by us kit was used for determination of the activity of PRPS-1 based on the formation of the inorganic phosphates (λ = 700 nm, Cary 60, Agilent, USA). Effectors impact on the activity of PRPS-1 was evaluated. In silico results of the effectors were later proven by in vitro experiments. For the first time biochemical essentials, including the existence of the multiple pockets, involvement of the amino acids into the processes of interactions with the effectors, evolutional of the sequence conservation, tissue depended Vmax differences were identified.

Characterization and complete genome analysis of a bacteriophage vB_EcoM_DE7 infecting donkey-derived Escherichia coli

A lytic bacteriophage vB_EcoM_DE7 (hereafter designated DE7) that could infect donkey-derived Escherichia coli was isolated. The bacteriophage was examined by transmission electron microscopy, and the result showed that DE7 belonged to the family Myoviridae. The microbiological characterization revealed that DE7 was stable over a broad range of pHs (3 ∼10) at 40-50 °C. The latent period was 10 min, and the burst size was 43 PFUs/infected cell. The whole-genome sequencing showed that DE7 was a dsDNA virus and had a genome of 86,130 bp. The genome contained 124 predicted open reading frames (ORFs), 35 of which had known functions, including DNA replication and modification, transcriptional regulation, structural and packaging proteins, and host cell lysis. Twenty tRNA genes were identified, but no genes associated with bacterial pathogenicity, lysogeny and drug resistance were identified. BLASTN analysis revealed that phage DE7 had a high sequence identity (96%) with Salmonella phage vB_SPuM_SP116, but it could not lyse any Salmonella strain tested in this study. DE7 was classified as a Felix O1-like virus based on its general characterization and genomic information. Since phage DE7 exhibited high efficacy in lysing E. coli and lacked genes associated with bacterial virulence, antimicrobial resistance and lysogeny, it could be potentially used to control foal diarrhoea caused by E. coli.

A highly photostable and versatile two-photon fluorescent probe for the detection of a wide range of intracellular nitric oxide concentrations in macrophages and endothelial cells.

Nitric oxide (NO) is involved in many biological processes affecting the cardiovascular, nervous and immune systems. Intracellular NO can be monitored using fluorescent probes in combination with fluorescence imaging techniques. Most of the currently available NO fluorescent molecular probes are excited via one-photon excitation using UV or Vis light, which results in poor penetration and high photodamage to living tissues. Here, we report a two-photon fluorescent molecular probe, DANPY-NO, able to detect NO in live cells. The probe consists of an o-phenylenediamine linked to a naphthalimide core; and operates via photoinduced electron transfer. DANPY-NO exhibits good sensitivity (LOD of 77.8nM) and high selectivity towards NO, and is stable over a broad range of pHs. The probe targeted acidic organelles within macrophages and endothelial cells, and demonstrated enhanced photostability over a commercially available NO probe. DANPY-NO was used to selectively detect endogenous NO in RAW264.7ϒ NO- macrophages, THP-1 human leukemic cells, primary mouse (bone marrow-derived) macrophages and endothelial cells. The probe was also able to detect exogenous NO in endothelial cells and distinguish between increasing concentrations of NO. The NO detection was evidenced using confocal laser scanning and two-photon microscopies, and flow cytometry. Further evidence was obtained by recording the changes in the intracellular fluorescence emission spectrum of the probe. Importantly, the probe displayed negligible toxicity to the analysed biological samples. The excellent sensitivity, selectivity, stability and versatility of DANPY-NO confirm its potential for in vitro and in vivo imaging of NO.

N → N’ acyl migration in the context of a medicinal chemistry program

A series of tertiary amides was identified as lead matter for a new medicinal chemistry program. Analysis of analogs made for structure activity studies and physicochemical property measurements revealed that some of these tertiary amides were prone to acyl migration. A series of compounds designed to assess the propensity for acyl migration was synthesized. Qualitative time and temperature kinetics were followed up with quantitative kinetic measurements using 1H NMR techniques. Many of the examined tertiary amides from this series were shown to migrate under range of pHs and temperatures. Our finding serves as a cautionary note for others working with amides of a similar nature.

Sensitive and highly selective colorimetric biosensing of vitamin-C and vitamin-B1 by flavoring agent-based silver nanoparticles.

