Catalytic Reduction of 4-Nitrophenol: A Quantitative Assessment of the Role of Dissolved Oxygen in Determining the Induction Time

Aqueous Cathodic Exfoliation Strategy toward Solution-Processable and Phase-Preserved MoS2 Nanosheets for Energy Storage and Catalytic Applications

The production of MoS₂ nanosheets by electrochemical exfoliation routes holds great promise as a means to access this two-dimensional material in large quantities for different practical applications. However, the use of electrolytes based on synthetic organic salts and solvents, as well as issues related to the unwanted oxidation and/or phase transformation of the exfoliated nanosheets, constitute significant obstacles that hinder the industrial adoption of the electrochemical approach. Here, we introduce a safe and sustainable method for the cathodic delamination of MoS₂ that makes use of aqueous solutions of very simple and widely available salts, mainly KCl, as the electrolyte. Combined with an appropriate biomolecule-based solvent transfer protocol, such an electrolytic exfoliation route is shown to afford colloidally dispersed, oxide-free, and phase-preserved MoS₂ nanosheets of high structural quality in considerable yields. The mechanisms behind the efficient aqueous delamination of the bulk MoS₂ cathode are also discussed and rationalized on the basis of the penetration of hydrated cations from the electrolyte between its layers and the immediate reduction of the accompanying water molecules. An asymmetric supercapacitor assembled with a cathodic MoS₂ nanosheet-single walled carbon nanotube hybrid as the positive electrode and activated carbon as the negative electrode delivered energy densities (e.g., 26 W h kg^-1 at 750 W kg^-1 in 6 M KOH) that were competitive with those of other MoS₂-based asymmetric devices. When used as a catalyst for the reduction of nitroarenes, the present cathodically exfoliated nanosheets exhibited one of the highest activities reported so far with MoS₂ nanostructures, the origin of which is accounted for as well. Overall, by facilitating access to this two-dimensional material through a particularly simple, efficient, and cost-effective technique, these results should expedite the practical implementation of MoS₂ nanosheets in energy storage, catalysis, and beyond.

Reduction of nitroarenes catalyzed by microgel-stabilized silver nanoparticles

Poly(N-isopropylacrylamide-co-acrylamide) (PNA-BIS-2) microgels were synthesized by free radical precipitation polymerization in aqueous medium. Spherical Ag nanoparticles with diameter of 10-20 nm were fabricated inside the PNA-BIS-2 microgels by in-situ reduction of silver nitrate using sodium borohydride as reducing agent. The Ag nanoparticles- loaded hybrid microgels were characterized by Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Energy dispersive X-ray (EDX), Scanning transmission electron microscopy (STEM), Ultraviolet visible spectroscopy (UV Visible), Thermogravimetric analysis (TGA) and X-ray diffraction (XRD). Ag contents in the hybrid system were determined by inductively coupled plasma - optical emission spectrometry (ICP-OES). Various nitroarenes were successfully converted into their respective aromatic amines with good to excellent yields (ranging from 75% to 97%) under mild reaction conditions. The catalyst has ability to successfully convert substituted nitroarenes into desired products keeping many functionalities intact. The catalyst can be stored for long time without any sign of aggregation and can be used multiple times without any significant loss in its catalytic activity.

Carbon Supported Gold Nanoparticles for the Catalytic Reduction of 4-Nitrophenol

This work is a detailed study on how to optimize gold colloids preparation and their deposition to very different in nature carbon materials. The change of the continuous phase and its dielectric constant is used to assure the good dispersion of the hydrophilic/hydrophobic carbons and the successful transfer of the preformed small size colloids to their surface. The sintering behavior of the particles during the calcination step is also studied and the optimal conditions to reduce to a minimum the particle size increase during the protecting agent removal phase are found. The as prepared catalysts have been tested in a relevant reaction in the field of environmental catalysis such as the reduction of 4-nitrophenol leading to promising results. Overall, this work proposes an important methodology to follow when a carbonaceous material are selected as catalyst supports for green chemistry reactions.

