Catalyst For Reduction Reaction Research Articles

Enhanced photocatalytic reduction of p-nitrophenol by polyvinylpyrrolidone-modified MOF/porous MgO composite heterostructures

Catalysts derived from Metal-Organic Frameworks (MOF) present a compelling blend of cost-effectiveness and superior performance in reduction reactions. In this study, polymer-decorated MOF-Cobalt (MOF-Co) was deposited onto porous magnesium oxide (MgO) layers, acquired through surface modification of AZ31 Mg alloy via plasma-assisted oxidation, with the aim of fabricating novel catalysts for reduction reactions. Herein, this synthesis involved the utilization of Cobalt-benzene dicarboxylic acid (Co-BDC), where cobalt ions served as metal nodes and 1,4-benzene dicarboxylic acid (H2BDC) functioned as an organic linker, with and without the presence of polyvinylpyrrolidone (PVP) as an active site enhancer. The morphology of the prepared catalysts was affected by several factors such as pH, hydrothermal treatment duration, PVP content, and the presence of a MgO layer. The optimal catalyst, designated as metal-organic frameworks-cobalt at 80 °C temperature and 1 h of hydrothermal treatment at pH 4 (MOF-Co 1.4), was synthesized on the MgO layer using a solution containing 1.7 g of PVP, H2BDC, and Co(NO₃)₂.6H₂O. The paper-like morphology of the MOF-Co 1.4 catalyst facilitated exceptional performance, efficiently degrading p-nitrophenol (p-NP) under visible light irradiation with an impressive 99.74 % efficiency within just 5 min of exposure, while also demonstrating stability over five successive cycles. ·O2− species was found to drive the reduction reaction to p-aminophenol, with harmless compounds as byproducts, while GC-MS analysis identified intermediates in the reduction of p-NP. Density functional theory (DFT) calculations suggested that H2BDC and PVP jointly provided multi-active sites, enabling effective contact with reactants and rapid electron transfer, thus playing a synergistic role in the catalytic reduction process. This study pioneers a novel method for designing efficient bulk catalysts, achieving high efficiency and stability in pollutant degradation with fast, low-energy fabrication.

Starch Sodium Octenylsuccinate as a New Type of Stabilizer in the Synthesis of Catalytically Active Gold Nanostructures.

Here, starch derivatives, i.e., sodium starch octenylsuccinate (OSA starch, hereinafter referred to as OSA), were employed as both reducing and stabilizing agents for the unique, inexpensive, and simple synthesis of gold nanoparticles (OSA-AuNPs) in an aqueous solution with gold salt. The obtained OSA-AuNPs were characterized by UV-vis spectrophotometry, transmission electron microscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The catalytic activity of the obtained gold colloids was studied in the reduction of organic dyes, including methylene blue (C.I. Basic Blue 9) and rhodamine B (C.I. Basic Violet 10), and food coloring, including tartrazine (E102) and azorubine (E122), by sodium borohydride. Moreover, OSA-AuNPs were utilized as signal amplifiers in surface-enhanced Raman spectroscopy. The obtained results confirmed that gold nanoparticles can be used as effective catalysts in reduction reactions of selected organic dyes, as well as signal enhancers in the SERS technique.

Facile Cu–MOF-derived Co3O4 mesoporous-structure as a cooperative catalyst for the reduction nitroarenes and dyes

The present study describes the environmentally friendly and cost-effective synthesis of magnetic, mesoporous structure-Co3O4 nanoparticles (m-Co3O4) utilizing almond peel as a biotemplate. This straightforward method yields a material with high surface area, as confirmed by various characterization techniques. Subsequently, the utilization of m-Co3O4, graphene oxide (GO), Cu(II)acetate (Cu), and asparagine enabled the successful synthesis of a novel magnetic MOF, namely GO–Cu–ASP–m-Co3O4 MOF. This catalyst revealed remarkable stability that could be easily recovered using a magnet for consecutive use without any significant decline in activity for eight cycles in nitro compound reduction and organic dye degradation reactions. Consequently, GO–Cu–ASP-m-Co3O4 MOF holds immense potential as a catalyst for reduction reactions, particularly in the production of valuable amines with high industrial value, as well as for the elimination of toxic-water pollutants such as organic dyes.

