Search Results (95)

Developments of nanostructured materials have a significant impact in various areas, such as energy technology and biomedical use. Examples include solar cells, energy management, environmental control, bioprobes, tissue engineering, biological marking, cancer diagnosis, therapy, and drug delivery. Currently, researchers are designing multifunctional nanodrugs that combine in vivo imaging (using fluorescent nanomaterials) with targeted drug delivery, aiming to maximize therapeutic efficacy while minimizing toxicity. These fascinating nanoscale “magic bullets” should be available in the near future. Inorganic nanovehicles are flexible carriers to deliver drugs to their biological targets. Most commonly, mesoporous nanostructured silica, carbon nanotubes, gold, and iron oxide nanoparticles have been thoroughly studied in recent years. Opposite to polymeric and lipid nanostructured materials, inorganic nanomaterial drug carriers are unique because they have shown astonishing theranostic (therapy and diagnostics) effects, expressing an undeniable part of future use in medicine. This review summarizes research from development to the most recent discoveries in the field of nanostructured materials and their applications in drug delivery, including promising metal-based complexes, platinum, palladium, ruthenium, titanium, and tin, to tumor cells and possible use in theranostics. Full article

For PEM fuel cell operation, high-purity hydrogen gas containing only trace amounts of carbon monoxide is a prerequisite. The water–gas shift reaction (WGSR) is an industrially applied mature operation mode to convert CO with H₂O into CO₂ (making it easy to separate, if necessary) and H₂. Since the WGS reaction is an exothermic equilibrium reaction, low temperatures (below 200 °C) lead to full CO conversion. Thus, highly active ultra-low-temperature WGSR catalysts have to be applied. A homogeneous Ru SILP (supported ionic liquid phase) catalyst based on the precursor complex [Ru(CO)₃Cl₂]₂ has been identified to operate at such low temperature levels. However, in a hydrogen rich atmosphere, transition metal complexes are prone to form nanoparticles (NPs) when dissolved in ionic liquids (ILs). In this article, the behavior of an anionic SILP WGSR catalyst, i.e., [Ru(CO)₃Cl₃]⁻ dissolved in [BMMIM]Cl, in an H₂-rich CO environment is described. The data reveal that during the WGSR, Ru nanoparticles form in the catalyst when very low CO concentrations are reached. The Ru NPs formation has been confirmed by transmission electron microscopy imaging and X-ray diffraction (XRD). Full article

Chemical recycling of plastic waste, especially polyolefins, into valuable liquid fuels is of considerable significance to address the serious issues raised by their threat on environmental and human health. Nevertheless, the construction of efficient and economically viable catalytic systems remains a significant hurdle. Herein, we developed an efficient bifunctional catalyst system comprising γ-Al₂O₃-supported ruthenium nanoparticles (Ru/γ-Al₂O₃) and β-zeolite for the conversion of polyolefins into gasoline-range hydrocarbons. A yield of C_5–12 paraffins up to 73.4% can be obtained with polyethene as the reactant at 250 °C in hydrogen. The Ru sites primarily activate the initial cleavage of C–H bonds of polymer towards the formation of olefin intermediates, which subsequently go through further cracking and isomerization over the acid sites in β-zeolite. Employing in situ infrared spectroscopy and probe–molecule model reactions, our investigation reveals that the optimized proportion and spatial distribution of the dual catalytic sites are pivotal in the tandem conversion process. This optimization synergistically regulates the cracking kinetics and accelerates intermediate transfer, thereby minimizing the production of side C_1–4 hydrocarbons resulting from over-cracking at the Ru sites and enhancing the yield of liquid fuels. This research contributes novel insights into catalyst design for the chemical upgrading of polyolefins into valuable chemicals, advancing the field of plastic waste recycling and sustainable chemical production. Full article

