Preparation of ceric oxide and cobalt sulfide-ceric oxide/cellulose-chitosan nanocomposites as a novel catalyst for efficient photocatalysis and antimicrobial study

Recent Advances of CeO2-Based Composite Materials for Photocatalytic Applications

Photocatalysis has the advantages of practical, sustainable and environmental protection, so it plays a significant role in energy transformation and environmental utilization. CeO2 has attracted widespread attention for its unique 4 f electrons, rich defect structures, high oxygen storage capacity and great chemical stability. In this paper, we review the structure of CeO2 and the common methods for the preparation of CeO2-based composites in the first part. In particular, we highlight the co-precipitation method, template method, and sol-gel method methods. Then, in the second part, we introduce the application of CeO2-based composites in photocatalysis, including photocatalytic CO2 reduction, hydrogen production, degradation, selective organic reaction, and photocatalytic nitrogen fixation. In addition, we discuss several modification techniques to improve the photocatalytic performance of CeO2-based composites, such as elemental doping, defect engineering, constructing heterojunction and morphology regulation. Finally, the challenges faced by CeO2-based composites are analyzed and their development prospects are prospected. This review provides a systematic summary of the recent advance of CeO2-based composites in the field of photocatalysis, which can provide useful references for the rational design of efficient CeO2-based composite photocatalysts for sustainable development.

Sustainable chitosan-based materials as heterogeneous catalyst for application in wastewater treatment and water purification: An up-to-date review

Water pollution is one of serious environmental issues due to the rapid development of industrial and agricultural sectors, and clean water resources have been receiving increasing attention. Recently, more and more studies have witnessed significant development of catalysts (metal oxides, metal sulfides, metal-organic frameworks, zero-valent metal, etc.) for wastewater treatment and water purification. Sustainable and clean catalysts immobilized into chitosan-based materials (Cat@CSbMs) are considered one of the most appealing subclasses of functional materials due to their high catalytic activity, high adsorption capacities, non-toxicity and relative stability. This review provides a summary of various upgrading renewable Cat@CSbMs (such as cocatalyst, photocatalyst, and Fenton-like reagent, etc.). As for engineering applications, further researches of Cat@CSbMs should focus on treating complex wastewater containing both heavy metals and organic pollutants, as well as developing continuous flow treatment methods for industrial wastewater using Cat@CSbMs. In conclusion, this review abridges the gap between different approaches for upgrading renewable and clean Cat@CSbMs and their future applications. This will contribute to the development of cleaner and sustainable Cat@CSbMs for wastewater treatment and water purification.

Rational design of full-spectrum visible-light-responsive bimetallic sulfide Bi2S3/CoS2 composites for high-efficiency photocatalytic degradation of naproxen and bacterial inactivation

Photocatalytic water decontamination has emerged as a highly promising technology for efficient and rapid water treatment, harnessing sustainable solar energy as its driving force. In this study, we prepared visible-light active Bi2S3/CoS2 composites for the degradation of naproxen (NPX) and the inactivation of Escherichia coli (E. coli). The homogeneous dispersion of CoS2 was stably integrated with Bi2S3, resulting in a significant enhancement of the specific surface area, efficient utilization of visible light, and effective separation of photogenerated charge carriers. Consequently, this synergistic photocatalytic system greatly facilitated the successful degradation of NPX and the inactivation of E. coli under visible-light irradiation. Compared to the pure Bi2S3 and CoS2 catalysts, the Bi2S3/CoS2 (1:2) composites displayed significantly enhanced photodegradation activity, achieving 96.46% (k = 0.2847 min-1) degradation of NPX within 90 min and maintaining good recyclability with no significant decline after six successive cycles. Additionally, the photocatalytic inactivation of E. coli results indicated that Bi2S3/CoS2 composites exhibited excellent performance, leading to the inactivation of 7 log10 cfu mL-1 of bacterial cells after 150 min of visible-light exposure. Scanning Electron Microscopy (SEM) and K+ ions leakage tests demonstrated that the destruction of the E. coli cell membrane structure resulted in cell death. The outcomes of this work suggest that Bi2S3/CoS2 composites hold significant potential for treating water contaminated with antibiotic and microbial pollutants.

