Metal nanoparticles containing chitosan wrapped cellulose nanocomposites for catalytic hydrogen production and reduction of environmental pollutants

Exploring the potential of surface-modified alginate beads for catalytic removal of environmental pollutants and hydrogen gas generation

In this study, hydrogel beads were fabricated using alginate (Algt) polymer containing dispersed nickel phthalocyanine (NTC) nanomaterial. The viscous solution of Algt and NTC was poured dropwise into a divalent Ca2+ ions, resulting in the formation of hydrogel beads known as NTC@Algt-BDs. The surface of the NTC@Algt-BDs was further modified by coating them with different types of metal ions, yielding metal-coated M+/NTC@Algt-BDs. The adsorbed metal ions i.e., Cu+2, Ag+, Ni+2, Co+2, and Fe+3 were subsequently reduced to zero-valent metal nanoparticles (M0) by NaBH4. The prepared beads were characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Initially, M0/NTC@Algt-BDs were examined for the catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). Among them, Cu0/NTC@Algt-BDs catalyst exhibited the highest reduction rate and therefore, investigated for reduction of different nitrophenols (NPs) and dyes, including 2-nitrophenol (2-NP), 2,6-dinitrophenol (2,6-DNP), methyl orange (MO), potassium ferrocyanide (PFC), congo red (CR), and acridine orange (ArO). The highest reduction rates of 2.019 and 1.394 min-1 were observed for MO and 2-NP, respectively. Furthermore, the fabricated catalysts were employed for the efficient production of H2 gas by NaBH4 methanolysis. Among which the Ag0/NTC@Algt-BDs catalyst showed excellent catalytic production of H2 gas, exhibiting the lowest activation energy (Ea) of 25.169 kJ/mol at ambient temperature. Furthermore, the impact of NaBH4 amount, and catalyst dosage on the reduction of 2-NP and H2 gas production was conducted whereas the effect of temperature on methanolysis of NaBH4 for evolution of H2 gas was studied. The amount of H2 gas was confirmed by GC-TCD system. Additionally, the recyclability of the catalyst was investigated, as it garnered significant research interest.

Effective hydrogen production and coupling degradation of organics (4-nitrophenol, methylene blue, and Rhodamine B) in wastewater by electrospun PAN@Fe0 composite nanofibers

The pursuit of clean energy generation and environmental preservation is of utmost importance for societal progress. However, couple clean energy production and pollution control is still a difficulty. In this study, a novel electrospun composite mat, with nano zero valent iron (Fe0, nZVI) encapsulated into polyacrylonitrile (PAN) nanofibers was acted as a catalyst. The activation energy (Ea) for the hydrolysis of NaBH4 to produce hydrogen is 22 kJ·mol-1, hydrogen atom utilization efficiency (HGE) of NaBH4 is 60.80%. Three kinds of organic dyes 4-nitrophenol (4-NP), methylene blue (MB), and Rhodamine B (RhB) were served as the model pollutant, to construct NaBH4-organic system for energy production and pollution reduction. The NaBH4-organic system demonstrates a collaborative capability to simultaneously remove organic pollutants and generate hydrogen, with a coupling equilibrium point between the two processes. The hydrogen generation rate (HGR) and HGE increased with the concentration of pollutants increased. The degradation of 4-NP, MB, and RhB followed pseudo-first-order kinetics, with RhB degrading dosage 20 and 44 times higher than 4-NP and MB, respectively. H2 and H· contributed to the organic degradation. nZVI directly participated in the formation H2 and H·. PAN@Fe0 possessed good recyclability and moderate cost. The degradation process adhered to the classical surface reaction controlled Langmuir-Hinshelwood (L-H) model. The integration of synergistic production capacity and pollutant degradation aligns well with the principles of green chemistry and sustainable development. This study demonstrates a novel approach to no precursor loss catalysts preparation, efficient production clean H2, advanced treatment of dye-containing wastewater, carbon neutral operation of sewage treatment plant.