A sensitive scheme was established for the detection of vitamin C (Ascorbic acid) and vitamin B1 (Thiamin HCl) using Maltol capped AgNPs (McAgNPs) as colorimetric sensor. The designed scheme showed an instant alteration in color from yellow to orange and green for vitamin-C and vitamin B1 sequentially. The probe was sensitive in a concentration range of (0-1µM) with limit of detection 0.064 and 0.038µM for vitamin C and vitamin B1 sequentially. The interaction mechanism between vitamin C and vitamin B1 and McAgNPs was evaluated by visible spectroscopy, FTIR, and AFM. Vitamin C attaches on the surface of nanoparticles by C=O group, while OH, C-S-C, and NH2 groups are involved in the binding of vitamin B1 with McAgNPs. The Vit-C/Vit-B1-McAgNPs complexes were stable over a wide range of pHs. The size of McAgNPs increased after the interaction of vitamin C/vitamin B1 from 30-40nm to 500 and 400nm sequentially. The scheme was successfully applied for the detection of vitamin C and vitamin B1 in urine, plasma, water, and commercial pharmaceutical tablets with good recoveries. The scheme was ascertained to be more sensitive than many other formerly described schemes.

Effects of pH and exposure time to alkaline solutions on the mineralogy of the Opalinus Clay from the lower sandy facies of Mont Terri site

The Opalinus Clay is a claystone considered as potential host rock for deep geological disposal of radioactive wastes in Switzerland and Gemany. During the operational phase of the repository, an increase in underground water pH, from 7.5 to a value as high as 13.5 is expected, due to the release of alkaline plumes from concrete degradation, resulting in possible changes in the mineralogy of the host rock. While clay mineral dissolution is known to occur and affect the hydro-mechanical properties of the host rock, the dissolution of other minerals present in claystone, i.e., quartz and calcite, can also take place. This study focuses on identification of such dissolutions by considering NaOH, Ca(OH)2 and KOH alkaline solutions at different pHs (8.5, 11.5 and 13.5). A low pH = 8.5 was investigated to consider the gradual increase in pH of the underground water resulting from the progressive infiltration of alkaline plumes. Series of Opalinus Clay samples from the lower sandy facies of Mont Terri site were immersed in these solutions for six months and for one year. It was found that quartz dissolution occurred significantly at pHs higher than 11.5, but also at pHs as low as 8.5. The longer the exposure time, the more significant the quartz dissolution. Calcite dissolution was observed after six months at pH higher than 11.5, and after one year at pH higher than 8.5. Thus, the quartz dissolution seemed to be governed by the exposure time, while the calcite dissolution seemed to depend on both exposure time and pH value, due to carbonation phenomenon. While generally attention has been paid to the effect of alkalinity on clay minerals, this paper meticulously studies the dissolution of quartz and calcite initially present in significant proportions in the Opalinus Clay from the lower sandy facies of Mont Terri site by investigating a wide range of pHs. The dissolution of such minerals will undoubtedly affect the hydraulic and mechanical properties of the claystone. Thereby, it is of paramount importance to study this phenomenon in order to ensure the long-term safety of the nuclear waste disposal. Furthermore, by investigating a wide range of pHs, attention is paid to both the early stage of site water pH increase (low pHs) and the late stage (high pHs).

Ozone β-Cyclodextrin Inclusion Complex Characterization and Application in the Remediation of Total Petroleum Hydrocarbons

Green remediation is essential in the current practice of water resources management. In this study, a series of ozone β-cyclodextrin (O3-βCD) inclusion complexes were prepared under a selected range of different ozone concentrations, β-CD concentrations, and solution pHs to test their ozone release rates and efficiencies in the treatment of total petroleum hydrocarbons (TPH) in water. The main objectives of this study are to characterize the O3-βCD system, mathematically model its ozone release rate, and test its capability in the degradation of pollutants. From the results, it was found that by defining a set of dimensionless parameters, including β-CD to ozone molar ratio and various degrees of ozone saturation, the steady-state conditions in the O3-βCD system can be represented by a newly developed dimensionless plot. In an optimal condition, the dissolved ozone release rate of 6.8 × 10−5 mM/min can be achieved in the O3-βCD system. A mathematical model was successfully developed to estimate the ozone release rate. In the TPH removal experiments, the effects of β-CD to ozone molar ratio and ozone dosage on the removal efficiency were rigorously examined. Overall, an optimal TPH removal of nearly 90% can be achieved in the treatment of 50 mg/L of TPH in water using this inclusion complex reagent.