Ionic porous polymers have been widely utilized efficiently to anchor various metal atoms for the preparation of metal-embedded heteroatom-doped porous carbon composites as the active materials for electrocatalytic applications. However, the rational design of the heteroatom and metal elements in HPC-based composites remains a significant challenge, due to the tendency of the aggregation of metal nanoparticles during pyrolysis. In this study, a nitrogen (N)- and sulfur (S)-enriched ionic covalent organic framework (iCOF) incorporating viologen and thieno[3,4-b] thiophene (TbT) was constructed via Zincke-type polycondensation. The synthesized iCOF possesses a crystalline porous structure with a pore size of 3.05 nm, a low optical band gap of 1.88 eV, and superior ionic conductivity of 10^−2.672 S cm⁻¹ at 333 K, confirming the ionic and conjugated nature of our novel iCOF. By applying the iCOF as the precursor, a ruthenium and ruthenium(IV) oxide (Ru/RuO₂) nanoparticle-embedded N/S-co-doped porous carbon composite (NSPC-Ru) was prepared by using a two-step sequence of anion-exchange and pyrolysis processes. In the electrochemical nitrogen reduction reaction (eNRR) application, the NSPC-Ru achieves an impressive NH₃ yield rate of 32.0 μg h⁻¹ mg⁻¹ and a Faradaic efficiency of 13.2% at −0.34 V vs. RHE. Thus, this innovative approach proposes a new route for the design of iCOF-derived metal-embedded porous carbon composites for enhanced NRR performance. Full article

In the realm of green hydrogen energy, utilizing ruthenium (Ru) as a precious metal electrocatalyst for the hydrogen evolution reaction (HER) instead of platinum (Pt/C) is an excellent choice. Unfortunately, there are not enough active sites or electronic structures on a single Ru-based catalyst to significantly improve the oxygen evolution reaction (OER). Therefore, creating bifunctional water electrolysis catalysts that are stable and highly active in a variety of media continues to be a major challenge. The study describes a new method for creating an electrocatalyst (RuCuCl/NF-2) by using Ru to regulate an inert CuCl precursor. The enhanced mass transfer performance of the distinctive coral structure and the synergistic effect of RuCu emphasize its excellent water electrolysis activity, which is based on the self-assembly of Cu nanoparticles into a conical membrane structure. Overtaking the commercial benchmark Pt/C (~38 mV to reach 10 mA cm⁻²), the RuCuCl/NF-2 displays HER activity (~25 mV to reach 10 mA cm⁻²) in 1M KOH. This sheds light on how to create more sophisticated bifunctional electrocatalysts. Full article

Ruthenium-based catalysts were prepared through a deposition–precipitation approach, taking beta zeolites with Si/Al ratios of 12.5, 18.5, and 150, respectively, as supports, and 1–3 wt% loadings of metal. Their activation was performed in the presence of either H₂ or NaBH₄. The dispersion of the Ru species and the acid–base properties were influenced by both the preparation method and the activation protocol. The catalysts reduced under H₂ flow presented well-dispersed Ru(0) and RuO_x nanoparticles, while the reduction with NaBH₄ led to larger RuO_x crystallites and highly dispersed Ru(0). These characteristics exerted an important role in the hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL). The H₂ dissociation occurred via a heterolytic mechanism involving Lewis acid–base pairs associated with RuO_x and the framework oxygen (Si-O-Al) located near the zeolite pore edge. The Ru(0) nanoparticles activated the –C=O bond of the LA substrate, while the presence of the carrier zeolite Brønsted acid sites promoted the ring-closure esterification of the 4-hydroxyvaleric acid (4-HVA) intermediate to GVL. An optimal combination of these features was achieved for the catalyst with 3 wt% Ru and a Si/Al ratio of 150, which selectively converted LA (X_LA = 96.5%) to GVL (S_GVL = 97.8%) at 130 °C and 10 bars of H₂. Full article

