Metal Nanoparticles Research Articles

Synthesis of multifunctional silver oxide, zinc oxide, copper oxide and gold nanoparticles for enhanced antibacterial activity against ESKAPE pathogens and antioxidant, anticancer activities using Momordica cymbalaria seed extract

Rising emergence in public health due to antibiotic-resistant of ESKAPE pathogens, diseases related to oxidative damage and cancer has driven the urgent need to develop potent therapeutics for resistant bacterial strains, free radical scavenging and cancer. The present study involves Momordica cymbalaria seed extracts mediated synthesis of metal nanoparticles and to evaluate its ameliorative potency against ESKAPE pathogens, free radicals and cancer cells. The study includes therapeutic approaches to target pathogenic biofilms relating phyto-therapeutics with nanotechnology. In the present investigation, we have synthesized four metal oxide nanoparticles of Silver, Zinc, Copper (Ag2O, ZnO and CuO), and Gold nanoparticles (Au NPs) using the seed extracts of M. cymbalaria. The synthesized nanoparticles were characterized by various biophysical techniques like X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) Field-Emission Scanning Electron Microscopy (FESEM) with energy-dispersive X-ray spectroscopy (EDX) and High-Resolution Transmission Electron Microscopy (HR-TEM) with Selected Area Electron Diffraction (SAED). Agar well diffusion methods, or Antimicrobial methods (MIC, MBC, and MBIC), DPPH/ABTS free radical scavenging assay, MTT/apoptotic studies and protein/DNA damage inhibition assays were performed to evaluate the antibacterial, anticancer and antioxidant activities. Crystalline properties of metal oxides NPs were established by XRD pattern and the presence of alcohol or phenol, ketone, and amine groups in M. cymbalaria seed was confirmed by FTIR analysis. That participates in the reduction of Ag+, Cu+, Zn+, and Au+ ions to NPs. All the nanoparticles showed dose-dependent antibacterial, anticancer and antioxidant activity. Protein and DNA oxidation inhibition assays demonstrated an efficient quenching effect of proxy radicals by all the NPs. Therefore, M. cymbalaria -mediated synthesis of metal NPs can be used as an alternative to toxic physical or chemically mediated synthesis that can be applied to develop multifunctional nanoparticles as efficient therapeutics.

Use of Residual Malt from an Artisanal Beer Brewing Process in the Biosynthesis of Silver Nanoparticles Mediated by Nucleating and Structure-Directing Agents.

Biosynthesized silver nanoparticles (AgNPs) are widely used in varied applications, which are morphology dependent. Consequently, a morphology-controlled synthesis is mandatory. Although there are several studies focused on the plant extract-based biosynthesis of metallic nanoparticles, the use of extracts obtained from agro-wastes is scant. Furthermore, information regarding morphology modification through the use of additional agents is even more scarce. Thus, in this study, AgNPs were synthesized using a malt extract (ME) obtained from an artisanal beer brewing process residue. Additionally, sodium chloride (NaCl), gum arabic (GA), and talc (T) were used in an attempt to modify the morphology of AgNPs. XRD, DLS, SEM, and TEM results demonstrate that stable AgNPs of different sizes and shapes were synthesized. FTIR, HPLC analysis, and the quantification of total proteins, free amino acids, reducing sugars, and total polyphenols before and after AgNPs synthesis showed that ME biomolecules allowed them to act as a source of reducing and stabilizing agents. Therefore, this study provides evidence that ME can be successfully used to biosynthesize AgNPs. Additionally, the antibacterial activity of AgNPs against Gram-negative and Gram-positive bacteria was evaluated. Results indicate that AgNPs show a higher antibacterial activity against Gram-positive bacteria.

An evaluation of antimicrobial potency of silver nanoparticles synthesised from Fusarium sp.

