Nanocomposite Catalyst Research Articles

Visible-light-induced electron density enrichment of the active sites in the core-satellite structured CuWO4@NiO for fast hydrogen generation from ammonia borane methanolysis

Catalytic dehydrogenation of ammonia borane (AB) is an integrated technology for producing hydrogen with promising applications in mobile fuel cells. However, its commercial prospect is significantly hampered by the high expenditure of precious metal catalysts. Herein, a low-cost and efficient Z-schemed core-satellite structured CuWO4@NiO nanocomposite catalyst was developed for the methanolysis of AB for fast hydrogen production. The experimental and theoretical calculation results revealed charge transfer between CuWO4 (core) and NiO (satellite), thus creating active Ni and Cu sites for the adsorption and activation of methanol and AB, respectively. When the CuWO4@NiO catalyst was irradiated with visible light, numerous photogenerated electrons were accumulated in the conduction band of NiO of CuWO4@NiO by virtue of the special Z-scheme heterojunction, resulting in the electron density enrichment of Ni sites. The electron-enriched Ni sites effectively activated the adsorbed methanol, thus making the O–H bond cleavage easier, which was identified as the rate-determining step in AB methanolysis using kinetic isotope effect experiments. Based on the special electronic and energy band structures, our CuWO4@NiO catalyst exhibited outstanding catalytic activity with a turnover frequency of 26.5 min−1 in AB methanolysis, surpassing most noble-metal-free catalysts reported in the literature. Our findings show that visible light can be applied as a useful tool to optimize the electronic states of both active sites of catalysts and adsorbed reactants. This study provides insight into the design of more efficient catalytic systems toward AB methanolysis for fast hydrogen evolution.

Rare earth lanthanum doped catalyst for photocatalytic degradation of fleroxacin

The production and abuse of fluoroquinolones have caused enormous environmental pollution, and there is an urgent need for a simple and efficient method to solve this problem. In this paper, a rare earth lanthanum doped nanocomposite catalyst was synthesized. The dendritic structure of graphite carbon nitride (g-C3N4) can better wrap polypyrrole (PPy) and titanium dioxide (TiO2). The composite material was observed to be aggregated under electron microscope. TiO2 and PPy with sizes of approximately 10 and 100 nm, respectively, are evenly distributed in the pore-rich material. On the surface of the composite, there are abundant with a pore diameter of 3.75 nm. The introduction of rare earth La provides a new energy level for the band gap of TiO2 and g-C3N4 matrix composites. And the band-gap energy (Eg) reached 2.63 eV. La can promote electron hole separation and inhibit its recombination, thereby improving the photocatalytic property. The degradation rate of TGPL to FLE reached 81%. In addition, ultra-performance liquid chromatography tandem mass-spectrometry (UPLC-MS) analysis of the degradation of antibiotic fleroxacin (FLE) by this catalyst showed that the piperazine ring and the N1 side chain first reacted, and then gradually degraded. This study provides a broad prospect for the preparation of highly efficient photocatalysts.

Recoverable Nanocatalyst for Regioselective Triazoles Synthesis: Lignin‐Copper(I) Nanomagnetic Composite

AbstractIn this paper, a novel efficient utilization of lignin‐based nanomagnetic copper (I) is presented as an eco‐friendly recoverable catalyst. We report a simple one‐pot synthesis of magnetic copper chloride (I) composite by using lignin as a reducing agent and heterogenized support. The copper (I) nanocomposite shows high catalytic potential in one‐pot three component click reaction for synthesis of 1,2,3‐triazoles, with excellent turnover efficiency even after 4 cycles in green conditions. The lignin‐copper (I) chloride magnetic nanocomposite catalyst demonstrates highly efficient, stable and recyclable copper (I), and cost effectiveness advantages. The catalyst is easily recovered by an external magnetic field, and therefore, time and energy are saved since there is no filtration or decantation technique. Also, the stable nanomagnetic copper (I) can be handily prepared and applied for large scale operations. Besides, due to totally clear of nanomagnetic copper (I) away from the reaction media, the desired highly pure products can be achieved in excellent yields. High thermal stability of nanomagnetic copper (I) turns its ability to be useable in organic reactions under high temperatures. According to high dispersibility in aqueous solvent, nanomagnetic copper (I) can be utilized as highly efficient catalyst. The prepared composite is characterized by SEM, TEM, XRD, EDX, TGA, VSM and FT‐IR.