Characteristics of immobilized dye-decolorizing peroxidase from Bacillus amyloliquefaciens and application to the bioremediation of dyeing effluent

Dyeing effluent is a major source of aquatic pollution, necessitating novel remediation techniques. In this paper, dopamine-modified, chitosan-coated, halloysite nanotube (HNT) porous microspheres, which are biomimetic entities with a 3D nest-like architecture, were used as a matrix to immobilize dye-decolorizing peroxidase from Bacillus amyloliquefaciens (BaDyP). The porous HNT microspheres showed excellent loading capacity for BaDyP—as high as 250.8 mg/g. Compared with free BaDyP, immobilized BaDyP exhibited better stability over a wide range of pHs and temperatures. At 25 ℃, pH 4.5, and with 2, 2′-azinobis (3-ethylbezthiazoline-6-sulfonate) (ABTS) as an oxidation substrate, the Michaelis constant of immobilized BaDyP was 0.70 mM. The reusability of BaDyP is enhanced by immobilization and approximately 57.6% of the initial activity was retained after six recycling batches. Immobilized BaDyP showed great ability to decolorize various dyes and remediate dyeing effluents. It removed 52.77% of the chemical oxygen demand (COD) and provided 93.93% decolorization (Hazen Units; 89.96% in terms of ADMI), accompanied by significant detoxification within a 72-h incubation period. These results demonstrate the feasibility of using immobilized BaDyP on modified HNTs for the bioremediation of dyeing wastewater. The application of HNT-immobilized BaDyP to the continuous treatment of dyeing effluents in fixed bed reactors will be the next focus of research.

An Unusual Aspartic Acid Cluster in the Reovirus Attachment Fiber σ1 Mediates Stability at Low pH and Preserves Trimeric Organization.

The reovirus attachment protein σ1 mediates cell attachment and receptor binding and is thought to undergo conformational changes during viral disassembly. σ1 is a trimeric filamentous protein with an α-helical coiled-coil tail, a triple-β-spiral body, and a globular head. At the trimer interface, the head domain features an unusual and conserved aspartic acid cluster, which forms the only significant intratrimer interactions in the head and must be protonated to allow trimer formation. To define the role of pH on σ1 stability and conformation, we tested its domains over a wide range of pH values. We show that all domains of σ1 are remarkably thermostable, even at the low pH of the stomach. We determined the optimal pH for stability to be between pHs 5 and 6, a value close to the pH of the endosome and of the jejunum. The σ1 head is stable at acidic and neutral pH but detrimerizes at basic pH. When Asp345 in the aspartic acid cluster is mutated to asparagine (D345N), the σ1 head loses stability at low pH and is more prone to detrimerize. Although the D345N mutation does not affect σ1 binding affinity for the JAM-A receptor, the overall binding stoichiometry is reduced by one-third. The additional replacement of the neighboring His349 with alanine disrupts inner trimer surface interactions, leading to a less thermostable and monomeric σ1 D345N head that fails to bind the JAM-A receptor. When the body is expressed together with the head domain, the thermostability is restored and the stoichiometry of the binding to JAM-A receptor is preserved. Our results confirm a fundamental role of the aspartic acid cluster as a pH-dependent molecular switch controlling trimerization and enhancing thermostability of σ1, which represent essential requirements to accomplish reovirus infection and entry and might be common mechanisms among other enteric viruses. IMPORTANCE Enteric viruses withstand the highly acidic environment of the stomach during transmission, and many of them use low pH as a trigger for conformational changes associated with entry. For many nonenveloped viruses, the structural basis of these effects is not clear. We have investigated the stability of the reovirus attachment protein σ1 over a range of pHs and find it to be remarkably thermostable, especially at low pH. We identify a role for the aspartic acid cluster in maintaining σ1 thermostability, trimeric organization, and binding to JAM-A receptor especially at the gastric pH reovirus has to withstand while passing the stomach. The understanding of monomer-trimer dynamics within σ1 enhances our knowledge of reovirus entry and has implications for stability and transmission of other enteric viruses.

Kinetics and mechanisms of the carbamazepine degradation in aqueous media using novel iodate-assisted photochemical and photocatalytic systems

The present study investigates the kinetics and mechanisms of carbamazepine (CBZ) degradation using a novel UV/iodate (IO3−) system for the first time and explores the influence of process conditions on its degradation. UV/IO3− showed high degradation efficiencies in a wide range of pHs, especially under neutral and acidic conditions, indicating that the system can be considered as a promising method to deal with effluents under various pH conditions. Radical scavenging experiments show that both iodine radicals (IO, IO2 and IO3) and hydroxyl radicals play an important role in CBZ degradation. Furthermore, the combination of UV/IO3− with TiO2 was studied to explore the potential of the addition of IO3− to improve the efficiency of the conventional TiO2 photocatalytic system. Scavenging experiments indicated that iodine radicals (IO, IO2 and IO3) were mainly involved in the degradation of CBZ in the UV/IO3−/TiO2 system, and the reaction mechanism equations were proposed for the first time for the studied UV/IO3−/TiO2 system. Several degradation products and four possible pathways of CBZ degradation were also elucidated using ultra-high-performance liquid chromatography in combination with a quadrupole time-of-flight mass spectrometer (Q-TOF MS). Respirometric tests indicated that the treatment has a positive impact on biomass behavior during subsequent biological purification, highlighting that the developed IO3−-assisted AOPs are eco-friendly.