Green synthesis of Au decorated CoFe2O4 nanoparticles for catalytic reduction of 4-nitrophenol and dimethylphenylsilane oxidation

Gold nanoparticles (Au NPs) have been widely employed in catalysis. Here, we report on the synthesis and catalytic evaluation of a hybrid material composed of Au NPs deposited at the surface of magnetic cobalt ferrite (CoFe2O4). Our reported approach enabled the synthesis of well-defined Au/CoFe2O4 NPs. The Au NPs were uniformly deposited at the surface of the support, displayed spherical shape, and were monodisperse in size. Their catalytic performance was investigated towards the reduction of 4-nitrophenol and the selective oxidation of dimethylphenylsilane to dimethylphenylsilanol. The material was active towards both transformations. In addition, the LSPR excitation in Au NPs could be employed to enhance the catalytic performance, which was demonstrated in the 4-nitrophenol reduction. Finally, the magnetic support allowed for the easy recovery and reuse of the Au/CoFe2O4 NPs. In this case, our data showed that no significant loss of performance took place even after 10 reaction cycles in the oxidation of dimethylphenylsilane to dimethylphenylsilanol. Overall, our results indicate that Au/CoFe2O4 are interesting systems for catalytic applications merging high performances, recovery and re-use, and enhancement of activities under solar light illumination.

Photocatalysis as an advanced reduction process (ARP): The reduction of 4-nitrophenol using titania nanotubes-ferrite nanocomposites

TiO₂ photocatalysis is an advanced process, employed worldwide for the oxidation of organic compounds, that leads to significant technological applications in the fields of health and environment. The use of the photocatalytic approach in reduction reactions seems very promising and can open new horizons for green chemistry synthesis. For this purpose, titanium dioxide nanotubes (TNTs) were developed in autoclave conditions using TiO₂ P25 as a precursor material. Based on these nanotubular substrates, TiO₂/CoFe₂O₄ (TCF) nanocomposites were further obtained by wet impregnation method. The materials were thoroughly characterized and their structural, textural, vibrational, optoelectronic and magnetic properties were determined. The composite materials combine absorbance in the visible optical range and high BET surface area values (˜100 m²/g), showing extremely high yield in the photocatalytic reduction of 4-nitrophenol (4-NP), exceeding 94% within short illumination time (only 35 min). The developed nanocomposites were successfully reused in consecutive photocatalytic experiments and were easily removed from the reaction medium using magnets. Both remarkable recycling ability and high-performance stability in the photocatalytic reduction of nitrophenol were observed, thus justifying the significant economic potential and industrial perspectives for this advanced reduction process.

Preparation of amine functionalized g-C3N4@H/SMOF NCs with visible light photocatalytic characteristic for 4-nitrophenol degradation from aqueous solution

At ambience temperature, a facile and large-scale sonochemical synthesis route was used to synthesize graphitic carbon nitride@[Ti₄C₂₄H₃₉N₃O₂₉] metal-organic framework nanocomposites (g-C₃N₄-X@^YTi-MIL125-NH₂ NCs, where X and Y stood for the weight percentages of g - C₃N₄ and the synthesis method of Ti-MIL125-NH₂, respectively) having 2-Amino-1,4-benzenedicarboxylic acid (2-ATA) ligand with amine functional free groups. The obtained NCs were characterized by FT-IR, PXRD, FE-SEM, BET, UV-DRS, PL, EIS, and zeta potential. Moreover, g-C₃N₄-X@^YTi-MIL125-NH₂ capability to eliminate 4-nitrophenol (4-NP) contaminant from water via visible light illumination was explored. Our synthesized NCs under a facile, green ultrasonic technique (i.e. g-C₃N₄-30@^STi-MIL125-NH₂) had a higher percentage of degradation than those from hydrothermal technique (i.e. g-C₃N₄-30@^HTi-MIL125-NH₂) with degradation percentages of 75% and 57%, respectively, which resulted in effective mass transfer and separation of photo - generated charge carriers. Additionally, this higher percentage of degradation could be attributed to the larger surface area and unique morphology of the ultrasonically synthesized particles with higher homogeneity and better and non-agglomerated distribution. Furthermore, excellent reusability and stability were observed for g-C₃N₄-30@^STi-MIL125-NH₂. We also explored the role of some scavengers in the degradation procedures to investigate the effect of active species. The experimental results were used to describe the suggested mechanism capability for improved photocatalysis.