The performance of the cathodic hydrogen evolution reaction (HER) in alkaline water electrolysis, an attractive hydrogen production technology, is highly dependent on efficient catalysts. Ruthenium (Ru), which is more affordable than platinum (Pt) and has a metal–hydrogen bond strength comparable to that of Pt, shows exceptional catalytic activity for the alkaline HER. Consequently, in recent years, research in the field of hydrogen production through alkaline water electrolysis has increasingly focused on Ru as a key element. This review first discusses the fundamentals of the alkaline HER, including principles, factors affecting its performance, and regulation strategies for its performance improvement. The research progress of ruthenium-based catalysts for the alkaline HER is then summarized with selected examples. The electronic structures of various ruthenium nanoparticles, ruthenium-M (M = noble metals and transition metals) heterogeneous catalysts, and ruthenium-based compounds are regulated by modulating the components and ligands of Ru atoms, aiming to achieve low water dissociation energies and optimal binding energies for hydrogen (H) and hydroxyl (−OH) groups, thereby enhancing the alkaline HER catalytic performance. Finally, the problems, challenges, and future development directions of the alkaline HER are proposed. Full article

Sodium hypophosphite is a promising green source for generating clean elemental hydrogen without pollutants. This study presents the development of an efficient heterogeneous catalyst, Ru/g-C₃N₄ (Ru/GCN), for hydrogen generation from sodium hypophosphite. The Ru/GCN catalyst demonstrates excellent activity under mild reaction conditions and maintains its effectiveness over multiple cycles without significant loss of activity. This easily separable and recyclable heterogeneous catalyst is straightforward to operate, non-toxic, eco-friendly, and provides a cost-effective alternative to the extensive use of expensive noble metals, which have limited industrial applications. The Ru/GCN catalyst was characterized using various material characterization and spectral methods, including powder X-ray diffraction (PXRD), Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), and X-ray photoelectron spectroscopy (XPS). Hypophosphite, combined with the catalytically active and recyclable Ru/GCN catalyst, forms a system with high potential for industrial-scale hydrogen production, suggesting promising avenues for further research and application. Full article

Materials based on polymer hydrogels have demonstrated potential as innovative Fenton catalysts for treating water. However, developing these polymer-supported catalysts with robust stability presents a significant challenge. This paper explores the development and application of polymer-supported heterogeneous Fenton catalysts for the environmental remediation of wastewater, emphasizing the enhancement of metal incorporation into catalysts for improved efficiency. The study begins with an introduction to the heterogeneous Fenton process and its relevance to wastewater treatment. It further delves into the specifics of polymer-supported heterogeneous Fenton catalysts, focusing on iron oxide, copper complexes/nanoparticles, and ruthenium as key components. The synthesis methods employed to prepare these catalysts are discussed, highlighting the innovative approaches to achieve substantial metal incorporation. Operational parameters such as catalyst dosage, pollutant concentration, and the effect of pH on the process efficiency are thoroughly examined. The catalytic performance is evaluated, providing insights into the effectiveness of these catalysts in degrading pollutants. Recent developments in the field are reviewed, showcasing advancements in catalyst design and application. The study also addresses the stability and reusability of polymer-supported heterogeneous Fenton catalysts, critical factors for their practical application in environmental remediation. Environmental applications are explored, demonstrating the potential of these catalysts in addressing various pollutants. The Conclusions offers future perspectives, underlining the ongoing challenges and opportunities in the field, and the importance of further research to enhance the efficacy and sustainability of polymer-supported heterogeneous Fenton catalysts for wastewater treatment. Full article

