Dispersed Cu₂O octahedrons on h-BN nanosheets for p-nitrophenol reduction

Boosting catalytic activity of metal nanoparticles for 4-nitrophenol reduction: Modification of metal naoparticles with poly(diallyldimethylammonium chloride)

Most of the previously reported studies have focused on the change in the size, morphology, and composition of metal nanocatalysts for improving their catalytic activity. Herein, we report poly(diallyldimethylammonium chloride) [PDDA]-stabilized nanoparticles (NPs) of platinum (Pt) and palladium (Pd) as highly active and efficient catalysts for hydrogenation of 4-nitrophenol (4-NP) in the presence of NaBH4. PDDA-stabilized Pt and Pd NPs possessed similar particle size and same facet with citrate-capped Pt and Pd NPs, making this study to investigate the inter-relationship between catalytic activity and surface ligand without the consideration of the effects of particle size and facet. Compared to citrate-capped Pt and Pd NPs, PDDA-stabilized Pt and Pd NPs exhibited excellent pH and salt stability. PDDA could serve as an electron acceptor for metal NPs to produce the net positive charges on the metal surface, which provide strong electrostatic attraction with negatively charged nitrophenolate and borohydride ions. The activity parameter and rate constant of PDDA-stabilized metal NPs were higher than those of citrate-capped metal NPs. Compared to the previously reported Pd nanomaterials for the catalysis of NaBH4-mediated reduction of 4-NP, PDDA-stabilized Pd NPs exhibited the extremely high activity parameter (195s^-1g^-1) and provided excellent scalability and reusability.

Photo-reduced Cu/CuO nanoclusters on TiO2 nanotube arrays as highly efficient and reusable catalyst

Non-noble metal nanoparticles are becoming more and more important in catalysis recently. Cu/CuO nanoclusters on highly ordered TiO₂ nanotube arrays are successfully developed by a surfactant-free photoreduction method. This non-noble metal Cu/CuO-TiO₂ catalyst exhibits excellent catalytic activity and stability for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with the presence of sodium borohydride (NaBH₄). The rate constant of this low-cost Cu/CuO based catalyst is even higher than that of the noble metal nanoparticles decorated on the same TiO₂ substrate. The conversion efficiency remains almost unchanged after 7 cycles of recycling. The recycle process of this Cu/CuO-TiO₂ catalyst supported by Ti foil is very simple and convenient compared with that of the common powder catalysts. This catalyst also exhibited great catalytic activity to other organic dyes, such as methylene blue (MB), rhodamine B (RhB) and methyl orange (MO). This highly efficient, low-cost and easily reusable Cu/CuO-TiO₂ catalyst is expected to be of great potential in catalysis in the future.

One-step synthesis of magnetically recyclable Co@BN core–shell nanocatalysts for catalytic reduction of nitroarenes

The possible mechanism for Co@BN catalyzed 4-nitrophenol reduction in the presence of NaBH₄. Moreover, the 13.6 wt% Co@BN core–shell nanoparticles exhibited the excellent catalytic activity in hydrogenation of nitroaromatic compounds.

Investigating the role of MoS2/reduced graphene oxide as cocatalyst on Cu2O activity in catalytic and photocatalytic reactions

Synergistic effect of MoS₂/rGO as cocatalyst on Cu₂O catalytic and photocatalytic activity.

Phosphomolybdic acid immobilized on ionic liquid-modified hexagonal boron nitride for oxidative desulfurization of fuel

An ionic liquid modified hexagonal boron nitride was developed for preparation of a supported catalyst with enhanced stability and excellent catalytic performance in catalytic oxidative desulfurization.

Design of 3D WO3/h-BN nanocomposites for efficient visible-light-driven photocatalysis

3D WO₃ nanoparticle/h-BN nanosheet composites (WO₃/BN) have been designed and fabricated by a simple in situ one-step calcination method.

Sucrose-mediated mechanical exfoliation of graphite: a green method for the large scale production of graphene and its application in catalytic reduction of 4-nitrophenol

A simple and green method for the large scale production of graphene by ball-milling of graphite with sucrose is exploited here.