Recent Developments and Perspectives of Cobalt Sulfide-Based Composite Materials in Photocatalysis

Photocatalysis, as an inexpensive and safe technology to convert solar energy, is essential for the efficient utilization of sustainable renewable energy sources. Earth-abundant cobalt sulfide-based composites have generated great interest in the field of solar fuel conversion because of their cheap, diverse structures and facile preparation. Over the past 10 years, the number of reports on cobalt sulfide-based photocatalysts has increased year by year, and more than 500 publications on the application of cobalt sulfide groups in photocatalysis can be found in the last three years. In this review, we initially summarize the four common strategies for preparing cobalt sulfide-based composite materials. Then, the multiple roles of cobalt sulfide-based cocatalysts in photocatalysis have been discussed. After that, we present the latest progress of cobalt sulfide in four fields of photocatalysis application, including photocatalytic hydrogen production, carbon dioxide reduction, nitrogen fixation, and photocatalytic degradation of pollutants. Finally, the development prospects and challenges of cobalt sulfide-based photocatalysts are discussed. This review is expected to provide useful reference for the construction of high-performance cobalt sulfide-based composite photocatalytic materials for sustainable solar-chemical energy conversion.

Dynamic Light Scattering: A Powerful Tool for In Situ Nanoparticle Sizing

Due to surface effects and quantum size effects, nanomaterials have properties that are vastly different from those of bulk materials due to surface effects. The particle size distribution plays an important role in chemical and physical properties. The measurement and control of this parameter are crucial for nanomaterial synthesis. Dynamic light scattering (DLS) is a fast and non-invasive tool used to measure particle size, size distribution and stability in solutions or suspensions during nanomaterial preparation. In this review, we focus on the in situ sizing of nanomaterial preparation in the form of colloids, especially for metal oxide nanoparticles (MONs). The measuring principle, including an overview of sizing techniques, advantages and limitations and theories of DLS were first discussed. The instrument design was then investigated. Ex-situ and in situ configuration of DLS, sample preparations, measurement conditions and reaction cell design for in situ configuration were studied. The MONs preparation monitored by DLS was presented, taking into consideration both ex situ and in situ configuration.

Eco-friendly cubic-ZnS coupled Cu7S4 spines on chitosan matrix: Unravelling defect-engineered nanoplatform for the photodegradation of p-chlorophenol

Novel ZnS-Cu₇S₄ nanohybrid supported on chitosan matrix, as an ideal photocatalyst, was fabricated by the sonochemical method wherein high-resolution transmission electron microscopy (HRTEM) and X-ray powder diffraction (XRD) analysis confirmed the co-existence of both ZnS and Cu₇S₄; presence of vacancy sites in ZnS was verified by electron paramagnetic resonance (EPR) analysis and their introduction could promote two-photon excitation facilitated visible light response and charge transport/separation. The type II interface is formed in the ZnS-Cu₇S₄/Chitosan heterojunction owing to interstitial states that promote charge separation. The ZnS-Cu₇S₄/Chitosan was used for the photodegradation of a pharmaceutical pollutant, p-chlorophenol (PCP); over 98.8% of PCP photodegradation was achieved under visible-light irradiation where the ensued ·O₂^- and ·OH serve a key role in the photodegradation of PCP. In vitro cytotoxicity studies substantiated that the ZnS-Cu₇S₄/Chitosan is nontoxic to the ecosystem and human beings and endowed with promising photodegradation properties and accessibility via an environmentally friendly design, bodes well for its potential remediation applications.

A new copper-supported zinc ferrite as a heterogeneous magnetic nanocatalyst for the synthesis of bis(pyrazolyl)methanes and oxidation of sulfides

In this paper, we report the synthesis of ZnFe2O4@SiO2@APTES@DHBS-Cu as a novel magnetic nanocatalyst, in a mild and green environment. The structure of the described magnetic compound was characterized by different physicochemical techniques including XRD, EDS, AAS, SEM, FT-IR, X-ray elemental mapping, TGA, and VSM analyses. The prepared magnetic nanoparticles exhibit excellent catalytic activity in synthesizing bis (pyrazolyl)methanes and oxidation of sulfide derivatives under green conditions. The heterogeneous nature of the catalyst was confirmed via the hot filtration experiment. Further, ZnFe2O4@SiO2@APTES@DHBS-Cu showed high efficiency and reusability that could be reused for at least five consecutive runs.