Ni nanowires decorated with Pd nanoparticles as an efficient nanocatalytic system for Suzuki coupling of anisole derivatives

Suzuki-Miyaura reaction enables the formation of biaryl compounds containing diverse functional groups. This work reports the development of a nanocatalytic system, which enhances the coupling of anisole derivatives using this reaction framework. Composite nanocatalysts were prepared by decorating nickel nanowires (Ni NWs) made in-house with spherical palladium nanoparticles (Pd NPs). Sonochemical deposition of noble catalytic centers on metallic nanowires proved to be fast and effective under mild conditions. Precise control of the concentration of Pd NPs on the nanowire surface enabled studying the impact of the content of noble metal on the reaction course. The lowest evaluated load of Pd (0.34 %) exhibited the best catalytic performance. Moreover, it was noted that the application of microwaves considerably increased the catalytic activity of the system due to the formation of hot spots on Pd NPs. As a result, the reaction times were shortened substantially without negatively influencing the yields of the transformations. The proposed novel approach for nanocatalyst design should inspire further studies in modern organic chemistry, especially since the proposed catalytic system is highly efficient and entirely reusable.

Photocatalytic reduction of CO2 in aqueous phase using amino-functionalized MOFs loaded with hydroxy-functionalized graphene quantum dots

Hydroxy-functionalized graphene quantum dots (OH-GQDs) were loaded onto NH2-MIL-101(Fe) to prepare a novel binary OH-GQDs/NH2-MIL-101(Fe) (OGNM) composite with a simple solvothermal method. The obtained catalysts were characterized by SEM, TEM, XRD, FI-IR, XPS and BET to analyze the morphology, elemental composition, and specific surface area of the composite material. Notably, the morphology and micro-structures of OGMM-3 exhibited that OH-GQDs evenly dispersed on the surface of hexagonal micropillar NH2-MIL-101(Fe). The nanocomposite catalysts were tested in a photocatalytic CO2 reduction system using water and acetonitrile as solvents, without additional sacrificial agents. OGNM-3 composite possessed the optimum photoreduction CO2 activity, with a CO yield of 128.68 μmol·g−1 within 10 h, which was 5.3 times higher than that of pure NH2-MIL-101(Fe). After three cycles of reuse, the catalyst still maintained catalytic activity without any significant changes in its crystal structure, morphology or functional groups. In summary, this study proposed a design for synthesizing binary OGNM photocatalysts, offering useful insights for cost-effectively address CO2 emissions in greenhouse gas emissions.

Green Synthetic Approaches of 2-Hydrazonothiazol-4(5H)-ones Using Sustainable Barium Oxide-Chitosan Nanocomposite Catalyst.

The diverse applications of metal oxide-biopolymer matrix as a nanocomposite heterogenous catalyst have caused many researches to scrutinize the potential of this framework. In this study, a novel hybrid barium oxide-chitosan nanocomposite was synthesized through a facile and cost-effective co-precipitation method by doping barium oxide nanoparticles within the chitosan matrix at a weight percentage of 20 wt.% BaO-chitosan. A thin film of the novel hybrid material was produced by casting the nanocomposite solution in a petri dish. Several instrumental methods, including Fourier-transform infrared (FTIR), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD), were used to analyze and characterize the structure of the BaO-CS nanocomposite. The chemical interaction with barium oxide molecules resulted in a noticeable displacement of the most significant chitosan-specific peaks in the FTIR spectra. When the surface morphology of SEM graphs was analyzed, a dramatic morphological change in the chitosan surface was also discovered; this morphological change can be attributed to the surface adsorption of BaO molecules. Additionally, the patterns of the XRD demonstrated that the crystallinity of the material, chitosan, appears to be enhanced upon interaction with barium oxide molecules with the active sites, OH and NH2 groups, along the chitosan backbone. The prepared BaO-CS nanocomposite can be used successfully as an effective heterogenous recyclable catalyst for the reaction of N,N'-(alkane-diyl)bis(2-chloroacetamide) with 2-(arylidinehydrazine)-1-carbothioamide as a novel synthetic approach to prepare 2-hydrazonothiazol-4(5H)-ones. This new method provides a number of benefits, including quick and permissive reaction conditions, better reaction yields, and sustainable catalysts for multiple uses.