Facile growth of Cu2O hollow cubes on reduced graphene oxide with remarkable electrocatalytic performance for non-enzymatic glucose detection

A facile and eco-friendly strategy was developed to grow highly dispersed Cu₂O hollow nanocubes on RGO sheets, which exhibit excellent electrocatalytic activity for glucose oxidation.

Microwave-assisted rapid synthesis of graphene-analogue hexagonal boron nitride (h-BN) nanosheets and their application for the ultrafast and selective adsorption of cationic dyes from aqueous solutions

Graphene-analogue hexagonal boron nitride (h-BN) nanosheets are successfully synthesizedviaa facile and fast microwave-assisted method in 10 min and used as a novel adsorbent for the ultrafast removal of cationic organic dyes in aqueous solution.

Morphology tuning of assembled Au–Cu nicotinate rings by ligand coordination and their use as efficient catalysts

In this work, cyclic annular Au–Cu nicotinates were synthesized through a facile one-pot method.

Highly efficient noble metal free copper nickel oxysulfide nanoparticles for catalytic reduction of 4-nitrophenol, methyl blue, and rhodamine-B organic pollutants

Novel and noble metal-free copper nickel oxysulfide nanoparticles have been successfully fabricated by using a simple, cost-effective, and eco-friendly solution-based approach, with copper oxysulfide as a comparative.

Impact of Covalent Functionalization on the Aqueous Processability, Catalytic Activity, and Biocompatibility of Chemically Exfoliated MoS2 Nanosheets

Chemically exfoliated MoS₂ (ce-MoS₂) has emerged in recent years as an attractive two-dimensional material for use in relevant technological applications, but fully exploiting its potential and versatility will most probably require the deployment of appropriate chemical modification strategies. Here, we demonstrate that extensive covalent functionalization of ce-MoS₂ nanosheets with acetic acid groups (∼0.4 groups grafted per MoS₂ unit) based on the organoiodide chemistry brings a number of benefits in terms of their processability and functionality. Specifically, the acetic acid-functionalized nanosheets were furnished with long-term (>6 months) colloidal stability in aqueous medium at relatively high concentrations, exhibited a markedly improved temporal retention of catalytic activity toward the reduction of nitroarenes, and could be more effectively coupled with silver nanoparticles to form hybrid nanostructures. Furthermore, in vitro cell proliferation tests carried out with murine fibroblasts suggested that the chemical derivatization had a positive effect on the biocompatibility of ce-MoS₂. A hydrothermal annealing procedure was also implemented to promote the structural conversion of the functionalized nanosheets from the 1T phase that was induced during the chemical exfoliation step to the original 2H phase of the starting bulk material, while retaining at the same time the aqueous colloidal stability afforded by the presence of the acetic acid groups. Overall, by highlighting the benefits of this type of chemical derivatization, the present work should contribute to strengthen the position of ce-MoS₂ as a two-dimensional material of significant practical utility.

Hydrogenation of nitroarenes into aromatic amines over Ag@BCN colloidal catalysts

The present work reports that two-dimension layered ternary boron carbon nitrogen nanosheets can serve as good carriers to support and disperse noble metal nanoparticles. The Ag@BCN colloids have thus been prepared by attaching Ag nanoparticles on the surfaces of BCN nanosheets. The detailed structures of the Ag@BCN samples were investigated by X-ray diffraction, transmission electron microscopy, atomic force microscope, infrared, and X-ray photoelectron spectroscopy. It is found that the surface NH groups of BCN nanosheets are beneficial for the attachment of Ag nanopaprticles. Compared with the conventional organic capping compounds, the two dimensional planar BCN nanosheets endow the attached nanoparticle with the high active surfaces. Moreover, the hydrogenation of nitroarenes into the corresponding aromatic amines can be highly achieved over Ag@BCN colloids by NaBH4. In particular, the apparent activation energy of the conversion reaction of p-nitroaniline to p-phenylenediamine was found to be 76.0kJ/mol over the Ag@BCN colloids with 3wt% Ag content. Our results may provide a new approach for the design noble metal based composites and find the practical application for the hydrogenation of nitroarenes.