Ternary and Quaternary Nanocrystalline Cu-Based Sulfides as Perspective Antibacterial Materials Mechanochemically Synthesized in a Scalable Fashion

Twelve Cu-based ternary (Cu-Me₁-S, Me₁ = Fe, Sn, or Sb) and quaternary (Cu-Me₂-Sn-S, Me₂ = Fe, Zn, or V) nanocrystalline sulfides are shown as perspective antibacterial materials here. They were prepared from elemental precursors by a one-step solvent-free mechanochemical synthesis in a 100 g batch using scalable eccentric vibratory ball milling. Most of the products have shown strong antibacterial activity against Escherichia coli and Staphylococcus aureus bacteria. For instance, stannite Cu₂FeSnS₄ and mohite Cu₂SnS₃ were the most active against E. coli, whereas kesterite Cu₂ZnSnS₄ and rhodostannite Cu₂FeSn₃S₈ exhibited the highest antibacterial activity against S. aureus. In general, stannite has shown the best antibacterial properties out of all the studied samples. Five out of twelve products have been prepared using mechanochemical synthesis for the first time in a scalable fashion here. The presented synthetic approach is a promising alternative to traditional syntheses of nanomaterials suitable for biological applications and shows ternary and quaternary sulfides as potential candidates for the next-generation antibacterial agents.

In-silico identification of lysine residue for α-Amylase immobilization on dialdehyde cellulose

Enzymes are the precious gift of nature to humans. The wise utilization of enzymes may reduce energy needs of humans and the Immobilization technique can help a lot in this regard. This aspect overcomes limitations of the enzymes, therefore providing an opportunity to explore enzymatic chemistry further. In the present context, it is quite cumbersome & costly to identify the amino acid of enzymes involved in the covalent mode of Immobilization. In the present study, molecular modeling techniques were used to do this difficult task. The present work used molecular modeling methods to extract information about the immobilization of α-Amylase (E.C.3.2.1.1) on Dialdehyde Cellulose. The Lysine residue is the most probable residue to interact with Dialdehyde Cellulose. In the present work, a total of 23 lysine residues were used to study covalent binding behavior with α-Amylase. It was found that if Lys142 is involved in binding with Dialdehyde Cellulose then binding affinity (-6.1 & -5.9 kcal mol-1), as well as the involvement of amino acids of both free α-Amylase and Lys142 immobilized α-Amylase with the starch substrate, were found to be similar. The technique reported here is used for the identification of amino acid residue for the Immobilization of enzymes.

Fabrication of Cu2MoS4 decorated WO3 nano heterojunction embedded on chitosan: Robust photocatalytic efficiency, antibacterial performance, and bacteria detection by peroxidase activity

In this study, the Cu2MoS4/WO3 supported on chitosan was prepared by precipitation method, and applied to photocatalyst, antibacterial agent and biosensor. The presence of WO3 and Cu2MoS4 crystals were confirmed by XRD analysis. The elemental information was investigated by EDS. FTIR spectra shows the presence of chitosan in nanocomposites. The as-synthesized Cu2MoS4/WO3/Chitosan nanocomposites has a bandgap of 2.18 eV and it is effective for visible light condition. The average particle size of the Cu2MoS4/WO3/Chitosan is 71 nm. The photocatalysis activity Cu2MoS4/WO3/Chitosan was higher than Cu2MoS4 or WO3.The Cu2MoS4/WO3/Chitosan nanocomposites shows the highest efficiency (100%) in photocatalysis degradation of dye under visible light irradiation in 80 min. The •O2- plays a main role in degradation process. The as-synthesized Cu2MoS4/WO3/Chitosan nanocomposites depicted the antibacterial activity toward G+/- bacteria. Determination of enterococcus faecalis is important for human health. The DNA template was used to the Cu2MoS4/WO3/Chitosan nanocomposites and applied in detection of enterococcus faecalis by H2O2 and 3,3',5,5' -tetramethylbenzidine in peroxidase like activity. The detection limit of enterococcus faecalis by DNA-Cu2MoS4/WO3/Chitosan in peroxidase-like catalysis was about 55 CFU/mL. Therefore, the Cu2MoS4/WO3/Chitosan can be applied in the photocatalysis, bactericidal and peroxidase process.