Structural Control Enables Catalytic and Electrocatalytic Activity of Porous Tetrametallic Nanorods.

Integrating more than one type of metal into a nanoparticle that has a well-defined morphology and composition expands the functionalities of nanocatalysts. For a metal core/porous multimetallic shell nanoparticle, the availability of catalytically active surface sites and molecular mass transport can be enhanced, and the multielemental synergy can facilitate intraparticle charge transport. In this work, a reliable and robust synthesis of such a functional tetrametallic nanoparticle type is presented, where a micro- and mesoporous PdPtIr shell is grown on Au nanorods. The effect of critical synthesis parameters, namely temperature and the addition of HCl are investigated on the hydrodynamic size of the micellar pore template as well as on the stability of the metal chloride complexes and various elemental analysis techniques prove composition of the porous multimetallic shell. Due to the synergistic properties, the tetrametallic nanorods possess extensive negative surface charge making them a promising catalyst in reduction reactions. Dye degradation as well as the conversion of p-nitrophenol to p-aminophenol is catalyzed by the supportless nanorods without light illumination. By depositing the particles onto conductive substrates, the nanostructured electrodes show promising electrocatalytic activity in ethanol oxidation reaction. The nanocatalyst presents excellent morphological stability during all the catalytic test reactions.

Cysteine and Ionic Liquid Modified Magnetic Nanoparticles Supported RuCu as a New Bimetallic Catalyst in Reduction Reactions

In this study, bimetallic RuCu supported on L-cysteine functionalized ionic liquid modified magnetic nanoparticles (Fe3O4@IL-Cys-RuCu) was successfully synthesized and characterized. This bimetallic nanocatalyst showed excellent activity in the reduction of 2,3, and 4-nitrophenol isomers and organic dyes as well as catalytic degradation of tetracycline (TC) at room temperature in water. Using this catalyst, complete reduction of nitrophenols was achieved within 9-16 min and degradation of organic dyes and tetracycline were accomplished within 7-4 and 30 minutes, respectively. The superior activity of bimetallic RuCu compared to similar Ru and Cu catalysts was proved and results indicated that the based on type of reaction, bimetallic catalyst was 2-33 times more efficient than the corresponding monometallic catalysts. This catalyst was recovered and recycled up to 14 times without decreasing in the catalytic activity and stability of the reused catalyst was confirmed by TEM, XRD and XPS.

Palladium nanoparticles supported on ionic liquid and glucosamine-modified magnetic iron oxide as a catalyst in reduction reactions

A magnetic nanocomposite comprising imidazolium ionic liquid and glucosamine is successfully synthesized and used for stabilization of Pd nanoparticles. This new material, Fe3O4@SiO2@IL/GA-Pd, is fully characterized and applied as a catalyst in the reduction of nitroaromatic compounds to desired amines at room temperature. Also, the reductive degradation of organic dyes such as methylene blue (MB), methyl orange (MO), and rhodamine B (RhB) is studied and compared with another previous publications. The survey of the stabilization of the palladium catalytic entities is described demonstrating the separation ability and recycling of them. In addition, TEM, XRD, and VSM analyses of the recycled catalyst confirmed its stability.

Experimental and theoretical investigation of high-entropy-alloy/support as a catalyst for reduction reactions