THE SCIENTIFIC BASIS OF INDUSTRIAL APPLICATION OF THE PROCESS OF SELECTIVE HYDROGENATION OF BENZENE IN DIFFERENT CATALYTIC SYSTEMS

Pollution of the environment with substances obtained in the production of oil and other products in various industries forces us to take measures to solve environmental problems that have become relevant in recent years. Arenes, belonging to the class of petroleum-derived aromatic hydrocarbons, are very life-threatening substances due to their carcinogenic effects. In this regard, one of the important issues is the release of benzene, a special representative of arenes, from its carcinogenic effect as a toxic and volatile compound, and its use in the production of cyclohexane, which is the main raw material for the production of caprolactam and nylon. The selectivity of the hydrogenation of benzene and the high yield of cyclohexane, the target product, depend on the reaction conditions and the choice of catalysts. In recent years, the application of polymer and zeolite nanocomposite catalysts, as well as modified metal polymer-based catalysts, in obtaining highly active and selective catalysts for the purpose of effective implementation of aromatic hydrocarbon hydrogenation processes is of great interest. Thus, naphthenic hydrocarbons are considered the main starting materials for the synthesis of various classes of compounds. Derivatives of these compounds are used in the pharmaceutical industry as special-purpose caprolactam, adipic acid, cyclohexanone, as a solvent for essential oils, varnishes, paints, as an extractant, etc. are used in synthesis. As a result of investigating the catalytic properties of polymer-mineral catalysts in the benzene hydrogenation reaction, it was determined that these reactions show selectivity in the direction of cyclohexane formation in narrow-pore zeolites (mordenite, clinoptilolite)In the presented work, the main information was collected by analyzing the literature on the work carried out in this direction

Synthesising nanocomposite Co2SnO4@rGO for peroximonosulphate activation in a hybrid ozonation system to effectively degrade cefalexin from wastewater

This study successfully developed Co2SnO4@rGO nanocomposites at various composite ratios of Co2SnO4 and rGO using the sol-gel method. These nanocomposites were then used as heterogeneous catalysts to activate PMS in the heterogeneous catalytic oxidation of Co2SnO4@rGO/PMS as well as the hybrid ozonation system O3/Co2SnO4@rGO/PMS to degrade cefalexin (CFX). The physical-chemical characteristics of the fabricated catalysts were evaluated through nitrogen adsorption-deadsorption, SEM images, EDS mapping, and XRD. The catalytic activity of the nanocomposite was investigated in a degradation reaction of CFX from an aqueous solution. Besides this, CFX degradation kinetics were determined by fitting experimental data with a first-order model. The results showed that at the composite ratio of 2-Co2SnO4 and 1-rGO for CFX degradation had the highest efficiency reaching 95.07 and 99.07% for Co2SnO4@rGO/PMS and O3/Co2SnO4@rGO/PMS systems, respectively. The degradation of CFX in the O3/Co2SnO4@rGO/PMS system was higher than that of Co2SnO4@rGO/PMS. The results were due to a remarkable increase in SBET in 2-Co2SnO4@1-rGO compared to both Co2SnO4 and rGO, facilitating a catalytic reaction occurring on the catalyst’s surface. Moreover, the coupling between O3 and Co2SnO4@rGO/PMS generated a synergetic effect leading to the generation of more *SO4- and *OH radicals, which enhanced the CFX degradation rate in the hybrid ozonation system. These primary findings illustrated that the nanocomposite catalyst 2-Co2SnO4@1-rGO was feasible for the activation of PMS in hybrid ozonation to effectively degrade antibiotic residues from wastewater.