Biological synthesis of metal nanoparticles has caught the interest of scientists due to the environment friendly synthesis approach which yields metallic nanoparticles with antimicrobial potency. In the present study silver nanoparticles were produced using a green method with the assistance of Fusarium sp. fungal cell filtrate and their antimicrobial potency was explored. The silver nanoparticles depicted a surface plasma resonance of 434 nm when run in the Ultra Violet–Visible Spectrophotometer. The functional group present in the nanoparticles were investigated using an Attenuated Total Reflectance-Fourier Transform Infrared where –OH, C–H, amide I and amide II functional groups were notable. The morphology and crystallinity of the produced silver nanoparticles was investigated with the help of a Scanning Electron Microscope and X-ray Diffraction. The X-ray diffraction results revealed that the nanoparticles were crystalline in nature with a face centred cubic structure and a crystallite size of 38.5 nm. The Scanning Electron Microscope revealed that the nanoparticles were spherical with sizes ranging between 3 to 43 nm. Antimicrobial studies of the synthesised silver nanoparticles were conducted at different concentrations (1 mM, 10 mM, 20 mM and 100 mM) against disease causing microorganisms Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa, the results showed that at a concentration of 1 mM there was no inhibition but as the concentration was increased to 20 mM and 100 mM, there was a notable inhibition with the maximum inhibition zone being 17 ± 0.6 mm.

Core–shell CoN@Co ultra-stable nanoparticles on biochar for contamination remediation in water and soil

Nanomaterials have been extensively employed in various applications over the past several decades, however, the stability of functional nanoparticle catalysts (NPCs) for effective degradation of organic contaminants remains a significant challenge. Herein, we present a cost-effective biochar loaded uniformly dispersed ultra-stable Co nanoparticles with an average diameter of 8 nm as a highly efficient peroxymonosulfate (PMS) activation catalyst. The reactive radicals produced from the catalyst/PMS system are able to degrade several model organic pollutants of environmental and public health concerns, including trichlorobiphenyl, bisphenol A and diethyl phthalate, with less pH limitation and Co2+ leaching. Mechanism investigation demonstrates that the CoN plays the key role in the catalyst stability and PMS activation via acid resistance and electron bridging effects, respectively. Meanwhile, the incorporation of nitrogen (N) and sulfur (S) atoms within the substrate is considered to bolster the adhesion strength between metal nanoparticles and the carbon matrix via strong metal-support interaction. The catalyst was further applied in practical treatment of water and soil polluted by organic pollutants, exhibiting a satisfactory degradation efficiency (> 90% in 60 min) for environmental applications.

A double‐edged sword: The complex interplay between engineered nanoparticles and platelets

AbstractNanoparticles (NP) play a crucial role in nanomedicine, serving as carriers for localized therapeutics to allow for precise drug delivery to specific disease sites and conditions. When injected systemically, NP can directly interact with various blood cell types, most critically with circulating platelets. Hence, the potential activation/inhibition of platelets following NP exposure must be evaluated a priori due to possible debilitating outcomes. In recent years, various studies have helped resolve the physicochemical parameters that influence platelet‐NP interactions, and either emphasize nanoparticles' therapeutic role such as to augment hemostasis or to inhibit thrombus formation, or conversely map their potential undesired side effects upon injection. In the present review, we discuss some of the main effects of several key NP types including polymeric, ceramic, silica, dendrimers and metallic NPs on platelets, with a focus on the physicochemical parameters that can dictate these effects and modulate the therapeutic potential of the NP. Despite the scientific and clinical significance of understanding Platelet‐NP interactions, there is a significant knowledge gap in the field and a critical need for further investigation. Moreover, improved guidelines and research methodologies need to be developed and implemented. Our outlook includes the use of biomimetic in vitro models to investigate these complex interactions under both healthy physiological and disease conditions.

Green Synthesis of Gold Nanoparticles Using Liquiritin and Other Phenolics from Glycyrrhiza glabra and Their Anti-Inflammatory Activity.