Robust polymer hybrid and assembly materials from structure tailoring to efficient catalytic remediation of emerging pollutants

A massive amount of toxic substances and harmful chemicals are released every day into the outer environment, imposing serious environmental impacts on both land and aquatic animals. To date, research is constantly in progress to determine the best catalytic material for the effective remediation of these harmful pollutants. Hybrid nanomaterials prepared by combining functional polymers with inorganic nanostructures got attention as a promising area of research owing to their remarkable multifunctional properties deriving from their entire nanocomposite structure. The versatility of the existing nanomaterials' design in polymer-inorganic hybrids, with respect to their structure, composition, and architecture, opens new prospects for catalytic applications in environmental remediation. This review article provides comprehensive detail on catalytic polymer nanocomposites and highlights how they might act as a catalyst in the remediation of toxic pollutants. Additionally, it provides a detailed clarification of the processing of design and synthetic ways for manufacturing polymer nanocomposites and explores further into the concepts of precise design methodologies. Polymer nanocomposites are used for treating pollutants (electrocatalytic, biocatalytic, catalytic, and redox degradation). The three catalytic techniques that are frequently used are thoroughly illustrated. Furthermore, significant improvements in the method through which the aforementioned catalytic process and pollutants are extensively discussed. The final section summarizes challenges in research and the potential of catalytic polymer nanocomposites for environmental remediation.

Silver nanoparticle-decorated cellulose beads: Eco-friendly catalysts for efficient 4-nitrophenol reduction and antibacterial performance

This study presents an innovative and environmentally friendly method to produce fibrous cellulose beads by mechanically stirring natural fibers in an aqueous medium. Date palm fibers are transformed into uniform beads with a diameter of 1.5 to 2 mm through chemical treatment and mechanical agitation. These beads are then decorated with silver nanoparticles (Ag0 NPs) in a one-step synthesis, giving them catalytic capabilities for the reduction of 4-nitrophenol (4-NP) and antibacterial activities. Characterization techniques such as FTIR, XRD, SEM, EDX, and TGA confirmed the successful synthesis and deposition of Ag0 NPs on the cellulose beads. Tests showed complete conversion of 4-NP to 4-AP in just 7 min, with pseudo-first-order kinetics and a Kapp of 0.590 min-1. Additionally, Ag0@CB demonstrated exceptional recyclability and stability over five cycles, with minimal silver release. The beads also showed strong antibacterial activity against Escherichia coli and Staphylococcus aureus, effectively eradicating bacterial colonies in 30 min. In summary, Ag0@CB exhibits multifunctional capabilities for degrading organic pollutants and biomedical applications, offering promising potential for large-scale production and practical use in water treatment and antibacterial coatings.

Highly efficient and reusable CuAu nanoparticles supported on crosslinked chitosan hydrogels as a plasmonic catalyst for nitroarene reduction

The synthesis of CuAu-based monometallic (MNPs) and bimetallic nanoparticles (BNPs) supported on chitosan-based hydrogels for their application as catalysts is presented. The hydrogels consisted of chitosan chains cross-linked with tripolyphosphate (TPP) in the form of beads with an approximate average diameter of 1.81 mm. The MNPs and BNPs were obtained by the adsorption of metallic ions and their subsequent reduction with hydrazine, achieving a metallic loading of 0.297 mmol per gram of dry sample, with average nanoparticle sizes that were found between 2.6 and 4.4 nm. Both processes, metal adsorption and the stabilization of the nanoparticles, are mainly attributed to the participation of chitosan hydroxyl, amine and amide functional groups. The materials revealed important absorption bands in the visible region of the light spectra, specifically between 520 and 590 nm, mainly attributed to LSPR given the nature of the MNPs and BNPs inside the hydrogels. Subsequently, the hydrogels were evaluated as catalysts against the reduction of 4-nitrophenol (4NP) into 4-aminophenol (4AP), followed by UV-visible spectroscopy. The kinetic advance of the reaction revealed important improvements in the catalytic activity of the materials by synergistic effect of BNPs and plasmonic enhancement under visible light irradiation, given the combination of metals and the light harvesting properties of the nanocomposites. Finally, the catalytic performance of hydrogels containing BNPs CuAu 3:1 showed an important selectivity, recyclability and reusability performance, due to the relevant interaction of the BNPs with the chitosan matrix, highlighting the potential of this nanocomposite as an effective catalyst, with a potential environmental application.