Rapid Self-Assembly of Metal/Polymer Nanocomposite Particles as Nanoreactors and Their Kinetic Characterization

Self-assembled metal nanoparticle-polymer nanocomposite particles as nanoreactors are a promising approach for performing liquid phase reactions using water as a bulk solvent. In this work, we demonstrate rapid, scalable self-assembly of metal nanoparticle catalyst-polymer nanocomposite particles via Flash NanoPrecipitation. The catalyst loading and size of the nanocomposite particles can be tuned independently. Using nanocomposite particles as nanoreactors and the reduction of 4-nitrophenol as a model reaction, we study the fundamental interplay of reaction and diffusion. The induction time is affected by the sequence of reagent addition, time between additions, and reagent concentration. Combined, our experiments indicate the induction time is most influenced by diffusion of sodium borohydride. Following the induction time, scaling analysis and effective diffusivity measured using NMR indicate that the observed reaction rate are reaction- rather than diffusion-limited. Furthermore, the intrinsic kinetics are comparable to ligand-free gold nanoparticles. This result indicates that the polymer microenvironment does not de-activate or block the catalyst active sites.

Novel alginate/polyethyleneimine hydrogel adsorbent for cascaded removal and utilization of Cu2+ and Pb2+ ions

Heavy metal ion pollution leads to severe health risk to human beings. Herein, a natural and highly efficient sodium alginate (ALG)/polyethyleneimine (PEI) composite hydrogel was designed and fabricated for the removal of heavy metal ions from wastewater. The adsorption of heavy metal ions on the ALG based, 3D composite hydrogel were thoroughly investigated in this study. Furthermore, the in situ reduced metal nanoparticle-loaded ALG/PEI composite hydrogel provided us a sustainable utilization route of the heavy metal ion with a promising adsorption-catalysis ability. In general, this research will present an effective and practical paradigm for the cascaded treatment and recycling of heavy metal ions in wastewater.

Au–Cu–M (M = Pt, Pd, Ag) nanorods with enhanced catalytic efficiency by galvanic replacement reaction

This work reports a general wet-chemistry method to produce Au–Cu–X (X = Pt, Pd, and Ag) trimetallic nanorods using galvanic replacement reaction with Au–Cu nanorods as the templates.

Best practices for reporting nanocatalytic performance: lessons learned from nitroarene reduction as a model reaction

Absent explicit knowledge of catalyst loading, the apparent rate (k_app) is a totally meaningless measure of catalytic activity.

Controllable Synthesis and Catalytic Performance of Gold Nanoparticles with Cucurbit[n]urils (n = 5⁻8)

A series of gold nanoparticles (AuNPs) was prepared in situ with different cucurbit[n]urils (CB[n]s) in an alkaline aqueous solution. The nanoparticle sizes can be well controlled by CB[n]s (n = 5, 6, 7, 8) with different ring sizes. The packing densities of CB[5⁻8] and free surface area on AuNPs were determined. A direct relationship was found between the ring size and packing density of CB[n]s with respect to the AuNP-catalyzed reduction of 4-nitrophenol in the presence of NaBH₄. The larger particle size and higher surface coverage of bigger CB[n]-capped AuNPs significantly decreased the catalytic activity. Furthermore, this work could lead to new applications that utilize AuNPs under an overlayer of CB[n]s for catalysis, sensing, and drug delivery.

Light-Mediated Growth of Noble Metal Nanostructures (Au, Ag, Cu, Pt, Pd, Ru, Ir, Rh) From Micro- and Nanoscale ZnO Tetrapodal Backbones

Micro- and nanoscale ZnO tetrapods provide an attractive support for metallic nanostructures since they can be inexpensively produced using the flame transport method and nanoparticle synthesis schemes can take advantage of a coupled response facilitated by the formation of a semiconductor-metal interface. Here, we present a light-mediated solution-based growth mode capable of decorating the surface of ZnO tetrapods with nanostructures of gold, silver, copper, platinum, palladium, ruthenium, iridium, and rhodium. It involves two coupled reactions that are driven by the optical excitation of electron-hole pairs in the ZnO semiconductor by ultraviolet photons where the excited electrons are used to reduce aqueous metal ions onto the ZnO tetrapod as excited holes are scavenged from the surface. For the most part, the growth mode gives rise to nanoparticles with a roundish morphology that are uniformly distributed on the tetrapod surface. Larger structures with irregular shapes are, however, obtained for syntheses utilizing aqueous metal nitrates as opposed to chlorides, a result that suggests that the anion plays a role in shape determination. It is also demonstrated that changes to the molarity of the metal ion can influence the nanostructure nucleation rate. The catalytic activity of tetrapods decorated with each of the eight metals is assessed using the reduction of 4-nitrophenol by borohydride as a model reaction where it is shown that those decorated with Pd, Ag, and Rh are the most active.