Hydrogen production from Al catalytic hydrolysis using highly active Nano composite CaO-AlOOH/Graphene oxide (GO) catalysts derived from eggshell and cauliflower stems

The hydrolysis of lightweight Al-based materials to produce hydrogen is a promising technology for compact hydrogen fuel cell production. However, developing nanostructures on a wide scale and at a low cost remains a major challenge. Herein, the high catalytic effect of CaO-γ-AlOOH/Graphene Oxide (GO) Nanocomposites (NCs) catalyst for hydrogen generation from Al and H2O reaction is discussed. These γ-phase aluminum oxyhydroxide Nanorods (NRs) (γ-AlOOH) on GO were synthesized through a simple hydrothermal method. High crystalline CaO-γ-AlOOH/GO NCs prepared bya mechanical grainingwithCaO nanoparticles (NPs). Experimental results show that small amounts of GO and CaO composite into γ-AlOOH NRs have high catalytic performance on the Al/H2O reaction for hydrogen generation at 25℃. In the catalysis process, the presence of oxygen on the catalyst surface promotes the formation of hydroxyl groups through a chemisorption process, further enhancing the catalytic activity. Because of high OH– concentrations in the local domain with a rise in the amount of Al(OH)3 precipitate byproduct, Al corrodes quickly and totally in a weak alkaline solution (pH < 8) after several contributions of Al batches. Accordingly, this research developed an excellent prediction for considering the Al reaction rate with H2O using CaO and/or GO composite crystalline γ-AlOOH catalyst.

Nano-composite rGO-Ag-Cu-Ni mediated photocatalytic degradation of anthracene and benzene

Polycyclic aromatic hydrocarbons (PAHs) are omnipresent, persistent, and carcinogenic pollutants continuously released in the atmosphere due to the rapid increase in population and industrialization worldwide. Hence, there is an ultimate rise in concern about eliminating the toxic PAHs and their related aromatic hydrocarbons from the air, water, and soil environment by employing efficient removal technologies using nanoparticles as a catalyst. Here, the degradation of selective PAHs viz., anthracene and benzene using laboratory synthesized rGO-Ag-Cu-Ni nanocomposite (catalyst) was studied. Characterization studies revealed the nanocomposites exhibited surface plasma resonance at 350 - 450 nm, confirming the presence of Ag, Cu, and Ni metal ions embedded on the reduced graphene substrate. It was found that the nanocomposites synthesized were spherical, amorphous in nature, and aggregated together with measurements ranging from 423 to 477 nm. An SEM-EDX analysis of the nanocomposite demonstrated that it contained 25.13% O, 14.24% Ni, 27.79% Cu, and 32.84% Ag, which confirms the synthesis of the nanocomposite. Crystalline, sharp nanocomposites of average size 17–41 nm with an average diameter of 118.5 nm (X-ray diffraction and DLS) were observed. FTIR spectra showed that the nanocomposites had the functional groups alkanes, alkenes, alkynes, carboxylic acids, and halogen derivatives. Batch adsorption studies revealed that the maximum degradation achieved at optimum nano-composite concentration of 10 μg/mL, pH value of 5, PAHs concentration of 2 μg/mL and effective irradiation source being UV radiations in the case of both benzene and anthracene pollutants. The degradation of benzene and anthracene followed Freundlich & Langmuir isotherm with the highest R2 value of 0.9894 & 0.9885, respectively. Adsorption kinetic studies under optimum conditions revealed that the adsorption of both benzene and anthracene followed Pseudo-second order kinetics. Antimicrobial studies revealed that the synthesized nano-composite exhibited potential antimicrobial activity against Gram positive bacterium (Bacillus subtilis, Staphylococcus aureus), Gram negative bacterium (Klebsiella pneumonia, Escherichia coli) and fungal strain (Aspergillus niger) respectively. Thus, the synthesized rGO-Ag-Cu-Ni nano-composite acts as an effective antimicrobial agent as well as a PAHs degrading agent, helping to overcome antibiotics resistance and to mitigate the overgrowing PAHs pollution in the environment.