Control of chemical composition and incorporation of multiple metallic elements into a single metal nanoparticle (NP) in an alloyed or a phase-segregated state hold potential scientific merit; however, developing libraries of such structures using effective strategies is challenging owing to the thermodynamic immiscibility of repelling constituent metallic elements. Herein, we present a one-pot interfacial plasma–discharge-driven (IP-D) synthesis strategy for fabricating stable high-entropy-alloy (HEA) NPs exhibiting ultrasmall size on a porous support surface. Accordingly, an electric field was applied for 120 s to enhance the incorporation of multiple metallic elements (i.e., CuAgFe, CuAgNi, and CuAgNiFe) into ally HEA-NPs. Further, NPs were attached to a porous magnesium oxide surface via rapid cooling. With solar light as the sole energy input, the CuAgNiFe catalyst was investigated as a reusable and sustainable material exhibiting excellent catalytic performance (100% conversion and 99% selectivity within 1 min for a hydrogenation reaction) and consistent activity even after 20 cycles for a reduction reaction, considerably outperforming the majority of the conventional photocatalysts. Thus, the proposed strategy establishes a novel method for designing and synthesizing highly efficient and stable catalysts for the convertion of nitroarenes to anilines via chemical reduction.

Metal‐Free Catalytic Reduction of 4‐Nitrophenol to 4‐Aminophenol by sp3@sp2‐Hybridized Bucky Nanodiamond

As a new generation of metal‐free carbon catalyst, the sp3@sp2‐hybridized bucky nanodiamond (ND) is competitive even compared to the traditional metal catalysts in many oxidative reactions. However, the application of the carbon catalyst in reduction reaction is barely conducted and the mechanism of this kind of reaction is generally unknown. To develop a wider scope of carbon catalysts and achieve an industrial promising activity of the metal‐free catalyst, here a series of sp3@sp2‐hybridized bucky ND for catalyzing a model reduction reaction of 4‐nitrophenol to 4‐aminophenol is developed, in which a quite satisfying metal‐free catalytic performance (better than many metal catalysts) is obtained and the discipline of getting better activities for the reduction reaction is revealed. The oxygen functionality and sp3/sp2 hybridized carbon ratio are confirmed to be the important influential factors. The similarity of the carbon catalyzing the reduction and oxidation reactions might bring a uniform concept for redox reactions with carbon catalysts.

Osmium-catalyzed reduction processes

Catalytic reduction processes are of vital importance in organic chemistry. Numerous reactions catalyzed by palladium, rhodium, ruthenium, iridium and platinum complexes have been developed. Meanwhile, the use of osmium compounds as catalysts for reduction reactions has received surprisingly little attention, although they can effectively accelerate some processes. In some cases, osmium catalysts are superior to related ruthenium compounds both in activity of the catalytic system and in stability of the catalys <i>per se</i>. This review systematically summarizes reductive transformations catalyzed by organometallic osmium complexes. General trends in this research area followed in the literature are described and prospects in this field of chemistry are discussed. The hydrogen transfer and borrowing hydrogen reactions, hydrogenation, hydroformylation, reductive amination, and water-gas shift reactions are considered.<br> The bibliography includes 96 references

An insight on Biocathode Microbial Desalination Cell: Current challenges and prospects

Microbial Desalination Cell (MDC) is an emerging sustainable technology that offers the significant advantage of simultaneous electricity generation, water desalination, and pollutants removal such as chemical oxygen demand (COD), biological oxygen demand (BOD), total dissolved solids (TDS), color, etc. from industrial or domestic wastewater. The current MDC technology primarily utilizes conventional (chemical) cathode for maximum power output and desalination efficiency, which is unsustainable and toxic to the environment. Utilization of biocathode in MDC is economically, environmentally, and socially sustainable due to reduced operation cost, eco-friendliness, stability for long-run over chemical electrodes, and efficient pollutant removal from wastewater, which in turn creates a pollution-free environment for the society. In biocathode MDC, bacteria, yeast, fungi, or algae acts as a catalyst for reduction reaction by forming biofilm at the cathode, which avoids the use of expensive metal catalysts and eliminates the toxicity produced by the chemical cathodes. Microalgae as a biocathode has the ability to provide four times the dissolved oxygen concentration by photosynthesis than that obtained by pumping external air. Hence, power output is increased on using microalgae, and meanwhile, energy consumption is zero. Although there are exceptional benefits, biocathode is underutilized since research contribution towards the use of diverse microorganisms as biocathode is yet to be improved. This review gives an intelligible picture on the importance of biocathode over other cathodes, microbial community and materials used, other applications, and downside of biocathode in MDC.