Phenolic compounds are the main phytochemical constituents of many higher plants. They play an important role in synthesizing metal nanoparticles using green technology due to their ability to reduce metal salts and stabilize them through physical interaction/conjugation to the metal surface. Six pure phenolic compounds were isolated from licorice (Glycyrrhiza glabra) and employed in synthesizing gold nanoparticles (AuNPs). The isolated compounds were identified as liquiritin (1), isoliquiritin (2), neoisoliquiritin (3), isoliquiritin apioside (4), liquiritin apioside (5), and glabridin (6). The synthesized AuNPs were characterized using UV, zeta sizer, HRTEM, and IR and tested for their stability in different biological media. The phenolic isolates and their corresponding synthesized NP conjugates were tested for their potential in vitro cytotoxicity. The anti-inflammatory effects were investigated in both normal and inflammation-induced settings, where inflammatory biomarkers were stimulated using lipopolysaccharides (LPSs) in the RAW 264.7 macrophage cell line. LPS, functioning as a mitogen, promotes cell growth by reducing apoptosis, potentially contributing to observed outcomes. Results indicated that all six pure phenolic isolates inhibited cell proliferation. The AuNP conjugates of all the phenolic isolates, except liquiritin apioside (5), inhibited cell viability. LPS initiates inflammatory markers by binding to cell receptors and setting off a cascade of events leading to inflammation. All the pure phenolic isolates, except isoliquiritin, neoisoliquiritin, and isoliquiritin apioside inhibited the inflammatory activity of RAW cells in vitro.

Enhanced Light-Matter Interaction in Metallic Nanoparticles: A Generic Strategy of Smart Void Filling.

The intrinsic properties of materials play a substantial role in light-matter interactions, impacting both bulk metals and nanostructures. While plasmonic nanostructures exhibit strong interactions with photons via plasmon resonances, achieving efficient light absorption/scattering in other transition metals remains a challenge, impeding various applications related to optoelectronics, chemistry, and energy harvesting. Here, we propose a universal strategy to enhance light-matter interaction, through introducing voids onto the surface of metallic nanoparticles. This strategy spans nine metals including those traditionally considered optically inactive. The absorption cross section of void-filled nanoparticles surpasses the value of plasmonic (Ag/Au) counterparts with tunable resonance peaks across a broad spectral range. Notably, this enhancement is achieved under arbitrary polarizations and varied particle sizes and in the presence of geometric disorder, highlighting the universal adaptability. Our strategy holds promise for inspiring emerging devices in photocatalysis, bioimaging, optical sensing, and beyond, particularly when metals other than gold or silver are preferred.

In vitro assessment of the anthelmintic activity of copper oxide and zinc oxide nanoparticles on egg and adult stages of Fasciola hepatica: evidence on oxidative stress biomarkers, and DNA damage

ObjectivesFasciolosis is of significant economic and public health importance worldwide. The lack of a successful vaccine and emerging resistance in flukes to the drug of choice, triclabendazole, has initiated the search for alternative approaches. In recent years, metallic nanoparticles have been extensively investigated for their anthelmintic effects. This study investigates the in vitro anthelmintic activity of copper oxide and zinc oxide nanoparticles against Fasciola hepatica.MethodsThe in vitro study was based on egg hatchability test (EHA), adult motility inhibition tests, DNA damage, ROS levels, as well as several biomarkers of oxidative stress, including glutathione peroxidase (GSH) and glutathione S-transferase (GST), superoxide dismutase (SOD) and malondialdehyde (MDA). For this purpose, different concentrations of copper oxide nanoparticles (CuO-NPs) and Zinc oxide nanoparticles (ZnO-NPs) (1, 4, 8, 12, and 16 ppm) were used to evaluate the anthelmintic effect on different life stages, including egg and adults of Fasciola hepatica, over 24 h.ResultsIn vitro treatment of F. hepatica worms with both CuO-NPs and ZnO-NPs could significantly increase ROS production and oxidative stress induction (decreased SOD, GST and GSH and increased MDA) compared to control group.ConclusionsBased on the results, it seems that CuO-NPs and ZnO-NPs may be effective in the control and treatment of F. hepatica infection. Further research is needed to investigate their potential for in vivo use in the treatment of parasitic infections.