Hexagonal boron nitride nanoplates as emerging biological nanovectors and their potential applications in biomedicine

The application of nanomaterials in the biological and medical areas has attracted great attention. Cytotoxicity, stability and solubility are the prerequisites for a nanomaterial to be considered for application in the field of biomedicine. Here, we suggest a simple method to produce highly dispersed water-soluble ultrathin h-BN nanoplates whose size measures ca. 30-60 nm in diameter and 1.6 nm in thickness. Moreover, we demonstrate that h-BN nanoplates can act as a reliable biological nanovector to carry proteins by cross-linking immobilization. Furthermore, the biocompatibility of h-BN nanoplates has also been explored via an apoptosis assay. In addition, a successful attempt has been made to investigate the potency of h-BN nanoplates as an immunostimulating adjuvant in a mouse immunization experiment. Preliminary results show that the level of antibody response stimulated by an antigen protein (bovine serum albumin) linked with h-BN is ca. 4 times higher than that by the antigen protein alone. This work gives evidence that water-soluble h-BN nanoplates are of high biocompatibility and low reactogenicity and therefore they can serve as an excellent biomedical platform for nanoparticle-biomolecular interactions. They preserve and even enhance the bioacitivities of the cross-linked antigen proteins, which strongly suggests their use in nanoparticle vaccine design.

Physico-Chemical Condition Optimization during Biosynthesis lead to development of Improved and Catalytically Efficient Gold Nano Particles

Biosynthesis of nanoparticles has gained great attention in making the process cost-effective and eco-friendly, but there are limited reports which describe the interdependency of physical parameters for tailoring the dimension and geometry of nanoparticles during biological synthesis. In the present study, gold nanoparticles (GNPs) of various shapes and sizes were obtained by modulating different physical parameters using Trichoderma viride filtrate. The particles were characterized on the basis of visual observation, dynamic light scattering, UV-visible spectroscopy, transmission electron microscopy, fourier transform infrared spectroscopy, and X ray diffraction. While the size varied from 2-500 nm, the shapes obtained were nanospheres, nanotriangles, nanopentagons, nanohexagons, and nanosheets. Changing the parameters such as pH, temperature, time, substrate, and culture filtrate concentration influenced the size and geometry of nanoparticles. Catalytic activity of the biosynthesized GNP was evaluated by UV-visible spectroscopy and confirmed by gas chromatography-mass spectrometric analysis for the conversion of 4-nitrophenol into 4-aminophenol which was strongly influenced by their structure and dimension. Common practices for biodegradation are traditional, expensive, require large amount of raw material, and time taking. Controlling shapes and sizes of nanoparticles could revolutionize the process of biodegradation that can remove all the hurdles in current scenario.

One-step synthesis of hollow porous gold nanoparticles with tunable particle size for the reduction of 4-nitrophenol

Hollow porous gold nanoparticles (HPGNPs) were synthesized via a one-step solution phase method at ambient temperature. The particle size, ranging from 80nm to 350nm, was easily controlled by changing the concentration of HAuCl4. The morphology and the structure of the as-prepared HPGNPs were investigated by SEM, TEM, HRTEM and XPS. Langmuir isotherm analysis yielded values of 8973m(2)/g for the outer surface area and 58724m(2)/g for the inner surface area for the 80nm HPGNPs. Due to a special hollow porous nanostructure, the HPGNPs exhibited superior catalytic activity and stability for the reduction of 4-nitrophenol (4-NP). No significant inactivation of the 80nm HPGNPs was observed, even after recycling for six cycles or storing for more than 1 month. Due to these excellent properties, it is expected that HPGNPs can be used in such applications as water pollutant removal and environmental remediation.