In Situ Growth of Pd Nanosheets on g-C3 N4 Nanosheets with Well-Contacted Interface and Enhanced Catalytic Performance for 4-Nitrophenol Reduction

Loading novel metal nanosheets onto nanosheet support can improve their catalytic performance, but the morphological incompatibility makes it difficult to construct a well-contacted interface, which is of particular interest in supported catalysts. Herein, Pd nanosheets (Pd NSs) are supported onto graphitic carbon nitride nanosheets (CNNSs) with intimate face-to-face contact through an in situ growth method. This method overcomes the limitations of the morphological incompatibility and ensures the intimate interfacial contact between Pd NSs and CNNSs. The nitrogen-rich nature of CNNSs endows Pd NSs with abundant anchoring sites, which optimizes the electronic structure and improves the chemical and morphological stability of Pd NSs. The supported Pd NSs demonstrate high dispersion and exhibit largely enhanced activity toward the reduction of 4-nitrophenol. The concentration-normalized rate constant is up to 3052 min-1 g-1 L, which is 5.4 times higher than that obtained by unsupported Pd NSs. No obvious deactivation is observed after six runs of the recycling experiments. It is believed that the supported novel metal nanosheets with the intimately contacted interface may show promising applications in catalysis.

3D-macroporous chitosan-based scaffolds with in situ formed Pd and Pt nanoparticles for nitrophenol reduction

3D-macroporous chitosan-based scaffolds (cryogels) were produced via growth of metal-polymer coordinated complexes and electrostatic interactions between oppositely charged groups of chitosan and metal ions under subzero temperatures. A mechanism of reduction of noble metal complexes inside the cryogel walls by glutaraldehyde is proposed, which produces discrete and dispersed noble metal nanoparticles. 3D-macroporous scaffolds prepared under different conditions were characterised using TGA, FTIR, nitrogen adsorption, SEM, EDX and TEM, and the distribution of platinum nanoparticles (PtNPs) and palladium nanoparticles (PdNPs) in the material assessed. The catalytic activity of the in situ synthesised PdNPs, at 2.6, 12.5 and 21.0 μg total mass, respectively, was studied utilising a model system of 4-nitrophenol reduction. The kinetics of the reaction under different conditions (temperature, concentration of catalyst) were examined, and a decrease of catalytic activity was not observed over 17 treatment cycles. Increasing the temperature of the catalytic reaction from 10 to 22 and 35 °C by PdNPs supported within the cryogel increased the kinetic rate by 44 and 126%, respectively. Turnover number and turnover frequency of the PdNPs catalysts at room temperature were in the range 0.20-0.53 h^-1. The conversion degree of 4-nitrophenol at room temperature reached 98.9% (21.0 μg PdNPs). Significantly less mass of palladium nanoparticles (by 30-40 times) was needed compared to published data to obtain comparable rates of reduction of 4-nitrophenol.

Catalysis by Metallic Nanoparticles in Solution: Thermosensitive Microgels as Nanoreactors

Metallic nanoparticles have been used as catalysts for various reactions, and the huge literature on the subject is hard to overlook. In many applications, the nanoparticles must be affixed to a colloidal carrier for easy handling during catalysis. These “passive carriers” (e.g. dendrimers) serve for a controlled synthesis of the nanoparticles and prevent coagulation during catalysis. Recently, hybrids from nanoparticles and polymers have been developed that allow us to change the catalytic activity of the nanoparticles by external triggers. In particular, single nanoparticles embedded in a thermosensitive network made from poly(N-isopropylacrylamide) (PNIPAM) have become the most-studied examples of such hybrids: immersed in cold water, the PNIPAM network is hydrophilic and fully swollen. In this state, hydrophilic substrates can diffuse easily through the network, and react at the surface of the nanoparticles. Above the volume transition located at 32°C, the network becomes hydrophobic and shrinks. Now hydrophobic substrates will preferably diffuse through the network and react with other substrates in the reaction catalyzed by the enclosed nanoparticle. Such “active carriers”, may thus be viewed as true nanoreactors that open new ways for the use of nanoparticles in catalysis. In this review, we give a survey on recent work done on these hybrids and their application in catalysis. The aim of this review is threefold: we first review hybrid systems composed of nanoparticles and thermosensitive networks and compare these “active carriers” to other colloidal and polymeric carriers (e.g. dendrimers). In a second step we discuss the model reactions used to obtain precise kinetic data on the catalytic activity of nanoparticles in various carriers and environments. These kinetic data allow us to present a fully quantitative comparison of different nanoreactors. In a final section we shall present the salient points of recent efforts in the theoretical modeling of these nanoreactors. By accounting for the presence of a free-energy landscape for the reactants’ diffusive approach towards the catalytic nanoparticle, arising from solvent-reactant and polymeric shell-reactant interactions, these models are capable of explaining the emergence of all the important features observed so far in studies of nanoreactors. The present survey also suggests that such models may be used for the design of future carrier systems adapted to a given reaction and solvent.