Metal Composite Nano-Catalyst Enhanced Solid Oxide Fuel Cell Anodes for Improved Performance and Stability with Hydrocarbon Containing Fuels

Implementation of nano-catalyst materials into solid oxide fuel cell (SOFC) electrodes to improve performance and stability has been widely studied. Addition of the nano-catalysts into an electrode structure serves to enhance the electrochemical performance of the SOFC by increasing the Triple Phase Boundary (TPB) area, improving redox stabilization, and modifying reaction kinetics of hydrocarbon gasses that cause anode degradation due to carbon deposition.SOFCs operating upstream of a reformer need to exhibit good tolerance to any hydrocarbon components that may make their way to the stack. Typical Ni-based cermet anodes suffer from anode deactivation due to carbon build up under hydrocarbon flows. Carbon builds up and covers the TPB area which results in poor electrochemical performance. Larger carbon deposits can block pores within the anode microstructure which leads to gas diffusion issues. Carbon buildup also causes mechanical stresses to the electrode due to volumetric changes which can lead to fracture and complete failure of the cell.This work studied nano-catalyst decoration of the Ni-based cermet anodes with catalysts that promote internal reforming to protect against coking. Addition of active metal components (such as Co, Ge, Sn), and ceramic reforming promoters (such as CeO2, MgO) were investigated. Multi-component systems with several catalysts were also examined.Uniform incorporation of nano-catalyst into the anode microstructure was achieved through a patented liquid phase surfactant assisted process (using various catechol surfactants). Deposition loading densities and distribution of nanoparticles was controlled by altering the surfactant and catalyst solution concentrations.Nano-catalyst depositions were characterized through Scanning Electron Microscope (SEM) for imaging, Atomic Force Microscopy (AFM) for topographical analysis, and Energy-Dispersive X-ray Spectroscopy (EDS) for chemical characterization. Figure 1 shows SEM imaging of nano catalyst distribution of cerium oxide (CeO2) and cobalt oxide (CoO) co-deposition within an anode structure. A uniform distribution of nano-sized catalyst materials is observed.Accelerated evaluation of nano-catalysts for SOFCs was completed through symmetrical anode tests, where a symmetrical anode cell was subjected to hydrocarbon impurity at SOFC operating temperatures and electrochemical impedance spectroscopy (EIS) characterization was done over time. The best catalyst systems were down selected and long-term SOFC tests were completed with current-voltage-power (I-V-P) and EIS evaluation. Post-mortem microstructure and chemistry characterizations were also used in analysis.Uniform nano catalyst distribution of CeO2 and CoO within the anode structure demonstrated greater than 50% sustained improvement in harsh environment, long-term tests where the cell was subjected to 40% CH4 for 50+ h. Figure 1

Construction of ZnFe2O4/g-C3N4 nanocomposite catalyst for degradation of organic compound through photodegradation and heterogeneous Fenton oxidation

ZnFe2O4/g-C3N4 heterojunction nanocomposite photocatalyst was prepared by one-step solvothermal method using graphite carbon nitride (g-C3N4) and zinc ferrate (ZnFe2O4), and characterized by SEM/EDX, XRD, FT-IR, Zeta potential, and VSM. The cationic-dye methylene blue (MB) was selected as the target pollutant for photocatalytic degradation and the degradation mechanism of the heterogeneous nanocomposite photocatalyst was analyzed. The photocatalyst can accelerate the separation of photogenerated electron-hole pairs, increase the number of photocatalytic reaction sites, and have strong REDOX ability and charge transport ability. The degradation efficiency of MB is 3 times and 2 times of that of pure g-C3N4 and ZnFe2O4, respectively. Visible light (Vis)/ZnFe2O4/g-C3N4/sodium percarbonate (SPC) photo-Fenton system established under the synergistic effect of ZnFe2O4/g-C3N4 and SPC can continuously produce ·OH, ·O2− and h+. In half an hour, 93% of MB was degraded by Vis/ZnFe2O4/g-C3N4/SPC, and the degradation rate of MB was above 90% for 5 consecutive cycles. Through characterization and water treatment experiments, ZnFe2O4/g-C3N4 heterostructure nanocomposite photocatalyst has the characteristics of high efficiency photocatalytic oxidation activity, stability, superparamagnetism, easy separability and reusability, and can be reused continuously. Therefore, it is a promising photocatalyst in the field of wastewater treatment and a potential candidate material for the treatment of refractory organic pollutants.