Novel Two-Dimensional Conjugated Microporous Polymer Bearing Benzothiadiazole Unit as a Metal-Free Electro-And Photoactive Catalyst for Co2 Reduction Reaction

Novel Two-Dimensional Conjugated Microporous Polymer Bearing Benzothiadiazole Unit as a Metal-Free Electro-And Photoactive Catalyst for Co2 Reduction Reaction

Effects of different exposed crystal surfaces of CeO2 loaded on an MnO2/X catalyst for the NH3-SCR reaction

To study the effects of the loading of different exposed crystal surfaces of CeO2 on an MnO2/X catalyst for the NH3-selective catalytic reduction (SCR) reaction, Mn/X, Mn–CeNP/X, Mn–CeNC/X and Mn–CeNR/X catalysts were synthesized via a solid-state diffusion method.

The Rise of Manganese-Catalyzed Reduction Reactions

AbstractRecent developments in manganese-catalyzed reducing transformations—hydrosilylation, hydroboration, hydrogenation, and transfer hydrogenation—are reviewed herein. Over the past half a decade (i.e., 2016 to the present), more than 115 research publications have been reported in these fields. Novel organometallic compounds and new reduction transformations have been discovered and further developed. Significant challenges that had historically acted as barriers for the use of manganese catalysts in reduction reactions are slowly being broken down. This review will hopefully assist in developing this research area, by presenting a clear and concise overview of the catalyst structures and substrate transformations published so far.1 Introduction2 Hydrosilylation3 Hydroboration4 Hydrogenation5 Transfer Hydrogenation6 Conclusion and Perspective

Awn Stem-Derived High-Activity Free-Metal Porous Carbon for Oxidation Reduction.

Designing oxygen reduction reaction (ORR) catalysts with excellent performance has far-reaching significance. In this work, a high-activity biomass free-metal carbon catalyst with N and S co-doped was successfully prepared by using the KOH activated awn stem powder as the precursor with organic matter pore-forming doping technology, which is named TAAS. The content of pyridine nitrogen groups accounts for up to 36% of the total nitrogen content, and a rich pore structure is formed on the surface and inside, which are considered as the potential active centers of ORR. The results show that the specific surface area of TAAS reaches 191.04 m2/g, which effectively increases the active sites of the catalyst, and the initial potential and half slope potential are as high as 0.90 and 0.76 V vs. RHE, respectively. This study provides a low-cost, environmentally friendly and feasible strategy for the conversion of low-value agricultural and forestry wastes into high value-added products to promote sustainable development of energy and the environment.

An ultra-dispersive, nonprecious metal MOF\u2013FeZn catalyst with good oxygen reduction activity and favorable stability in acid

Development of the more stable nonprecious oxygen reduction reaction (ORR) catalyst is of great significance nowadays. Herein, a high-performance iron-doped integral uniform macrocyclic organic framework (MOF–FeZn) catalyst is synthesized through a combined hydrothermal and pyrolysis process, showing favorable ORR activity and stability in acid. This as-synthesized MOF–FeZn catalyst displays high porous and graphitic structures with sufficient catalytic active dopants of pyridinic N, Fe–N, pyrrolic N, graphitic N, making it a promising ORR candidate catalyst with high electrochemical stability. The onset potential, half-wave potential and limited diffusion current density of MOF–FeZn are 0.93 V @ 0.1 mA cm−2, 0.768 V@ 2.757 mA cm−2 and 5.5 mA cm−2, respectively, which are comparable to the state-of-the-art nonprecious catalyst and commercial Pt/C. ORR catalysis on MOF–FeZn follows the nearly four-electron path. What is more, MOF–FeZn can sustain the 10,000 cycles electrochemical potential cycling process in acid with the half-wave potential changed only 21 mV, superior to the reduction of 149 mV for Pt/C. The well-developed integral uniform structures, homogeneously dispersed carbides and nitrides protected by the highly graphitic carbon layers and the better agglomeration suppression of nanoparticles by the confined graphitic carbon layers on catalyst can significantly enhance the catalytic activity and stability of MOF–FeZn.