Metal-containing nanoparticles are now common in applications ranging from catalysts to biomarkers. However, little research has focused on per-particle metal content in multicomponent nanoparticles. In this work, we used single-particle inductively coupled plasma mass spectrometry (ICP-MS) to determine the per-particle metal content of silica nanoparticles doped with tris(2,2′-bipyridyl)ruthenium(II). Monodispersed silica nanoparticles with varied Ru doping levels were prepared using a water-in-oil microemulsion method. These nanoparticles were characterized using common bulk-sample methods such as absorbance spectroscopy and conventional ICP-MS, and also with single-particle ICP-MS. The results showed that averaged concentrations of metal dopant measured per-particle by single-particle ICP-MS were consistent with the bulk-sample methods over a wide range of dopant levels. However, the per-particle amount of metal varied greatly and did not adhere to the usual Gaussian distribution encountered with one-component nanoparticles, such as gold or silver. Instead, the amount of metal dopant per silica particle showed an unexpected geometric distribution regardless of the prepared doping levels. The results indicate that an unusual metal dispersal mechanism is taking place during the microemulsion synthesis, and they challenge a common assumption that doped silica nanoparticles have the same metal content as the average measured by bulk-sample methods. Full article

The development of direct dimethyl ether (DME) solid oxide fuel cells (SOFCs) has several drawbacks, due to the low catalytic activity and carbon deposition of conventional Ni–zirconia-based anodes. In the present study, the insertion of 2.0 wt.% Ru-Ce_0.7Zr_0.3O_2−δ (ruthenium–zirconium-doped ceria, Ru-CZO) as an anode catalyst layer (ACL) is proposed to be a promising solution. For this purpose, the CZO powder was prepared by the sol–gel synthesis method, and subsequently, nanoparticles of Ru (1.0–2.0 wt.%) were synthesized by the impregnation method and calcination. The catalyst powder was characterized by BET-specific surface area, X-ray diffraction (XRD), field emission scanning electron microscopy with an energy-dispersive spectroscopy detector (FESEM-EDS), and transmission electron microscopy (TEM) techniques. Afterward, the catalytic activity of Ru-CZO catalyst was studied using DME partial oxidation. Finally, button anode-supported SOFCs with Ru-CZO ACL were prepared, depositing Ru-CZO onto the anode support and using an annealing process. The effect of ACL on the electrochemical performance of cells was investigated under a DME and air mixture at 750 °C. The results showed a high dispersion of Ru in the CZO solid solution, which provided a complete DME conversion and high yields of H₂ and CO at 750 °C. As a result, 2.0 wt.% Ru-CZO ACL enhanced the cell performance by more than 20% at 750 °C. The post-test analysis of cells with ACL proved a remarkable resistance of Ru-CZO ACL to carbon deposition compared to the reference cell, evidencing the potential application of Ru-CZO as a catalyst as well as an ACL for direct DME SOFCs. Full article

Graphdiyne (GDY) is considered a very attractive support for metal nanocatalysts due to its unique structure and superior properties. The metal–GDY interaction can significantly affect the performance of catalysts. Herein, GDY nanotubes abundant in in situ formed Cu quantum dots (QDs) (Cu-GDYNT) are prepared using the electrospun polyacrylonitrile nanofibers collected on the surface of electrolytic Cu foil as templates. The diameter of the Cu-GDYNT is controllable and the uniform size of the embedded Cu QDs is about 2.2 nm. And then, the uniformly dispersed and highly active supported catalysts of ruthenium nanoparticles (Ru_x/Cu-GDYNT) are produced using the Cu-GDYNT as the support. Among them, the Ru₃/Cu-GDYNT exhibit outstanding HER performance at all pH levels. Only 17, 67 and 83 mV overpotential is required to reach a current density of 10 mA cm⁻² in 1.0 M KOH, 0.5 M H₂SO₄ and 1.0 M neutral PBS solutions, respectively. The sample exhibits 3000 CV cycle stability and 20 h continuous electrolysis without performance degradation in an alkaline medium. This work provides a new idea for constructing the GDY-supported metal nanocatalysts. Full article