A ternary Cu2O-Cu-CuO nanocomposite: a catalyst with intriguing activity

In this work, the syntheses of Cu2O as well as Cu(0) nanoparticle catalysts are presented. Copper acetate monohydrate produced two distinctly different catalyst particles with varying concentrations of hydrazine hydrate at room temperature without using any surfactant or support. Then both of them were employed separately for 4-nitrophenol reduction in aqueous solution in the presence of sodium borohydride at room temperature. To our surprise, it was noticed that the catalytic activity of Cu2O was much higher than that of the metal Cu(0) nanoparticles. We have confirmed the reason for the exceptionally high catalytic activity of cuprous oxide nanoparticles over other noble metal nanoparticles for 4-nitrophenol reduction. A plausible mechanism has been reported. The unusual activity of Cu2O nanoparticles in the reduction reaction has been observed because of the in situ generated ternary nanocomposite, Cu2O-Cu-CuO, which rapidly relays electrons and acts as a better catalyst. In this ternary composite, highly active in situ generated Cu(0) is proved to be responsible for the hydride transfer reaction. The mechanism of 4-nitrophenol reduction has been established from supporting TEM studies. To further support our proposition, we have prepared a compositionally similar Cu2O-Cu-CuO nanocomposite using Cu2O and sodium borohydride which however displayed lower rate of reduction than that of the in situ produced ternary nanocomposite. The evolution of isolated Cu(0) nanoparticles for 4-nitrophenol reduction from Cu2O under surfactant-free condition has also been taken into consideration. The synthetic procedures of cuprous oxide as well as its catalytic activity in the reduction of 4-nitrophenol are very convenient, fast, cost-effective, and easily operable in aqueous medium and were followed spectrophotometrically. Additionally, the Cu2O-catalyzed 4-nitrophenol reduction methodology was extended further to the reduction of electronically diverse nitroarenes. This concise catalytic process in aqueous medium at room temperature revealed an unprecedented catalytic performance which would draw attention across the whole research community.

Shape-controlled synthesis of 3D copper nicotinate hollow microstructures and their catalytic properties

View of the process of preparation and catalysis of Cu hollow microstructures.

Mineralization of perfluorooctanesulfonate (PFOS) and perfluorodecanoate (PFDA) from aqueous solution by porous hexagonal boron nitride: adsorption followed by simultaneous thermal decomposition and regeneration

Some poly- and perfluoroalkyl substances (PFASs) are of global concern due to their toxicity, high persistency, bioaccumulation, and worldwide occurrence.

Graphene-analogue BN-modified microspherical BiOI photocatalysts driven by visible light

3D hierarchical microspherical BN/BiOI composites showed significantly enhanced photocatalytic activity in the degradation of Rhodamine B, methylene blue and 4-chlorophenol.

A two-oxide nanodiode system made of double-layered p-type Ag2O@n-type TiO2 for rapid reduction of 4-nitrophenol

The mechanism for the reduction reaction of 4-nitrophenol to 4-aminophenol in the presence of a SiO₂/Ag₂O@TiO₂ composite catalyst.

A template-free solvent-mediated synthesis of high surface area boron nitride nanosheets for aerobic oxidative desulfurization

Hexagonal BN nanosheets with high surface area are developed via methanol-mediated synthesis, presenting outstanding catalytic performance in aerobic oxidative desulfurization.

Heterogenization of homogenous oxidative desulfurization reaction on graphene-like boron nitride with a peroxomolybdate ionic liquid

Heterogenization of homogenous oxidative desulfurization reaction on graphene-like BN with a novel peroxomolybdate ionic liquid.

The release of hydrogen from ammonia borane over copper/hexagonal boron nitride composites

Facile solution-phase synthesis of copper nanoparticles dispersed on h-BN via a solvothermal method is proposed for hydrolytic dehydrogenation of ammonia borane.

An enzyme–copper nanoparticle hybrid catalyst prepared from disassembly of an enzyme–inorganic nanocrystal three-dimensional nanostructure

Enzyme–copper nanoparticle hybrid catalysts were prepared with highly retained enzymatic and Cu-catalytic activities, enabling the chemo-enzymatic cascade reactions.

A new approach for crystallization of copper(II) oxide hollow nanostructures with superior catalytic and magnetic response

We report the synthesis of copper(II) oxide hollow nanostructures at ambient pressure and close to room temperature by applying the soft templating effect provided by the confinement of droplets in miniemulsion systems. Particle growth can be explained by considering a mechanism that involves both diffusion and reaction control. The catalytic reduction of p-nitrophenol in aqueous media is used as a model reaction to prove the catalytic activity of the materials: the synthesized hollow structures show nearly 100 times higher rate constants than solid CuO microspheres. The kinetic behavior and the order of the reduction reaction change due to the increase of the surface area of the hollow structures. The synthesis also leads to modification of physical properties such as magnetism.