Catalytic innovations: Improving wastewater treatment and hydrogen generation technologies

The effective reduction of hazardous organic pollutants in wastewater is a pressing global concern, necessitating the development of advanced treatment technologies. Pollutants such as nitrophenols and dyes, which pose significant risks to both human and aquatic health, making their reduction particularly crucial. Despite the existence of various methods to eliminate these pollutants, they are not without limitations. The utilization of nanomaterials as catalysts for chemical reduction exhibits a promising alternative owing to their distinguished catalytic activity and substantial surface area. For catalytically reducing the pollutants NaBH4 has been utilized as a useful source for it because it reduces the pollutants quiet efficiently and it also releases hydrogen gas as well which can be used as a source of energy. This paper provides a comprehensive review of recent research on different types of nanomaterials that function as catalysts to reduce organic pollutants and also generating hydrogen from NaBH4 methanolysis while also evaluating the positive and negative aspects of nanocatalyst. Additionally, this paper examines the features effecting the process and the mechanism of catalysis. The comparison of different catalysts is based on size of catalyst, reaction time, rate of reaction, hydrogen generation rate, activation energy, and durability. The information obtained from this paper can be used to steer the development of new catalysts for reducing organic pollutants and generation hydrogen by NaBH4 methanolysis.

Bifunctional green nanoferrites as catalysts for simultaneous organic pollutants reduction and hydrogen generation: Upcycling strategy

The upcycling strategy is an approach that includes the conversion of waste into new higher value-added products. This study reports on a new methodology for the environmentally friendly synthesis of MFe2O4 spinel nanoferrites (M = Co, Cu, Fe and Mn) to be used as catalysts applied in the upcycling method. Thus, the reduction of 4-nitrophenol (4-NP), methyl orange, and methyl red to commercially valuable compounds was evaluated, as well as the simultaneous generation of hydrogen in a short time. Therefore, an eco-friendly synthesis was proposed, according to the 12 principles of green chemistry and sustainability. Product were obtained with satisfactory properties in terms of crystallinity, magnetic particle size, and magnetization. The materials exhibited excellent performance in catalytic reduction of 4-NP, whose reduction time decreased in the order MnFe2O4 > Fe3O4 > CoFe2O4 > CuFe2O4. This behavior highlighted the CuFe2O4 nanoferrite, which achieved 4-NP reduction in just 10 s. It proved that it could also be reused for 10 consecutive cycles while maintaining its crystalline structure. The catalyst was also effective in the reduction of azo dyes and subsequent production of substituted aromatic compounds suitable for use in chemical processes. Under the optimized conditions, the green CuFe2O4 catalyst was effective in producing hydrogen by hydrolysis. HGR and activation energy (Ea) values were of the order of 19,600 mL g-1 min-1 and 25.5 kJ mol-1, respectively. The results demonstrated the potential of this simple strategy for the environmental pollutant elimination and power generation.

Catalytic polymer nanocomposites for environmental remediation of wastewater

The removal of harmful chemicals and species from water, soil, and air is a major challenge in environmental remediation, and a wide range of materials have been studied in this regard. To identify the optimal material for particular applications, research is still ongoing. Polymer nanocomposites (PNCs), which combine the benefits of nanoparticles with polymers, an alternative to conventional materials, may open up new possibilities to overcome this difficulty. They have remarkable mechanical capabilities and compatibility due to their polymer matrix with a very high surface area to volume ratio brought about by their special physical and chemical properties, and the extremely reactive surfaces of the nanofillers. Composites also provide a viable answer to the separation and reuse problems that hinder nanoparticles in routine use. Understanding these PNCs materials in depth and using them in practical environmental applications is still in the early stages of development. The review article demonstrates a crisp introduction to the PNCs with their advantageous properties as a catalyst in environmental remediation. It also provides a comprehensive explanation of the design procedure and synthesis methods for fabricating PNCs and examines in depth the design methods, principles, and design techniques that guide proper design. Current developments in the use of polymer nanocomposites for the pollutant treatment using three commonly used catalytic processes (catalytic and redox degradation, electrocatalytic degradation, and biocatalytic degradation) are demonstrated in detail. Additionally, significant advances in research on the aforementioned catalytic process and the mechanism by which contaminants are degraded are also amply illustrated. Finally, there is a summary of the research challenges and future prospects of catalytic PNCs in environmental remediation.