Adsorption of 4-Nitrophenol on calcium alginate-multiwall carbon nanotube beads: Modeling, kinetics, equilibriums and reusability studies

In this study calcium alginate-multiwall carbon nanotube (CA/MWCNTs) was synthesized using (CA) calcium alginate and multiwall carbon nanotube (MWCNTs), and its efficiency in adsorption of 4-Nitrophenol (4-NP) in aqueous solution was studied. The structure and properties of the synthesized adsorbent were investigated using scanning electron microscope (SEM), thermal gravimetric analysis (TGA), Fourier transform infrared (FTIR), and X-ray diffraction (XRD). The experimental design was performed using Box-Behnken design (BBD) in which variables pH, CA/MWCNTs, and temperature were examined. The results of the effect of temperature on the removal efficiency of 4-NP showed that the adsorption efficiency decreases with increasing temperature. The results of nonlinear isotherm and kinetics models showed that Langmuir and pseudo-second-order models were more consistent than other models. The maximum adsorption capacity of 4-NP in this study by CA, MWCNTs, and CA/MWCNTs was 136, 168.4, and 58.8 mg/g, respectively, which indicates that the use of MWCNTs on CA could increase the adsorption capacity. The results of reuse of the synthesized adsorbent at 4-NP removal also showed that after 5 reuse of the adsorbent, the removal of 4-NP using CA/MWCNTs is reduced by about 10%, which shows that the synthesized adsorbent can be used several times to adsorb contaminants without significant reduction in the efficiency.

Metal/metal oxide nanocomposites for bactericidal effect: A review

Many microbial species causing infectious disease all over the world became a social burden and creating threat among community. These microbes possess long lifetime, enhancing mortality and morbidity rate in affected organisms. In this condition, the treatment was ineffective and more chances of spreading of infection into other organisms. Hence, it is necessary to initiate infection control efforts and prevention activities against multidrug resistant microbes, to reduce the death rate of people. Seriously concerning towards this problem progress was shown in developing significant drugs with least side effects. Emergence of nanoparticles and its novelty showed effective role in targeting and destructing microbes well. Further, many research works have shown nanocomposites developed from nanoparticles coupled with other nanoparticles, polymers, carbon material acted as an exotic substance against microbes causing severe loss. However, metal and metal oxide nanocomposites have gained interest due to its small size and enhancing the surface contact with bacteria, producing damage to it. The bactericidal mechanism of metal and metal oxide nanocomposites involve in the production of reactive oxygen species which includes superoxide radical anions, hydrogen peroxide anions and hydrogen peroxide which interact with the cell wall of bacteria causing damage to the cell membrane in turn inhibiting the further growth of cell with leakage of internal cellular components, leading to death of bacteria. This review provides the detailed view on antibacterial activity of metal and metal oxide nanocomposite which possessed novelty due to its physiochemical changes.

A potent multifunctional Ag/Co-polyvinylpyrrolidone nanocomposite for enhanced detection of Cr(III) from environmental samples and its photocatalytic and antibacterial applications

Trivalent chromium (Cr(III)) is considered to exhibit hormesis (bi-phasic dose-response) property, where low dose be beneficial and high dose shows toxic effect. The present work describe the development of a bimetallic Ag/Co-polyvinylpyrrolidone nanocomposite (Ag/Co-PVP NPs) probe to detect and quantify Cr(III) ions from aqueous samples. The hydrodynamic size and zeta potential of the particle was determined to be 29 ± 1.3 nm and -37.19 ± 2.4 mV respectively. The interaction of Cr(III) with Ag/Co-PVP probe showed drastic change in colour of NPs from dark brown to pale yellow, with corresponding blue shift, tapering width and increased peak intensity. The probe showed high specificity towards Cr(III) among the tested metal ions. A linearity was observed between various dilutions of Cr(III) ions (10 to 50 nM) and the absorbance of Ag/Co-PVP NPs at 428 nm with R² value of 0.998. The minimum detectable limit of Cr(III) was calculated to be 0.6 nM. The influence of salinity, temperature and pH on detection was studied. The probe was found to detect Cr(III) at acidic pH effectively. Competitive metal ions did not interfere the detection of Cr(III). The water sample collected from Noyyal river was taken to estimate Cr(III) by using the prepared probe to ensure practical applicability. The sample contains 9.3 nM of Cr(III) that was cross verified with AAS analysis. Hence, it is understood that the reported probe can be used to detect Cr(III) selectively with high accuracy from aqueous samples. In addition, the particles also exhibited excellent photocatalytic activity under visible light. Ag/Co-PVP nanocomposites exhibited excellent antibacterial activity against both gram +ve (B. subtilis) and gram -ve (E. coli) bacteria.