Efficient electro catalytic performance of palladium nanoparticles assisted on bi-composite material (GRNPs-GCN) for electro chemical oxidation of methanol in alkaline media

This study reports a novel co-deposited catalyst which covalently coupled composite of Pd@ GRNPs-GCN for methanol electro-oxidation was investigated. The prepared nanocomposite material was further characterized through FTIR, XRD, SEM, and EDX analysis. The results showed that the Pd@GRNPs-GCN has stronger interaction, active specific area & rich content of pyridine & pyrrole nitrogen species which promotes the dispersion of PdNPs on GRNPs-GCN to present superior catalytic efficiency towards MOR. Moreover, the electrochemical analysis of cyclic voltammetry (CV), chronoamperometry (CA) & electro chemical impedance spectroscopy (EIS) proved that fabricated Pd@GRNPs-GCN electro catalyst showed significant catalytic activity, lesser oxidation potential & longevity for the electrochemical oxidation of methanol in alkali media. All these results revealed that the nanocomposite hybrid electro catalyst for feature endeavours in DMFCs (Direct methanol fuel cells) applications.

Toward maximizing the selectivity of diesel-like hydrocarbons from oleic acid hydrodeoxygenation using Ni/Co-Al2O3 embedded mesoporous silica nanocomposite catalysts: An experimental and DFT approach

The development of an effective hydrodeoxygenation (HDO) catalyst is crucial for controlling product selectivity and catalyst stability. In this study, we synthesized monometallic (Ni and Co), as well as a bimetallic, NiCo embedded mesoporous composite catalysts using a simple one-step method involving meso-macroporous silica, boehmite, nickel acetate, and cobalt acetate. The synthesized range of catalysts (5, 10, 15 wt% Ni, 10 wt% Co, 10 wt% NiCo) were thoroughly characterized by various techniques. The characterization results showed that the present method leads to the growth of nano-catalyst on porous silica surface (M−Al2O3/SiO2, M = Ni, Co, NiCo). These composites exhibited strong metal-support interaction, improved surface and texture properties and significant amount of weak to medium acid sites. The M−Al2O3/SiO2 composite catalysts demonstrated improved catalytic performance in the HDO of oleic acid. At temperature of 375 °C, the conversion trend of catalysts followed the order; 10NiCo-Al2O3/SiO2 (89%) > 10Ni-Al2O3/SiO2 (87%) > 10Co-Al2O3/SiO2 (85%) > 10Ni/SiO2 (81%). Moreover, the yield of C15-C18 hydrocarbons was substantially enhanced at moderate temperature compared to unmodified silica support. Time-on-stream experiments further confirmed the relative stability of the composite catalysts over a period of 20 h. Furthermore, density functional theory (DFT) ab initio calculations were performed where the adsorption of oleic acid on icosahedral monometallic M13 (M = Co or Ni) and bimetallic Ni2Co2 nanocluster deposited on γ-Al2O3 (110) support was investigated. The adsorption strength for the most stable conformations followed the order: Ni13/amorphous SiO2 >Ni2Co2/Al2O3 >Co13/Al2O3 >Ni13/Al2O3. Bader charge transfer analysis indicated higher charge transfer at the interfaces of γ-Al2O3Al2O3(110) supported catalysts compared to Ni13/amorphous SiO2 surface.