The Competition between 4-Nitrophenol Reduction and BH4- Hydrolysis on Metal Nanoparticle Catalysts

Assessing competitive environmental catalytic reduction processes via NaBH4 is essential, as BH4- is both an energy carrier (as H2) and a reducing agent. A comprehensive catalytic study of the competition between the borohydride hydrolysis reaction (BHR, releasing H2) and 4-nitrophenol reduction via BH4- on M0- and M/M' (alloy)-nanoparticle catalysts is reported. The results reveal an inverse correlation between the catalytic efficiency for BH4- hydrolysis and 4-nitrophenol reduction, indicating that catalysts performing well in one process exhibit lower activity in the other. Plausible catalytic mechanisms are discussed, focusing on the impact of reaction products such as 4-aminophenol and borate on the rate and yield of BH4- hydrolysis. The investigated catalysts were Ag0, Au0, Pt0, and Ag/Pt-alloy nanoparticles synthesized without any added stabilizer. Notably, the observed rate constants for the 4-nitrophenol reduction on Ag0, Ag-Pt (9:1), and Au0 are significantly higher than the corresponding rate constants for BH4- hydrolysis, suggesting that most reductions do not proceed through surface-adsorbed hydrogen atoms, as observed for Pt0 nanoparticles. This research emphasizes the conflicting nature of BH4- hydrolysis and reduction processes, provides insights for designing improved catalysts for competitive reactions, and sheds light on the catalyst properties required for each specific process.

Metal/metal oxide-carbohydrate polymers framework for industrial and biological applications: Current advancements and future directions

Recently, the development and consumption of metal/metal oxide carbohydrate polymer nanocomposites (M/MOCPNs) are withdrawing significant attention because of their numerous salient features. Metal/metal oxide carbohydrate polymer nanocomposites are being used as environmentally friendly alternatives for traditional metal/metal oxide carbohydrate polymer nanocomposites exhibit variable properties that make them excellent prospects for a variety of biological and industrial uses. In metal/metal oxide carbohydrate polymer nanocomposites, carbohydrate polymers bind with metallic atoms and ions using coordination bonding in which heteroatoms of polar functional groups behave as adsorption centers. Metal/metal oxide carbohydrate polymer nanocomposites are widely used in woundhealing, additional biological uses and drug delivery, heavy ions removal or metal decontamination, and dye removal. The present review article features the collection of some major biological and industrial applications of metal/metal oxide carbohydrate polymer nanocomposites. The binding affinity of carbohydrate polymers with metal atoms and ions in metal/metal oxide carbohydrate polymer nanocomposites has also been described.

Adsorption of Magenta Dye on PbO Doped MgZnO: Interpretation of Statistical Physics Parameters Using Double-Layer Models

This article reports the synthesis of PbO doped MgZnO (PbO@MgZnO) by a co-precipitation method, followed by an ultrasonication process. PbO@MgZnO demonstrates a significant adsorption capability toward Magenta Dye (MD). The greatest adsorption capability was optimized by varying parameters such as pH, MD concentration, and adsorbent dose. The kinetics study illustrates that the adsorption of MD on PbO@MgZnO follows the pseudo-second-order. The isotherm study revealed that Langmuir is best fitted for the adsorption, but with little difference in the R² value of Langmuir and Freundlich, the adsorption process cloud be single or multi-layer. The maximum adsorption capacity was found to be 333.33 mg/g. The negative ΔG refers to the spontaneity of MD adsorption on PbO@MgZnO. The steric parameters from statistical physics models also favor the multi-layer adsorption mechanism. As a function of solution temperature, the parameter n pattern has values of n = 0.395, 0.290, and 0.280 for 298, 308, and 318 K, respectively (i.e., all values were below 1). Therefore, horizontal molecule positioning and multiple locking mechanisms were implicated during interactions between MD and PbO@MgZnO active sites.