The primary objective of this research was to develop efficient solid catalysts that can directly convert the lactic acid (LA) obtained from lignocellulosic biomass into alanine (AL) through a reductive amination process. To achieve this, various catalysts based on ruthenium were synthesized using different carriers such as multi-walled carbon nanotubes (MWCNTs), beta-zeolite, and magnetic nanoparticles (MNPs). Among these catalysts, Ru/MNP demonstrated a remarkable yield of 74.0% for alanine at a temperature of 200 °C. This yield was found to be superior not only to the Ru/CNT (55.7%) and Ru/BEA (6.6%) catalysts but also to most of the previously reported catalysts. The characterization of the catalysts and their catalytic results revealed that metallic ruthenium nanoparticles, which were highly dispersed on the external surface of the magnetic carrier, significantly enhanced the catalyst’s ability for dehydrogenation. Additionally, the -NH₂ basic sites on the catalyst further facilitated the formation of alanine by promoting the adsorption of acidic reactants. Furthermore, the catalyst could be easily separated using an external magnetic field and exhibited the potential for multiple reuses without any significant loss in its catalytic performance. These practical advantages further enhance its appeal for applications in the reductive amination of lactic acid to alanine. Full article

This study aimed to probe the effect of heat treatment on zinc oxide nanoparticles doped with ruthenium through a chemical co-preparation technique. Pure ZnO and Ru-doped ZnO nanoparticles, with the general formula Zn_1−x−Ru_xO, were synthesized for 0 ≤ x ≤ 0.04. Using the same starting precursors, the growth temperature was 60 °C and 80 °C for set A and set B, respectively, whereas the calcination temperature was 450 °C and 550 °C for set A and set B, respectively. For the structure investigation, X-ray powder diffraction (XRD) revealed that the crystallite size of set A was smaller than that of set B. For x = 0.04 in set B, the maximum value of the crystallite size was attributed to the integration of Ru³⁺ ions into interstitial sites in the host causing this expansion. Fourier transform infrared spectroscopy (FTIR) confirmed the formation of zinc oxide nanoparticles by showing a Zn-O bonding peak at 421 cm⁻¹. For x = 0.04 in set B, the divergence confirmed the change in bonding properties of Zn²⁺ distributed by Ru³⁺ doping, which verifies the presence of secondary-phase RuO₂. Using UV–visible spectroscopy, the energy gap of set A swings as ruthenium doping increases. However, in set B, as the crystallite size decreases, the energy gap increases until reversing at the highest concentration of x = 0.04. The transition from oxygen vacancy to interstitial oxygen, which is associated with the blue peak (469 nm), increases in set A under low heating conditions and decreases in set B as Ru doping increases, as revealed in the photoluminescence optical spectra of the samples. Therefore, ruthenium doping proves a useful surface defect and generates distortion centers in the lattice, leading to more adsorption and a remarkable advantage in sunscreen and paint products used for UV protection. Full article

Recently discovered cis-dichloro benzylidene phosphite complexes are latent catalysts at room temperature and exhibit exceptional thermal and photochemical activation behavior in olefin metathesis reactions. Most importantly, the study of these catalysts has allowed their introduction in efficient 3-D printing applications of ring-opening metathesis derived polymers and the control of chromatically orthogonal chemical processes. Moreover, their combination with plasmonic Au-nanoparticles has given rise to novel smart materials that are responsive to light. Given the importance of the ligand shell in the initiation and reactivity behavior of this family of complexes, we set out to investigate the effect of anionic ligand exchange. Thus, we report herein two new ruthenium benzylidene benzylphosphite complexes where the chloride anionic ligands have been replaced by bromide and iodide anions (cis-Ru-Phos-Br₂ & cis-Ru-Phos-I₂). The thermal and photochemical activations of these dormant catalysts in a variety of ring-closing and ring-opening metathesis polymerization (RCM and ROMP) reactions were thoroughly studied and compared with the previously known chloride precatalyst. Photochemical RCM studies provided similar results, especially in non-hindered reactions, with the UV-A wavelength being the best in all cases. On the other hand, the thermal activation profile exposed that the anionic ligand significantly affects reactivity. Notably, cis-Ru-Phos-I₂ disclosed particularly impressive initiation efficiency compared to the other members of the family. Full article