Development of nanostructured catalysts for catalytic oxidative water purification from organic impurities, including phenolic compounds

The purpose of this work was to create magnetic nanocatalysts that could be used for the oxidation of organic water pollutants – phenol and its derivatives – and to determine the physicochemical characteristics of the catalysts. The development of such active nanocomposite catalysts would solve the environmental problem in the Republic of Kazakhstan in the field of wastewater treatment from organic impurities, including phenols, and would also contribute to the subsequent creation of domestic production of oxygen-containing compounds, since almost the entire spectrum of oxygen-containing compounds for various industries is imported into the Republic. Nanosized magnetic composites based on Fe and Co were obtained by chemical deposition, in some cases, using polyethyleneimine and polyvinylpyrrolidone. It was shown that the interaction between nanoparticles and the polymer takes place in the case of a CoFe2O4 catalyst stabilized with polyvinylpyrrolidone or polyethyleneimine, which may indicate the efficient formation of nanocomposites. According to the IR study, for the CoFe2O4 nanocomposite stabilized with polyvinylpyrrolidone, the absorption bands at 735, 663, 649, 626 cm–1 are natural vibrations for the composite nanoparticles embedded in a polyvinylpyrrolidone matrix. The synthesized nanocomposites were tested in the oxidation of phenol with oxygen. The results demonstrate that the catalysts are promising both for the purification of industrial wastewater from phenol and for the synthesis of oxygen-containing compounds in the liquid phase under mild conditions.

Ag/g-C3N4 nanocomposite: Green fabrication and its application as a catalyst in the synthesis of new series of depsipeptides as biologically active compounds and investigation on their anti-breast cancer activity

In this study, we bring forward a green and novel eco-friendly strategy for the fabrication of Ag/g-C3N4 nanocomposite via a fast in-situ generation method using Ferula Gummosa extracts as both stabilizer and reducing agent. Ag/g-C3N4 nanocomposite was analyzed by Fourier transform infrared spectra (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX-MAP), and transmission electron microscopy (TEM). After procurement and characterization, the catalytic activity of the prepared reagent was surveyed in the synthesis of a new series of depsipeptides using aspirin/ketoprofen, cyclohexyl isocyanide, and aryl aldehydes at ambient temperature in EtOH/H2O as a green media. Taking into account the economic and environmental facets, the method bestows some advantages such as using plant extracts as green media for the preparation of Ag nanoparticles, simple work-up procedure, mild reaction conditions, short reaction times, and high yields of the products. Additionally, the Ag/g-C3N4 nanocomposite catalyst can be recycled effectually and reused several times without a substantial loss in reactivity.

Photoelectrocatalytic degradation of wastewater and simultaneous synthesis of NH3 on Fe-CNTs-supported octahedral Cu2O composite nanocatalysts

Fe-core carbon nanotubes (Fe-CNTs) were produced by vapor deposition using coal as a carbon source. Then, octahedral copper oxide nanoparticles (Cu2ONO) (prepared by solvent reduction method) were loaded on Fe-CNTs by hydrothermal method to prepare the composite catalyst Cu2ONO/Fe-CNTs. While characterizing (TEM, XRD, FTIR, XPS, N2-TPD, BET, etc.) the material structure, the performance of Cu2ONO/Fe-CNTs in photoelectrocatalytic (PEC) degradation of cotton pulp black liquor (CPBL an organic wastewater with high CODCr) and simultaneous synthesis of NH3 was studied. The PEC reaction was carried out in an H-type reactor. CPBL was oxidized at the anode to produce H+, CO2, H2O and other small molecules, where H+ passes through a proton exchange membrane and is reduced with N2 to produce NH3 at the cathode. After 4 h of reaction, the CODCr removal rate of CPBL in the anode chamber reached 95.42%, and the yield of NH3 in the cathode chamber reached 9.06 mmol L−1 cm−2. The dual purpose of synthesizing NH3 while degrading wastewater was achieved.