Synthesis of Novel Nanocomposite CaO/AC/ZnO from Biogenic Wastes of Date Palm Seeds from The Najran Region (Saudi Arabia) and Eggshells for Degradation of Methylene Blue

Metal nanoparticles and activated carbon-based nanocomposite materials are gaining popularity due to their numerous potential applications in a wide range of materials science areas. The current study aims to create novel photocatalyst frameworks for nanocomposites that were synthesized from biogenic waste and used to photodegrade methylene blue (MB) in wastewater under visible light. The activated carbon from date seeds was calcinated at a temperature of 700°C for two hours, and its surface was improved using zinc oxide nanoparticles and calcium oxide nanoparticles manufactured from eggshells at 900oC. XRD, FT-IR, SEM, BET, and TEM analyses were used to characterize the produced nanocomposites. The synthesized nanocomposite photocatalytic activity was evaluated by degrading MB dyes, its model of water pollution. The results showed that the nanocomposite CaO/AC/ZnO has a mesoporous structure with great sorption capability. Also, the photodegradation efficiency of MB using AC, CaO, AC/ZnO, and CaO/AC/ZnO nanocomposite was 33.23, 37.58, 54.61, and 88.92%, respectively, after100 min of sunlight irradiation indicating that photodegradation efficiency increases by improving the surface properties of AC. The CaO/AC/ZnO nanocomposite exhibited a 96.7% removal efficiency of MB following 120 min of visible light radiation exposure. Therefore, the CaO/AC/ZnO nanocomposite has a promising opportunity to function as a versatile and effective photocatalyst for photodegradation of organic dyes in wastewater.

The Impact of Inorganic Systems and Photoactive Metal Compounds on Cytochrome P450 Enzymes and Metabolism: From Induction to Inhibition.

While cytochrome P450 (CYP; P450) enzymes are commonly associated with the metabolism of organic xenobiotics and drugs or the biosynthesis of organic signaling molecules, they are also impacted by a variety of inorganic species. Metallic nanoparticles, clusters, ions, and complexes can alter CYP expression, modify enzyme interactions with reductase partners, and serve as direct inhibitors. This commonly overlooked topic is reviewed here, with an emphasis on understanding the structural and physiochemical basis for these interactions. Intriguingly, while both organometallic and coordination compounds can act as potent CYP inhibitors, there is little evidence for the metabolism of inorganic compounds by CYPs, suggesting a potential alternative approach to evading issues associated with rapid modification and elimination of medically useful compounds.

Analytical study of linear optical properties of metal nanoparticle trimers: the impact of dipole-dipole interaction on different modes of configuration

In this study, we theoretically investigate the linear properties of a metal nanoparticle (MNP) trimer. Three identical spherical nanoparticles (NPs) whose centers are equidistantly oriented on a same straight line are considered. Using the solid core approximation for NPs and considering interaction between particles through induced electric dipoles, the motion equation of each NP conduction electrons is analytically solved. Some appropriately approximated expressions are derived for the permittivity of each NP based on a Drude-like model, allowing the clear observation of the contribution of inter-particle interaction. Depending on the orientation of the trimer axis and incident laser beam geometry (i.e., orientation of electromagnetic (EM) fields and wave vector of laser beam), three different configurations or modes are considered. The extinction efficiency of each NP as a function of wavelength is plotted, revealing that when the laser electric field is perpendicular to the symmetry axis of the trimer, it increases compared to the case of non-interactional single NP, and its plasmon resonance peak experiences a red shift. For other cases where the electric field of the laser beam is parallel to the trimer axis, the extinction efficiency of each NP decreases, and its peak shifts to the blue. In all cases, the effect of interaction on the optical properties of the middle NP is greater than on the other NPs.

Surface-enhanced Raman spectroscopy (SERS) substrate based on gold nanostars–silver nanostars for imidacloprid detection

Surface-enhanced Raman spectroscopy (SERS) is a powerful molecular spectroscopy technique that combines Raman spectroscopy with nanostructured metallic surfaces to amplify the Raman signals of target molecules by more than 103. The high sensitivity of SERS poses a significant opportunity for pesticide detection in complex matrices at ultralow concentrations. In this study, we improved the SERS sensitivity for imidacloprid (IMD) by employing silver nanostars (AgNs) coated with gold nanostars (AuNs) as the SERS-active substrate. The SERS response towards IMD detection increased based on the combination of AuNs and AgNs on the substrate surface. The intensity of the SERS signal of IMD using the AuNs/AgNs substrate increased compared to using individual metal nanoparticle substrates. The excellent reproducibility of SERS intensity using the AuNs/AgNs substrate was achieved with a low relative standard derivative (RSD) of 4.87% for 20 different spots on the same sample and 5.19% for 20 different samples. This detection system can be used for multiple tests, which is crucial for the advancement of handheld sensors designed for field use, where minimal or no high-level technical support is accessible.