Modifying the pH sensitivity of OmpG nanopore for improved detection at acidic pH

The outer membrane protein G (OmpG) nanopore is a monomeric β-barrel channel consisting of seven flexible extracellular loops. Its most flexible loop, loop 6, can be used to host high-affinity binding ligands for the capture of protein analytes, which induces characteristic current patterns for protein identification. At acidic pH, the ability of OmpG to detect protein analytes is hampered by its tendency toward the closed state, which renders the nanopore unable to reveal current signal changes induced by bound analytes. In this work, critical residues that control the pH-dependent gating of loop 6 were identified, and an OmpG nanopore that can stay predominantly open at a broad range of pHs was created by mutating these pH-sensitive residues. A short single-stranded DNA was chemically tethered to the pH-insensitive OmpG to demonstrate the utility of the OmpG nanopore for sensing complementary DNA and a DNA binding protein at an acidic pH.

Lignocellulosic Materials Used as Biosorbents for the Capture of Nickel (II) in Aqueous Solution

Four lignocellulosic materials (walnut shell, chestnut shell, pine wood and burnt pine wood) were analyzed as biosorbents to remove nickel ions in aqueous solution. The optimal pH condition was determined. Due to this, a range of different pHs (3.0 to 7.5) was tested. The adsorption isotherms and kinetics were established. To plot Langmuir and Freundlich isotherms, batch adsorption tests were made with variable nickel concentrations (5 to 200 mg L−1). The pseudo-first order, pseudo-second order, Elovich and intraparticle diffusion models were used to describe the kinetics, batch adsorption tests were carried out with 25 mg L−1 of nickel solution and agitation time varied from 10 to 1440 min. The specific surface area of the different materials was between 3.97 and 4.85 m2g−1 with the exception for wood with 1.74 m2g−1. The pore size was 26.54 nm for wood and varied between 5.40 and 7.33 nm for the remaining materials. The diffractograms analysis showed that all the lignocellulosic materials presented some crystalline domains with the exception of burnt pine wood which was completely amorphous. The best pH was found to be around 5.0. At this pH the adsorption was higher for chestnut shells, walnut shells, burnt pine wood and wood, respectively. All samples fitted the Langmuir model well, with R2 of 0.994 to 0.998. The sorption kinetics was well described by the pseudo-second order equation with R2 between 0.996 and 1.00. No significative differences on the surface of the materials before and after adsorption could be observed by SEM. Finally, all materials tested were able to remove nickel ions in aqueous solution.

An Eco-Friendly Terpolymer Resin: Synthesis, Characterization and Ion‐Exchange Properties

2, 2’- Biphenol-Hexamethylenediamine-formaldehyde Terpolymers (BPHDF) were synthesized by the condensation of 2, 2’- Biphenol, Hexamethylenediamine, and formaldehyde in the presence of acid catalyst with varying molar ratios of reacting monomers. Terpolymer composition has been determined on the basis of their elemental analysis and the number–average molecular weight of these resins was determined by conductometric titration in nonaqueous medium. The viscosity measurements were carried out in N, N-dimethyl formamide which indicate normal behaviour. IR spectra were studied to elucidate the structure. The terpolymer resin has been further characterized by UV–visible and 1H-NMR spectra. The surface morphology of the terpolymer resin was examined by scanning electron microscopy. One of the important applications of these terpolymers is their capability to act as chelating ion-exchangers. The newly synthesized terpolymers proved to be selective for chelating ion-exchange properties and showed a powerful adsorption towards specific metal ions like Co2+, Hg2+, Cd2+, Pb2+. A batch equilibration method was adopted to study the selectivity of the metal ion uptake involving the measurement of the distribution of the given metal ion between the polymer sample and a solution containing the metal ion over a wide range of concentrations and pHs of different electrolytes. The terpolymers showed a higher selectivity for Co2+> Hg2+> Cd2+> Pb2+.It is also observed that the amount of metal ions absorption by the BPHDF terpolymer resins increases in the order: BPHDF-3 > BPHDF-2 > BPHDF-1 due to introduction of more and more phenolic groups in terpolymer resins from BPHDF-1 to BPHDF-3.