Facile synthesis of Cu NPs@Fe3O4-lignosulfonate: Study of catalytic and antibacterial/antioxidant activities

Environmental pollution is one of the important concerns for human health. There are different types of pollutants and techniques to eliminate them from the environment. We hereby report an efficient method for the remediation of environmental contaminants through the catalytic reduction of the selected pollutants. A green method has been developed for the immobilization of copper nanoparticles on magnetic lignosulfonate (Cu NPs@Fe₃O₄-LS) using the aqueous extract of Filago arvensis L. as a non-toxic reducing and stabilizing agent. The characterization of the prepared Cu NPs@Fe₃O₄-LS was achieved by vibrating sample magnetometer (VSM), Fourier-transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), high resolution TEM (HRTEM), X-ray diffraction (XRD), scanning TEM (STEM), thermogravimetry-differential thermal analysis (TG/DTA), fast Fourier transform (FFT), energy-dispersive X-ray spectroscopy (EDS), and X-ray photoelectron (XPS) analyses. The synthesized Cu NPs@Fe₃O₄-LS was applied as a magnetic and green catalyst in the reduction of Congo Red (CR), 4-nitrophenol (4-NP), and methylene blue (MB). The progress of the reduction reactions was monitored by UV-Vis spectroscopy. Finally, the biological properties of the Cu NPs@Fe₃O₄-LS were investigated. The prepared catalyst demonstrated excellent catalytic efficiency in the reduction of CR, 4-NP, and MB in the presence of sodium borohydride (NaBH₄) as the reducing agent. The appropriate magnetism of Cu NPs@Fe₃O₄-LS made its recovery very simple. The advantages of this process include a simple reaction set-up, high and catalytic antibacterial/antioxidant activities, short reaction time, environmentally friendliness, high stability, and easy separation of the catalyst. In addition, the prepared Cu NPs@Fe₃O₄-LS could be reused for four cycles with no significant decline in performance.

Application of Metal Nanoparticles for Production of Self-Sterilizing Coatings

Metal nanoparticles (NPs) are increasingly being used in many areas, e.g., industry, pharmacy, and biomedical engineering. NPs can be obtained through chemical and biological synthesis or using physical methods. AgNPs, AuNPs, CuNPs, FeNPs, MgNPs, SnO2NPs, TiO2NPs, and ZnONPs are the most commonly synthesized metal nanoparticles. Many of them have anti-microbial properties and documented activity supported by many tests against some species of pathogenic bacteria, viruses, and fungi. AgNPs, which are used for the production of commercial self-sterilizing packages, are one of the best-explored nanoparticles. Moreover, the EFSA has approved the use of small doses of silver nanoparticles (0.05 mg Ag·kg−1) to food products. Recent studies have shown that metal NPs can be used for the production of coatings to prevent the spread of the SARS-CoV-2 virus, which has caused the global pandemic. Some nanoparticles (e.g., ZnONPs and MgONPs) have the Generally Recognized As Safe (GRAS) status, i.e., they are considered safe for consumption and can be used for the production of edible coatings, protecting food against spoilage. Promising results have been obtained in research on the use of more than one type of nanometals, which prevents the development of pathogen resistance through various mechanisms of inactivation thereof.