Boron nitride encapsulated copper nanoparticles: a facile one-step synthesis and their effect on thermal decomposition of ammonium perchlorate

Reactivity is of great importance for metal nanoparticles used as catalysts, biomaterials and advanced sensors, but seeking for high reactivity seems to be conflict with high chemical stability required for metal nanoparticles. There is a subtle balance between reactivity and stability. This could be reached for colloidal metal nanoparticles using organic capping reagents, whereas it is challenging for powder metal nanoparticles. Here, we developed an alternative approach to encapsulate copper nanoparticles with a chemical inertness material—hexagonal boron nitride. The wrapped copper nanoparticles not only exhibit high oxidation resistance under air atmosphere, but also keep excellent promoting effect on thermal decomposition of ammonium perchlorate. This approach opens the way to design metal nanoparticles with both high stability and reactivity for nanocatalysts and their technological application.

Nitroarene reduction: a trusted model reaction to test nanoparticle catalysts

Nitrophenol reduction to aminophenol with a reducing agent is conveniently carried out in aqueous medium mainly with a metal or metal oxide catalyst. This reduction is presently considered as a benchmark reaction to test a catalyst nanoparticle. Thousands of original reports have enriched this field of nanoparticle catalyzed reaction. Synthesis of different metal and metal oxide nanoparticles and their composites along with their role as catalysts for nitrophenol reduction with varying reducing agents have been elucidated here. The progress of the reaction is conveniently monitored by UV-visible spectrophotometry and hence it becomes a universally accepted model reaction. In this review we have discussed the reaction kinetics considering its elegance and importance enlightening the long known Langmuir-Hinshelwood mechanism and Eley-Rideal mechanism at length, along with a few other mechanisms recently reported. A brief description of the synthetic procedures of various nanoparticles and their respective catalytic behaviour towards nitroarene reduction has also been accounted here.

Synergetic catalytic effect of Cu2-xSe nanoparticles and reduced graphene oxide coembedded in electrospun nanofibers for the reduction of a typical refractory organic compound

A new heterogeneous catalytic composite composed of nonstoichiometric Cu2-xSe nanoparticles (NPs) with high copper deficiency and graphene oxide (GO) is prepared by coembedding in electrospun nanofibers of a poly(vinylpyrrolidone) (PVP) support, wherein GO in the nanofibers is converted into reduced GO (rGO) via heat treatment. The as-prepared composite Cu2-xSe/rGO/PVP nanofibers have demonstrated superior catalytic activity toward the reduction of a refractory organic compound by taking 4-nitrophenol (4-NP) as an example. In the presence of NaBH4, the Cu2-xSe/rGO/PVP nanofibers display a synergetic effect between Cu2-xSe and rGO in PVP nanofibers compared to their independent components or corresponding nanofibers. Furthermore, the Cu2-xSe/rGO/PVP nanofibers exhibit a favorable water-stable property via heat treatment to solidify the hydrophilic PVP matrix, which makes the composite display good reusability, stability in aqueous solution, and separability from a water medium. This work not only presents a direct, convenient, and effective approach to doping semiconductor nanomaterials into polymer nanofibers but also provides fundamental routes for further investigations about the synergetic effect between different materials based on the platform of electrospun nanofibers.

Synthesis and characterization of BN/Bi2WO6 composite photocatalysts with enhanced visible-light photocatalytic activity

Bi₂WO₆ modified with few-layer BN was synthesized by an impregnation method. The as-prepared BN/Bi₂WO₆ photocatalysts exhibited a higher photocatalytic activity for the degradation of Rhodamine B (RhB) than the pure Bi₂WO₆.

Dispersed SnO2 nanoparticles on MoS2 nanosheets for superior gas-sensing performances to ethanol

Novel composites with superior gas-sensing performance were successfully obtained by dispersing SnO₂ nanoparticles on the surfaces of MoS₂ nanosheets.

Carbon monoxide interactions with pure and doped B11XN12 (X = Mg, Ge, Ga) nano-clusters: a theoretical study

The influence of CO adsorption on the electronic and optical properties of the B₁₁XN₁₂ nano-cluster has been studied by DFT calculations.

Graphene-analogue boron nitride/Ag3PO4 composite for efficient visible-light-driven photocatalysis

Graphene-analogue BN modified Ag₃PO₄ photocatalysts were successfully prepared. In the presence of the BN, it could effectively enhance the photoactivity and stability of Ag₃PO₄.