Synthesis, Characterization and Application of Biogenic Silver Nanoparticles as Antibacterial and Antifungal Agents

In order to provide a straightforward, affordable, and environmentally friendly process for the synthesis of metallic nanoparticles, scientists are turning to natural ways like employing plant extract in response to rising antimicrobial resistance and the desire for novel biocidal agents. In this study, we evaluated the efficacy of phyto-fabricated silver nanoparticles and antimicrobial agents against selected indoor bacterial and fungal strains isolated from the lecture and office rooms of Chukwuemeka Odimegwu Ojukwu University, Uli Nigeria. The indoor microorganisms were isolated, identified, and quantified using standard methods. To prepare and generate the aqueous extract employed in the biological synthesis of the silver nanoparticle, fresh soursop seeds were room dried, crushed, heated to boiling, and double filtered. The phyto-fabricated nanoparticles were centrifuged, dried and used for physicochemical characterization and antimicrobial assay. The synthesized silver nanoparticles were characterized using UV-Vis spectrophotometry, Fourier transformed Infra-Red Spectroscopy and scanning electron microscopy analyses. The antimicrobial assay was carried out using agar well diffusion method. The results revealed that Aeromonas, Pseudomonas, Staphylococcus, Vibrio, Rhizopus, Aspergillus, Penicillium and Microsporum were identified as the predominant potential indoor bacterial and fungal pathogenic strains. The characterized biogenic nanoparticles revealed the optical, spectral and morphological features unique to silver nanoparticles. Also, the antibacterial screening revealed that the highest zone of inhibition was observed against Vibrio sp. (27.50 ± 7.5 mm) at a concentration of 30 μg/mL while standard antifungal drug (ketoconazole) had the highest zone of inhibition of 21.0 ± 1.0 mm at 3.25 μg/mL against Microsporum gypseum while standard antifungal drug (ketoconazole) and Ag-NPs had the lowest zone of inhibition of 11.0 ± 1.0 mm at 15.0 μg/mL and 7.5 μg/mL against Rhizopus sp. and Aspergillus flavus, respectively. The negative control (DMSO) had no zone of inhibition on any of the potential indoor bacterial and fungal pathogenic strains. Statistically, there was significant (P < 0.05) inhibition of bacterial and fungal pathogenic strains among the means of treatment doses of A. muricata AgNPs, ciprofloxacin and ketoconazole standard antibiotics. The excellent antimicrobial inhibition of the tested indoor bacterial and fungal strains by the A. muricata fabricated silver nanoparticles even at MIC of 3.25 μg/mL could be exploited as biostatic and biocidal agents where there is contamination or public health risk of pathogenic indoor bacteria and fungi.

Synthesis of biopolymer blends nanocomposites embedded with mono-(Ag, Fe) and bi-(Ag-Fe) metallic nanoparticles using an eco-friendly approach for antimicrobial activities.

Plant-mediated solution casting is used to develop eco-friendly polymer blend nanocomposites from polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP) doped with Silver (Ag), Ferrous (Fe) monometallic and Silver-Ferrous (Ag-Fe) bimetallic nanoparticles (NPs). These nanocomposites were studied to understand their electromagnetic interface (EMI) shielding efficiency and antimicrobial activities, besides evaluating their physical and chemical properties. The Fourier transform infrared (FTIR), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and energy dispersive X-ray (EDX) characterization techniques were used to examine the interactions between the polymers, the presence of silver and ferrous particles in the composites, the crystallinity shift, the surface morphology, the shape and size of the nanoparticles and the distribution of the nanoparticles in the composites. The FTIR spectra showed the interactions among the components of the composites. According to XRD spectra, the incorporation of nanoparticles into the PVA polymer significantly reduced the crystalline character of the polymer from 0.38 to 0.24 for the composition consisting of silver and iron nanoparticles in equal proportion. The results from SEM, EDX and XRD corroborate the presence of nanoparticle forms. The thermogravimetric analysis (TGA) tests reveal that the thermal stability of bimetallic composites is greater than that of monometallic composites. The tensile properties showed that the addition of nanoparticles to the PVA/PVP polymer matrix increased its mechanical strength from 59.3MPa to 85.5MPa. We examined its efficacy against Escherichia coli, Staphylococcus aureus and Candida albicans as microorganisms. Good antibacterial and antifungal activity was observed. The bimetallic composites demonstrated greater activity than monometallic composites against these bacterial and fungal species. All bimetallic nanocomposites have shown enhanced, loss due to reflection, loss due to absorption, and the total EMI shielding efficiency at 8GHz (X-band) and 16GHz (Ku-band) frequency. All these results ratify, that these newly developed bio nanocomposites are most suitable in many applications, in EMI shielding, nanotechnology, and medical fields.