Interfacial Phenomenon and Nanostructural Enhancements in Palladium Loaded Lanthanum Hydroxide Nanorods for Heterogeneous Catalytic Applications

Hydrogenation and cross-coupling reactions are of great importance for industrial applications and noble metal based catalysts are filling the void since the last few decades. However, the high cost of noble metals and poor recycling performance provides an opportunity for chemists to look for alternate options. Herein, we present the use of Lanthanum hydroxide as support for loading ultra-low amount of Pd for hydrogenation and cross-coupling reactions. Lanthanum hydroxide having controlled morphologies comprises exposed crystallographic facets which interact with small sized Pd NPs and shows versatile and effective catalytic performance. The reduction of 4-NP over Pd/La(OH)3 was achieved within very short time (45s) with a rate constant of 60 × 10⁻³ s⁻¹. The hydrogenation of styrene was also accomplished within 1 hour with much high TOF value (3260 h⁻¹). Moreover, the Suzuki cross-couplings of iodobenzene and phenyl boronic acid into biphenyl completed within 35 min with a TOF value of 389 h⁻¹. The strong interfacial electronic communication regulates electron density of catalytic sites and lowers energy for adsorption of reactant and subsequently conversion into products. Moreover, abundant hydroxyl groups on the surface of La(OH)3, large surface area, mono-dispersity and ultra-small size of Pd NPs also favors the efficient conversion of reactants.

Performance of Preformed Au/Cu Nanoclusters Deposited on MgO Powders in the Catalytic Reduction of 4-Nitrophenol in Solution

The deposition of preformed nanocluster beams onto suitable supports represents a new paradigm for the precise preparation of heterogeneous catalysts. The performance of the new materials must be validated in model catalytic reactions. It is shown that gold/copper (Au/Cu) nanoalloy clusters (nanoparticles) of variable composition, created by sputtering and gas phase condensation before deposition onto magnesium oxide powders, are highly active for the catalytic reduction of 4-nitrophenol in solution at room temperature. Au/Cu bimetallic clusters offer decreased catalyst cost compared with pure Au and the prospect of beneficial synergistic effects. Energy-dispersive X-ray spectroscopy coupled with aberration-corrected scanning transmission electron microscopy imaging confirms that the Au/Cu bimetallic clusters have an alloy structure with Au and Cu atoms randomly located. Reaction rate analysis shows that catalysts with approximately equal amounts of Au and Cu are much more active than Au-rich or Cu-rich clusters. Thus, the interplay between the Au and Cu atoms at the cluster surface appears to enhance the catalytic activity substantially, consistent with model density functional theory calculations of molecular binding energies. Moreover, the physically deposited clusters with Au/Cu ratio close to 1 show a 25-fold higher activity than an Au/Cu reference sample made by chemical impregnation.

Hemoglobin-driven iron-directed assembly of gold nanoparticles

The ability to form complex 3D architectures using nanoparticles (NPs) as the building blocks and complex macromolecules that direct these assemblies remains a challenging objective for nanotechnology. Here we report results in which the partial substitution of classical Turkevich citrate-capped gold NPs by a novel, heteroaromatic ligand (L) results in NPs able to form coordination-driven assemblies mediated by free or protein-bound iron ions. The morphology of these assemblies can be tuned depending on the source of iron. To prove the concept, classical citrate and novel NPs were reacted with iron-containing protein hemoglobin (Hb). To diminish the influence of possible electrostatic interactions of native Hb and gold NPs, the reaction was performed at the isoelectric point of Hb. Moreover, thiol groups of Hb were protected with p-quinone to exclude thiol–gold bond formation. As expected, citrate-capped gold NPs are well dispersed in functionalized Hb, while L-functionalized NPs form assemblies. The blue shift of the Soret band of the functionalized Hb, when reacted with novel NPs, unambiguously confirms the coordination of a NP-anchored heteroaromatic ligand with the heme moiety of Hb. Coarse-grained molecular dynamics of this system were performed to gain information about aggregation dynamics and kinetics of iron- and hemoglobin-templated assemblies of L–NPs. A multi-scale simulation approach was employed to extend this model to longer time scales. The application of this model towards novel coordination-based assemblies can become a powerful tool for the development of new nanomaterials.