Highly biocompatible formulations based on Arabic gum Nano composite hydrogels: Fabrication, characterization, and biological investigation

In the study, fabrication of Arabic gum (AG) hydrogels via reverse micellization method is reported. AG hydrogels were utilized as capping agents to encapsulate zinc sulphide (ZnS), and cadmium sulphide (CdS) nanoparticles via in-situ reduction. Pristine and nanocomposite hydrogels (AG-ZnS and AG-CdS) were characterized through SEM, EDX, TEM, XRD, FTIR, TGA, UV/Visible, and photoluminescence spectroscopy. The hydrogels were subjected to multiple biological assays including antimicrobial, antioxidant, and anti-diabetic formulation, in addition to biocompatibility test. The hydrogels were found to be more effective against bacterial and fungal strains. For instance, AG-ZnS exhibited excellent growth inhibition activity against Escherichia coli (ZoI: 12 ± 1.04 mm) and Candida albicans (35 ± 0.94 mm). Likewise, the nanocomposites hydrogel also displayed excellent DPPH and ABTS free radical scavenging capacity, total antioxidant capacity (TAC), and total reducing power (TRP) ability. Among the hydrogels, AG-ZnS demonstrated considerable α-amylase, and α-glucosidase inhibition potential. Above all, the hydrogels were found highly compatible with human red blood cells (hRBCs). Owing to remarkable antioxidant, antibacterial, antifungal, and bio-compatible nature, the fabricated nanocomposites hydrogels have the potential to be explored in tissue engineering, wound healing, drug delivery, and in environmentally friendly hygiene products.

Nanoarchitectured Cu based catalysts supported on alginate/glycyl leucine hybrid beads for tainted water treatment

Water pollution reached worrying point due to different dye pollutants which demands an instant solution. One of the best ways to manage water pollutants is their reduction and decolorization to less-toxic and useful compounds. However, reduction process requires an effective, stable, and recyclable catalyst to reduce such pollutants more effectively. Metal nanoparticles (M⁰) are highly effective catalysts but separation of nanoparticles after reaction is difficult and requires a high-speed centrifugation. If loaded on polymer-beads, they can be easily separated from the reaction-mixture. Hearin, alginate/glycyl leucine (AGL) hybrid-beads were prepared, and copper nanoparticles (Cu⁰) were grown on it by simple process. M⁰/AGL bead catalysts were tested toward reducing various toxic compounds. Among all developed composite-beads, the catalytic performance of Cu⁰/AGL was highest in terms of reduction kinetics. After initial screening for different pollutants, Cu⁰/AGL was much more effective for MO reduction, thus, all optimized different parameters i.e., catalyst dosage, stability, amount of reducing-agent and recyclability were experimentally determined. The Cu⁰/AGL showed high-rate constants (k_app) of 0.7566 and 2.9506 min^-1 depending on beads content. The reusability of the Cu⁰/AGL catalysts up to the 7^th cycle has been checked. With the use of AGL as support for the Cu nanoparticles, not only the catalytic activity was retained for longer times during reusability, but it helped in their easy separation.

Copper Oxide-Antimony Oxide Entrapped Alginate Hydrogel as Efficient Catalyst for Selective Reduction of 2-Nitrophenol

Copper oxide-antimony oxide (Cu₂O-Sb₂O₃) was prepared and entrapped inside Na-alginate hydrogel (Alg@Cu₂O-Sb₂O₃). The developed Alg@Cu₂O-Sb₂O₃ was used as catalytic reactor for the reduction of 4-nitrophenol (4-NP), 2-nitrophenol (2-NP), 2,6-dinitrophenol (2,6-DNP), methyl orange (MO), congo red (CR), acridine orange (AO), methylene blue (MB) and potassium ferricyanide (K₃[Fe(CN)₆]). Alg@Cu₂O-Sb₂O₃ was found to be selective and more efficient for the reduction of 2-NP among all the pollutants. Therefore, 2-NP was selected for a detailed study to optimize various parameters, e.g., the catalyst amount, reducing agent concentration, 2-NP concentration and recyclability. Alg@Cu₂O-Sb₂O₃ was found to be very stable and easily recyclable for the reduction of 2-NP. The Alg@Cu₂O-Sb₂O₃ nanocatalyst reduced 2-NP in 1.0 min, having a rate constant of 3.8187 min⁻¹.

Evaluation of the multifunctional activity of silver bionanocomposites in environmental remediation and inhibition of the growth of multidrug-resistant pathogens

Imperata cylindrica cellulose supported Ag bionanocomposites purified industrial water and controlled the contagious diseases with high potential activity.