The structure–activity correlation of bifunctional MnO2 polymorphoric and MoS2-based heterostructures: a highly efficient, robust electrochemical water oxidation and reduction reaction catalyst in alkaline pH

Phase controlled heterostructure derived from polymorphic MnO2 and MoS2 emerged as an advanced electrocatalyst. The decreased average oxidation state and layered interaction within the heterostructure significantly monitored water splitting process.

Three-step method with self-sacrificial Co to prepare a uniform 5 nm-scale Pt catalyst for the oxygen reduction reaction

Simple and rapid preparation method for a highly dispersed and small-sized CoPt catalyst.

Plasmonic MoO2 embedded MoNi4 nanosheets prepared by NiMoO4 transformation for visible-light-enhanced 4-nitrophenol reduction.

Plasmonic hybrid catalysts have attracted great interest for the reduction of nitrobenzene waste to valuable aminobenzene, because they can use renewable solar energy to accelerate the catalytic reaction. However, the economical synthesis of non-precious plasmonic hybrid catalysts remains a big challenge. Herein we report the synthesis of plasmonic MoO2-embedded MoNi4 nanosheets (MoNi4-MoO2) by thermal annealing of NiMoO4 at 600 °C under a hydrogen atmosphere. The MoNi4-MoO2 hybrid catalysts retain strong plasmon absorption from MoO2 and demonstrate good catalytic activity from MoNi4 for 4-nitrophenol reduction in the dark. Under visible light irradiation, the excitation of MoO2 plasmon promotes the catalytic reaction further due to hot electron-induced increase of catalytic activity of MoNi4. In addition, the hybrid catalysts are relatively stable even under illumination reaction conditions.

Atomically Dispersed M-N-C Catalysts in Proton Exchange Membrane Fuel Cells: Recent Progress and Perspectives

The selection of oxygen reduction reaction (ORR) catalysts plays a key role in enhancing the performance of proton exchange membrane fuel cells (PEMFCs). To optimize the energy conversion technology in PEMFCs and improve the cost-effectiveness of ORR catalysts, atomically dispersed metal-nitrogen-carbon (M-N-C) catalyst is regarded as one of the most promising materials to replace Pt-based catalysts. In this review, we summarize the advantages of atomically dispersed M-N-C catalysts in both physical and chemical properties, including controllable dimensions, ease of accessibility, high surface area and excellent conductivity. Additionally, the unique merits of their cost-effectiveness are also described by a concise comparison with other ORR catalysts. Subsequently, some of its main synthesis methods are based on the most commonly used zeolitic imidazolate framework (ZIF) precursor. Several other precursors involve carbon, nitrogen, and one or more active transition metals (mainly iron or cobalt) are introduced briefly. Although there are a variety of synthesis methods, all these methods are in line with pyrolysis technology. Then, the recent advancements of atomically dispersed M-N-C catalysts related to their development and application of Fe-N-C, Mn-N-C, and Co-N-C catalysts are comprehensively described. Finally, based on some common M-N-C catalysts, many improvement ideas are also proposed. The focus is on how to control the negative reaction in Fe-N-C catalysts, improve the activity of Co-N-C catalysts and Mn-N-C catalysts, and find more suitable transition metal materials to prepare M-N-C catalysts.

Fabrication of Conjugated Porous Polymer Catalysts for Oxygen Reduction Reactions: A Bottom-Up Approach

The present study demonstrates the fabrication of a conjugated porous polymer (CPP-P2) through a Pd-catalyzed Suzuki–Miyaura poly-condensation reaction. 13C cross-polarization solid-state NMR and Fourier transform infrared (FTIR) spectroscopy were used to characterize CPP-P2. Pristine nitrogen-containing CPP was explored as a catalyst for the oxygen reduction reaction in 0.1 M KOH aqueous alkaline media. In the case of CPP-P2,the polymer oxygen reduction reaction occurs via a four-electron transfer mechanism. An understanding of the oxygen reduction at the molecular level and the role of molecular packing in the three-dimensional structure was proposed based on density functional theory (DFT) modeling.