The ability to form complex 3D architectures using nanoparticles as the building blocks and complex macromolecules that direct these assemblies remains a challenging objective for nanotechnology.

Ag–Au bimetallic nanocomposites stabilized with organic–inorganic hybrid microgels: synthesis and their regulated optical and catalytic properties

Ag–Au bimetallic nanocomposites stabilized with organic–inorganic hybrid microgels allowed the mass transfer of reactants to be controlled by temperature modulation.

Continuous synthesis of tuneable sized silver nanoparticles via a tandem seed-mediated method in coiled flow inverter reactors

Size control of metal nanoparticles is essential to achieve accurate adjustment of their unique chemical and physical properties.

Nanoscale Surface Curvature Effects on Ligand-Nanoparticle Interactions: A Plasmon-Enhanced Spectroscopic Study of Thiolated Ligand Adsorption, Desorption, and Exchange on Gold Nanoparticles

The interfacial adsorption, desorption, and exchange behaviors of thiolated ligands on nanotextured Au nanoparticle surfaces exhibit phenomenal site-to-site variations essentially dictated by the local surface curvatures, resulting in heterogeneous thermodynamic and kinetic profiles remarkably more sophisticated than those associated with the self-assembly of organothiol ligand monolayers on atomically flat Au surfaces. Here we use plasmon-enhanced Raman scattering as a spectroscopic tool combining time-resolving and molecular fingerprinting capabilities to quantitatively correlate the ligand dynamics with detailed molecular structures in real time under a diverse set of ligand adsorption, desorption, and exchange conditions at both equilibrium and nonequilibrium states, which enables us to delineate the effects of nanoscale surface curvature on the binding affinity, cooperativity, structural ordering, and the adsorption/desorption/exchange kinetics of organothiol ligands on colloidal Au nanoparticles. This work provides mechanistic insights on the key thermodynamic, kinetic, and geometric factors underpinning the surface curvature-dependent interfacial ligand behaviors, which serve as a central knowledge framework guiding the site-selective incorporation of desired surface functionalities into individual metallic nanoparticles for specific applications.

Unusual Hollow Al2O3 Nanofibers with Loofah-Like Skins: Intriguing Catalyst Supports for Thermal Stabilization of Pt Nanocrystals

Recently, hollow nanofibers could be fabricated by coaxis electrospinning method or template method. However, they are limited to applications because of the hardship in actual preparation. In this work, hollow γ-Al₂O₃ nanofibers with loofah-like skins were first fabricated by using a single spinneret during electrospinning. These intriguing nanofibers were explored as new Pt supports with excellently sinter-resistant performance up to 500 °C, attributed to the unique loofah-like surface of γ-Al₂O₃ nanofibers and the strong metal-support interactions between Pt and γ-Al₂O₃. When applied in the catalytic reduction of p-nitrophenol, the Pt/γ-Al₂O₃ calcined at 500 °C exhibited 4-times higher reaction rate constant (6.8 s^-1·mg^-1) over free Pt nanocrystals.

One-step catalytic reduction of 4-nitrophenol through the direct injection of metal salts into oxygen-depleted reactants

The one-step catalytic reduction of 4-nitrophenol using nanoparticles derived from the injection of metal salts leads to benchmark-setting turnover frequencies.

Graphene sheets manipulated the thermal-stability of ultrasmall Pt nanoparticles supported on porous Fe2O3nanocrystals against sintering

This study reports a new sinter-resistant catalyst system, consisting of Pt nanoparticles on Fe₂O₃rhombohedrons isolated by wrinkled graphene sheets.

Copper and silver nanoparticles stabilized by bistriazole-based dendritic amphiphile micelles for 4-nitrophenol reduction

Copper and silver nanoparticles stabilized on dendritic amphiphiles catalyzed 4-nitrophenol reduction at the ppm level, with particle size influencing catalytic efficiency.