Biopolymer-derived (nano)catalysts for hydrogen evolution via hydrolysis of hydrides and electrochemical and photocatalytic techniques: A review

Over the course of a few decades, the concern of environmental damages of fossil fuels, an increase in CO₂ emission and a decrease of hydrogen have been growing more and more. Accordingly, hydrogen production is a crucial issue nowadays. Different polymers are applied to attain the purpose. Among all polymers, biodegradables polymers are the best choices to develop the main aim. Polysaccharides and proteins are biodegradable polymers with unique places and advantages with regards to their ecofriendly properties. There are different techniques to apply and achieve the foremost purpose. It is worthwhile to mention that green and facile methods are always attracting attention in different aspects and fields. The three non-polluting and economical techniques, that is, electrochemical hydrogen evolution reaction (HER), photocatalytic technique, and hydrolysis of hydrides, are reviewed in this paper. This review helps researchers, who are environment supporters, to evaluate and choose the most ecological biopolymers and processes in their work.

Recent developments of nanocatalyzed liquid-phase hydrogen generation

Hydrogen is the most effective and sustainable carrier of clean energy, and liquid-phase hydrogen storage materials with high hydrogen content, reversibility and good dehydrogenation kinetics are promising in view of "hydrogen economy". Efficient, low-cost, safe and selective hydrogen generation from chemical storage materials remains challenging, however. In this Review article, an overview of the recent achievements is provided, addressing the topic of nanocatalysis of hydrogen production from liquid-phase hydrogen storage materials including metal-boron hydrides, borane-nitrogen compounds, and liquid organic hydrides. The state-of-the-art catalysts range from high-performance nanocatalysts based on noble and non-noble metal nanoparticles (NPs) to emerging single-atom catalysts. Key aspects that are discussed include insights into the dehydrogenation mechanisms, regenerations from the spent liquid chemical hydrides, and tandem reactions using the in situ generated hydrogen. Finally, challenges, perspectives, and research directions for this area are envisaged.

Carboxymethyl cellulose nanocomposite beads as super-efficient catalyst for the reduction of organic and inorganic pollutants

Carboxymethyl cellulose/copper oxide-nickel oxide (CMC/CuO-NiO) nanocomposite beads were prepared by facile, simple and environmentally friendly method. Initially, CuO-NiO was prepared and applied for the catalytic reduction of 4-nitrophenol (4-NP). The results showed that CuO-NiO demonstrate high catalytic activity toward the reduction of 4-NP to 4-aminophenol (4-AP) with a rate constant of 2.97 × 10^-2 s^-1. Further, CuO-NiO were well-dispersed in the polymeric matrix of carboxymethyl cellulose to prepare CMC/CuO-NiO beads. CMC/CuO-NiO nanocomposite beads were also applied to catalyze the reduction of potassium ferrocyanide (K₃Fe (CN)₆), 4-NP, Congo red (CR) and Eosin yellow (EY) in the presence of sodium borohydride. Experimental data indicated that CMC/CuO-NiO nanocomposite has higher catalytic activity and high rate constant compared to CuO-NiO. The rate constant found to be 6.88 × 10^-2, 6.27 × 10^-2, 1.89 × 10^-2 and 2.43 × 10^-2 for K₃Fe(CN)₆, 4-NP, CR and EY, respectively, using 5 mg CMC/CuO-NiO beads. FE-SEM, EDX, FTER, XRD and XPS were used to characterize the nanocomposites. CMC/CuO-NiO beads catalytically reduced up to 95-99% of K₃Fe(CN)₆, 4-NP, CR and EY within 40, 60, 120 and 120 s. CMC/CuO-NiO beads were found more selective for the reduction of 4-NP. The catalytic reduction performance of CMC/CuO-NiO beads was optimized by studying the influence of different parameters on the catalytic reduction of 4-NP. Hence, the effective and super catalytic performance toward the reduction of different organic and inorganic pollutants makes CMC/CuO-NiO beads a smart material and suitable for numerous scientific and industrial applications and may be used as an alternative to high-cost commercial catalysts.

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.