Exceptional catalytic effect of novel rGO-supported Ni-Nb nanocomposite on the hydrogen storage properties of MgH2

The design of an excellent active catalyst to improve the sluggish kinetic and thermodynamic properties of magnesium hydride (MgH2) remains a great challenge to achieve its practical application. In this study, a novel Ni-Nb/rGO nanocomposite catalyst was successfully prepared by one-spot hydrothermal and subsequent calcination methods. The novel Ni-Nb/rGO nanocomposite exhibits an exceptional catalytic effect on improving MgH2 sorption properties. Specifically, the onset desorption temperature of MgH2 + 10 wt% Ni-Nb/rGO composite is reduced to 198 °C, much lower than that of undoped MgH2 (330 °C). Interestingly, the composite can release 5.0, 5.9, and 6.0 wt% H2 within 10 min at 245, 260, and 275 °C, respectively. Furthermore, the dehydrogenated MgH2 + 10 wt% Ni-Nb/rGO composite starts to absorb hydrogen even at room temperature with approximate 2.75 wt% H2 uptake at 75 °C under 3 MPa H2 pressure within 30 min and exhibits excellent stability by maintaining 6.0 wt% hydrogen content after 20 cycles at 300 °C. Chou's model suggests that the de/hydrogenation kinetics of Ni-Nb/rGO-modified MgH2 switches from surface penetration model to diffusion model at lower temperatures. Additionally, the activation energies (Ea) for the de/hydrogenation of MgH2 + 10 wt% Ni-Nb/rGO are reduced to 57.8 kJ/mol and 33.9 kJ/mol, which are significantly lower than those of undoped MgH2. The work demonstrates that the addition of a novel ternary Ni-Nb/rGO catalyst is an effective strategy to not only boost the sorption kinetics of MgH2 but also maintain its cycling property.

Magnetically isolable Pd(0) nanoparticles supported on surface functionalized Fe3O4 for hydrogen generation via ammonia borane hydrolysis

AbstractPd(0) nanoparticles supported on surface functionalized magnetite (Fe3O4/SiO2‐NH2/HB@Pd) were prepared as catalyst for hydrolysis of ammonia borane (AB). The obtained magnetic nanocomposite material was seperated from the reaction media through a permanent magnet and characterized by FT‐IR, XRD, SEM‐EDX, TEM, ICP‐OES and XPS techniques. 100 mg Fe3O4/SiO2−NH2/HB@Pd nanocomposite with Pd metal content of 6.00±0.14 catalyzed the hydrolysis of 10 mM AB at 25 °C with 100 % yield. The presented work includes the effect of catalyst amount and temperature on the rate of the hydrolysis reaction of AB. As a result of the kinetic studies, the activation energy (Ea) for the Fe3O4/SiO2−NH2/HB@Pd catalyzed AB hydrolysis reaction was calculated as 34±1 kJ.mol−1, and the TOF value was calculated as 133 mol H2.(mol Pd(0).h)−1. The designed heterogenous magnetic nanocomposite catalyst demonstrated significant catalytic activity for AB hydrolysis reaction at 25 °C.

Research progress of MOFs/carbon nanocomposites on promoting ORR in microbial fuel cell cathodes.

With the rapid development of the economy, energy demand is more urgent. Microbial fuel cells (MFCs) have the advantages of non-toxic, safety, and environmental protection, and are considered the ideal choice for the next generation of energy storage equipment. However, the slow kinetics of oxygen reduction reaction (ORR) on MFC air cathodes and the high cost of traditional platinum (Pt) catalysts hinder their practical application, so there is a need to develop efficient, low-cost, and stable electrocatalysts as alternatives. Recently, metal-organic framework (MOFs) has attracted wide attention in electrocatalysis. Electrocatalysts prepared by the nanocomposite of MOFs and carbon nanomaterials have multiple advantages, such as adjustable chemical properties, high specific surface area, and good electrical conductivity, which have been proven to be a promising electrocatalytic material. In this paper, the latest research progress of metal-organic frames (MOFs) and carbon nanocomposites is reviewed, and the preparation methods and modification of MOFs and carbon nanofibers, carbon nanotubes, and graphene composites are introduced, respectively, as well as their applications in MFC cathode. Finally, the main prospects of MOFs/carbon nanocomposite catalysts are put forward.