Immobilization of α-amylase in ethylcellulose electrospun fibers using emulsion-electrospinning method

α-Amylase encapsulated in water in oil (W/O) emulsion was prepared using poly ethylene glycol (PEG 10000) (2%w/v) as water phase and ethylcellulose (EC) in ethyl acetate as oil phase at the ratio of 10:90 v/v. Next, the electrospun fibers were prepared by mixing enzyme loaded emulsion with EC solution (20%w/v) in acetic acid/ethyl acetate (20:80 v/v) at the 2:1 ratio. The emulsion showed good physical stability. The immobilized enzyme showed high activity across a board range of pHs and temperatures. The storage stability of the immobilized enzyme was 2 fold of free enzyme activity after 45 days. The residual activity of immobilized α–amylase onto of fibers after 10 and 15 repeated cycles, was approximately 100% and 50%, respectively. The results of this study indicated that the α–amylase loaded EC fibers have acceptable activity against harsh conditions and excellent reusability.

Improving photocatalyst performance of CdTiO3 via binary Co@CdTiO3 and ternary Co@CdTiO3@S nanocomposites utilizing synergistic effect of adsorption-photocatalytic under sunlight

Binary and ternary nanocomposites of Co@CdTiO 3 (Co@CTO) and Co@CdTiO 3 @S (Co@CTO@S) were synthesized via the hydrothermal method and used as photocatalysts under visible-light. The structural properties, morphology, and size of the nanocomposites were evaluated by XRD, Fe-SEM, and TEM techniques, respectively. The impurities and chemical composition of the samples were characterized by FT-IR, Map, and EDX. BET analysis was also utilized to determine the specific surface area, total pore volume, and average pore diameter of the nanocomposites. The pore size distribution of the Co@CTO and Co@CTO@S was obtained through the BJH method. Optical properties were investigated via DRS spectra and the results showed a reduction in the band-gap energy due to the penetration of cobalt and sulfur in the structure of CdTiO 3 (CTO). Zeta potential measurements were utilized for determining the surface charge showed the change from + 24 mv to − 25 mv within the pHs range of 2–10. The photocatalytic performance of the CTO, Co@CTO, and Co@CTO@S was investigated by UV-Vis spectroscopy. The Co@CTO@S nanocomposite offered the highest photocatalytic performance in degrading Crystal-Violet (CV) dye as a pollutant (> 96% during 60 min adsorption and 30 min solar irradiation). The main responsible factors for this gain could be considered as: higher surface area, the synergistic effect of the adsorption-photodegradation process, as well as reducing the band-gap energy. Kinetics studies showed that the degradation of CV by Co@CTO@S followed the pseudo-second-order kinetics with R 2 = 0.9532. Its degradation rate was 22x and 225x faster than that of Co@CTO and CTO, respectively. The investigation of reusability and stability revealed that Co@CTO@S photocatalyst remained stable after five consecutive cycles as tested by the leaching process. • Binary Co@CdTiO3 and ternary Co@CdTiO3@S nanocomposites synthesized by hydrothermal and hydrothermal/solid-state respectively. • The band-gap energy of CdTiO3 reduced due to the influence of cobalt and sulfur in the crystal lattice. • Co@CdTiO3@S nanocomposites degraded azo dye of Crytal-Violet better than Co@CdTiO3 and CdTiO3 under sunlight. • Synergistic effect of cationic and anionic phases of Co and S enhanced the photodegradation of Crystal-Violet. • Co@CdTiO3@S nanocomposites decomposed Crystal-Violet 22x and 255x times faster than Co@CdTiO3 and CdTiO3, respectively.

Synthesis of 3D Sn doped Sb2O3 catalysts with different morphologies and their effects on the electrocatalytic hydrogen evolution reaction in acidic medium

Recently, the design and synthesis of highly effective, abundant and low-cost catalysts to produce molecular hydrogen through the hydrogen evolution reaction (HER) have been studied in a wide range of pHs to replace Pt. In this work, 3D flower-like and rod-like pure Sb2O3 and Sn: Sb2O3 particles by using co-precipitation methods were efficiently synthesized for electro-catalytic energy conversion applications. The morphologies and structure of the synthesized catalysts were investigated extensively. Electrochemical studies were carried out to investigate the catalytic performance of 3D flower-like and rod-like Sn: Sb2O3 and pure Sb2O3 particles for hydrogen evolution reactions (HER) in acidic environments using 0.5 M H2SO4 electrolyte. Among the prepared particles, 3D rod-like Sn: Sb2O3 show excellent electro-catalytic hydrogen evolution reactions (HER) at 0.5 M H2SO4. Moreover, we have obtained the high stability of the electrodes during chronoamperometric studies (current v/s time) approximately 2000 s at constant potential.