Organic pollutants photodegradation increment with use of TiO2 nanotubes decorated with transition metals after pulsed laser treatment

Among various titanium(IV) oxide (TiO2, titania) structures, 1D nanotubes (TiO2 NTs) produced during the two-electrode anodization process, are extensively utilized in sensors or supercapacitors as well as in photo(electro)catalytic water splitting. However, due to wide bandgap and fast electron-hole recombination additional modifications, mostly concerned on materials surface, are required. According to the recent research, TiO2 NTs photo(electro)catalytic characteristic were markedly improved by the combination of surface decoration with transition metal nanoparticles further treated with the laser beam. Nevertheless, until recently, the photocatalytic ability of laser-treated TiO2 NTs for recalcitrant chemicals degradation were hardly described. In this regard, our work focuses on obtaining long, about 7.3 μm TiO2 NTs (L-TiO2 NTs), together with their photoactivity and physicochemical characteristics, as well as their alterations following surface modification utilizing transition metals (tungsten, chromium and nickel) together with laser treatment. Obtained L-TiO2 NTs are characterized by over 13.5 times larger BET surface area in comparison to reference spaced TiO2 NTs with approximately 2 μm length (0.61 m2 g−1 and 0.05 m2 g−1, respectively). This allowed for increasing of the materials photocatalytic activity in both UV–vis and vis light. Additionally, phenol photodegradation reached up to 34% (0.21·10−2 min−1) for tungsten-modified titania after laser annealing at 20 mJ cm2 fluence. The reaction mechanism research revealed that reduction of organic pollutants concentration was primarily caused by superoxide radical anions •O2−. Furthermore, obtained modified L-TiO2 NTs showed remarkable durability without losing their initial activity over ten photocatalytic cycles.

Green Synthesis of Metal Nanoparticles

In the last two decades, metal nanoparticles have been created much interest among the scientists due to its application in different field such as sustainable energy, food safety, environmental science, catalysis, medicine etc. The synthesis of the metal nanoparticles in the chemical method involves large energy consumption, environmental pollution which leads to health problems. The green synthesis of metal nanoparticles using plant extract as the reducing agent are more beneficial than the chemical methods due to low cost, environment friendly, health safety. In this review, green synthesis of Ag NP, Au NP, Pd, Pt NP and their applications are discussed.

Unveiling the effect of Pt addition on Ag/C catalyst for enhanced glycerol electrooxidation

This study investigates the performance of Ag/C and a range of Ag100-xPtx/C nanoparticles as electrocatalysts for glycerol electrooxidation reaction (GEOR). Low amounts of Pt (<2 %) were spontaneously deposited on Ag-supported nanoparticles using Ag as a sacrificial metal. The primary aim of the study is to determine the impact of adding a small amount of Pt to the Ag/C catalyst. Cyclic voltammetry is employed to assess the electrocatalyst's performance, while in situ Fourier Transform Infrared (FTIR) spectroscopy is used to examine the formed reaction intermediates and products. Additionally, physical characterization techniques such as XRD and XPS are applied to analyze the material structure. The Ag100-xPtx/C series of catalysts show a significant improvement in the glycerol oxidation process with the addition of 0.25 % of Pt to the material composition compared to pure Ag. It is observed that the enhancement performance reaches a limit at a Pt composition of approximately 7 % in the metallic nanoparticles, indicating that further increases in Pt content do not yield additional improvements. The in situ FTIR studies reveal that the presence of Pt on the Ag surface leads to a distinct glycerol electrooxidation mechanism compared to using Ag alone. Small amounts of Pt deposits promote C−C−C bond breaking, as evidenced by the selective formation of formic acid and CO2. FTIR results demonstrate a preference for carboxylic acid formation, with no significant evidence of dihydroxyacetone (DHA) production. The findings emphasize the critical role of Pt composition in the electrooxidation of glycerol paving the way for the design and development of more efficient and sustainable electrooxidation catalysts.