Modified nanoscale metal organic framework-based nanoplatforms in photodynamic therapy and further applications

Photodynamic therapy (PDT) has emerged as a modality in cancer treatment because it is less invasive and highly selective compared with conventional chemotherapy and radiation therapy. Nanoscale metal organic frameworks (nMOFs) have exhibited great potential for use in constructing nanoplatforms for improved PDT because of their unique structural advantages such as large surface areas, high porosities, tunable compositions and various other modifications. The large majority of current nMOF-based systems employ specific modifying groups to overcome the deficiencies previously observed when using older nMOFs in PDT. In this review, we summarize modifications to these systems such as enhancing singlet oxygen generation by introducing photoactive agents, alleviating tumor hypoxia and engineering active targeting abilities. The applications of MOF-based nanoparticles in synergistic cancer therapies that include PDT, as well as in theranostics are also discussed. Finally, we discuss some of the challenges faced in this field and the future prospects for the use of nMOFs in PDT.

Nanostructured Mg substituted Mn-Zn ferrites: A magnetic recyclable catalyst for outstanding photocatalytic and antimicrobial potentials

With recently increasing the environmental problems and expected energy crisis, it is necessary to synthesis a low-cost, efficient, and UV-light responsive photocatalyst for contaminants' degradation. The nanostructured spinel ferrite Mn_0.5Zn_0.5-xMg_xFe₂O₄ NPs (x = 0.0, 0.125, 0.25, 0.375 and 0.50) were synthesized via the sol-gel method. The crystallite size was lied in nano regime ranging from 21.8 to 36.5 nm. The surface chemical composition of the Mn_0.5Zn_0.5-xMg_xFe₂O₄ NPs was investigated via XPS analysis. Mossbauer spectra showed that the peaks were shifted to higher values of the maximum magnetic field as the Mg content increased, indicating that the crystallinity is enhanced while the crystal size is decreased. Also, various parameters such as the photocatalyst dose, dyes concentration, pH, point of zero charge, and the metals leaching were studied. The point of zero charge (PZC) has found at pH = 2.38. The Mn_0.5Zn_0.125Mg_0.375Fe₂O₄ NPs showed an excellent UV-assisted photocatalytic activity against Chloramine T (90 % removal efficiency) and Rhodamine B (95 % removal efficiency) after 80 min as compared to pure Mn_0.5Zn_0.5Fe₂O₄ ferrite NPs. Besides, it a recyclable catalyst at least four times with a negligible reduction of photocatalytic activity with slight elements leaching. Furthermore, the Mn_0.5Zn_0.25Mg_0.25Fe₂O₄ NPs showed a high antimicrobial activity towards pathogenic bacteria and yeats.

Biosynthesis of nano bimetallic Ag/Pt alloy from Crocus sativus L. extract: Biological efficacy and catalytic activity

In this project, silver‑platinum (AgPt) nanoparticles were prepared by using the Crocus sativus L. plant ethanolic extract. The AgPt nanoparticles were characterized by applying the various method as ultraviolet-visible and infrared spectroscopy, electron microscopy, and X-ray diffraction analysis. The morphology structural indicated that the AgPt nanoparticles were spherical particles with diameter about 36.0 nm. The FTIR spectroscopy shows the efficient stabilization of the AgPt nanoparticles by phytoconstituents. The Ag and AgPt nanoparticles have polyphenolic content, lower than the flavonoids and proanthocyanins contents. The AgPt nanoparticles depicted the highest antioxidant properties compared to the Ag nanoparticles and ascorbic acid. The results showed that the AgPt nanoparticles had a high antioxidant properties. In addition, the AgPt nanoparticles demonstrated the substantial antimicrobial and cytotoxic activities against pathogenic microbes and MCF-7 breast cancer cell line. The environmental chemistry analysis depicts that methyl orange can be degraded from water by catalytic degradation process with sodium borohydride. The AgPt nanoparticles were prosperous in catalytic degrading methyl orange following a first order kinetic model.

Synthesis and structure of iron–copper/hollow magnetic/metal–organic framework/coordination sites in a heterogeneous catalyst for a Fenton-based reaction

Preparation of novel hybrid catalysts with highly stable properties was conducted for wastewater remediation.