Enhancing the tribological performance of hydroxypropyl methylcellulose composite coatings through nano-sized metal and oxide additives: A comparative study

Cellulose, due to its excellent mechanical and tribological properties and eco-friendliness, is suitable for environmentally friendly applications. However, its application is limited due to susceptibility to wear and damage under stress during usage. This study introduces nanosized aluminum, copper, alumina, and copper oxide into composite materials to tackle the challenges of wear and damage. This approach aims to improve the tribological performance of Hydroxypropyl methylcellulose (HPMC) composite coatings significantly. The additive particles enhanced the load-bearing capacity and wear properties of cellulose-based composite coatings. The velocity accommodation mode was provided by nano-metals through S3M2 (interaction of metal particle additives through a third-body mechanism), while for nano-oxides, it was S3M4 (expulsion of nanoparticles from the wear mark to the outer contact zone). Due to the higher specific stiffness and strength of oxides, nanofillers in the composite offered better load resistance than nano-metals, resulting in a smaller actual contact area during wear. Therefore, metal oxide nanofillers enhanced tribological properties more effectively than metal nanoparticles. Finally, detailed explanations of the tribological evidence and discussions on the mechanism were conducted.

Photo‐promoted rapid reconstruction induced alterations in active site of Ag@amorphous NiFe hydroxides for enhanced oxygen evolution reaction

AbstractThe dynamic surface self‐reconstruction behavior in local structure correlates with oxygen evolution reaction (OER) performance, which has become an effective strategy for constructing the catalytic active phase. However, it remains a challenge to understand the mechanisms of reconstruction and to accomplish it fast and deeply. Here, we reported a photo‐promoted rapid reconstruction (PRR) process on Ag nanoparticle‐loaded amorphous Ni‐Fe hydroxide nanosheets on carbon cloth for enhanced OER. The photogenerated holes generated by Ag in conjunction with the anodic potential contributed to a thorough reconstruction of the amorphous substrate. The valence state of unsaturated coordinated Fe atoms, which serve as active sites, is significantly increased, while the corresponding crystalline substrate shows little change. The different structural evolutions of amorphous and crystalline substrates during reconstruction lead to diverse pathways of OER. This PRR utilizing loaded noble metal nanoparticles can accelerate the generation of active species in the substrate and increase the electrical conductivity, which provides a new inspiration to develop efficient catalysts via reconstruction strategies.

A universal and ultrafast method for fabricating a library of nanocellulose-supported metal nanoparticles

Using nanocatalysts to catalyze water electrolysis for hydrogen production is an ideal solution to address the energy crisis. The most well-adopted fabrication methods for nanocatalysts are tube furnace annealing, Hydrothermal method, etc., hardly satisfying the trade-off among coarsening, dispersity, and particle size due to mutual restrictions. Herein, a universal, ultrafast and facile cellulose nanometer whiskers-high temperature shock (CNW-HTS) method was reported for fabricating a library of ultrafine metal nanoparticles with uniform dispersion and narrow size distribution. The metal-anchor functional groups in CNW (i.e., –OH and –COOH) and the characteristics of the HTS method for ultrafast heating and powerful quenching synergistically contribute to the successful synthesis of metal nanoparticles. As an initial demonstration, the as-prepared Pt nanocatalyst (η10 ​mA ​cm−2 ​= ​51.8 ​mV) shows more excellent catalytic hydrogen evolution reaction (HER) performance than the Pt catalyst prepared in the tubular furnace (η10 ​mA ​cm−2 ​= ​169.4 ​mV). This rapid and universal CNW-HTS method can pave the way for nanomanufacturing to produce high-quality metal nanoparticles, thereby expanding applications of energy conversion and electrocatalysis.