Metal Nanoparticle Composites Research Articles

Sonochemical deposition of gold nano-shells on suspended polymeric spheres

Metal nanoparticles have drawn great interest due to their unique properties for applications in the fields of catalysis, biomedicine and environmental science depending on the architecture of the metal nanoparticle composites. Amongst different designing routes, the chemical template deposition offers great flexibility in terms of the template selection and interfacial interactions, giving rise to controllable designs. In order to control over nanoparticle size distribution and deposition efficiency, a sonochemical approach has been systematically followed in this study. Key parameters of the ultrasound-assisted deposition procedures during the seeding step to synthesise gold nanoparticle-coated poly(styrene) beads were investigated. The impact of the solution pH and the ultrasonic frequency on the template deposition was examined at 139, 300, 500 and 1000 kHz. The results, monitored by transmission electron spectroscopic imaging, show that the highest gold deposition was achieved at 300 kHz, revealing the mechanistic details of the nucleation-crystal growth behaviour as a function of ultrasonic frequency and reaction time. In addition, the concentration ratio between gold ions and poly(styrene) beads was varied. The highest deposition coverage and smallest particle size were reached at 0.05 mM and 2.5 mg, respectively. The proposed mechanism of the MNPs formation and deposition behaviour were then discussed based on the tested parameters.

Nanoparticles for Active and Sustainable Fuel Cell Cathodes

Depletion of fossil fuels and environmental pollution raised interest in new technologies for sustainable energy production, conversion, and storage, among which fuel cell technology is greatly studied, in both academia and industry. Proton exchange membrane fuel cells (PEMFCs) are reputed energy devices, due to their high conversion efficiency and low environmental pollution.1 Nowadays, Pt-based catalysts exhibit the best electrocatalytic activity towards oxygen reduction reaction (ORR), but enhancing their catalytic efficiency and reducing costs are essential for commercializing fuel cell technology.2 Our interest relies with the development of Pt-based nanoalloys2,4 via solution organometallic chemistry approach.3 This approach allows control over the composition, structure, and morphology of metal nanoparticles, and could lead to increased catalytic activity and long-term stability by revealing more active sites of the catalyst. Additionally, the ability to alloy with a range of metals for producing bimetallic compounds is one of the key advantages of this approach.In this communication, the synthesis of Pt-based nanoparticles and their characterization by state-of-the-art techniques such as ICP, EA, IR, TEM and HR-TEM will be described. The influence of the Pt complexes used as precursors and of the reaction conditions on the morphology of the Pt nanoparticles will be shown. The obtained nanostructures offer interesting starting materials to incorporate other metals, such as transition or rare earth metals, in order to have nanoalloys and study their performance in ORR in comparison to pure Pt catalysts.

Impact of pH on the Catalytic Activity of Metal Nanoparticles in Organic Reactions in Ghana

Purpose: The aim of the study was to assess the impact of pH on the catalytic activity of metal nanoparticles in organic reactions in Ghana. Methodology: This study adopted a desk methodology. A desk study research design is commonly known as secondary data collection. This is basically collecting data from existing resources preferably because of its low cost advantage as compared to a field research. Our current study looked into already published studies and reports as the data was easily accessed through online journals and libraries. Findings: The pH of the reaction medium can significantly influence the surface charge, morphology, and composition of metal nanoparticles, consequently affecting their catalytic performance. At specific pH levels, the protonation or deprotonation of functional groups on the nanoparticle surface can occur, altering the electronic properties and reactivity of the catalyst. Additionally, pH can influence the stability of metal nanoparticles and their interaction with reactants, intermediates, and products. Studies have shown that optimizing pH conditions can enhance catalytic activity, selectivity, and recyclability of metal nanoparticles in various organic transformations, including hydrogenation, oxidation, and coupling reactions. Understanding the pH dependence of metal nanoparticle catalysis is crucial for the rational design and optimization of efficient catalytic systems for organic synthesis. Implications to Theory, Practice and Policy: Surface chemistry theory, electrochemical theory and colloid chemistry theory may be used to anchor future studies on assessing the impact of pH on the catalytic activity of metal nanoparticles in organic reactions in Ghana. Implementation of advanced experimental techniques for real-time monitoring of pH effects on nanoparticle catalysis. Techniques such as in situ spectroscopy and surface characterization methods can provide valuable insights into dynamic changes in nanoparticle structure and reactivity during catalytic reactions. Integration of pH considerations into regulatory frameworks and guidelines for sustainable catalysis.

Microwave-induced biomass pyrolysis coupled with hydrothermal char composites catalysis to selectively prepare phenols-rich liquid products

In this study, three types of hydrothermal char-supported metal nanoparticle composites (HCM-Fe, HCM-Co, and HCM-Ni) were prepared using pinewood as the raw material via an ion hydrothermal pretreatment followed by microwave heating method, which were then served as both catalysts and microwave absorbers to enhance the rapid pyrolysis of pine wood particles for the selective preparation of phenols-rich bio-oil. The combined effects of hydrothermal carbonization and microwave heating enriched the pore structure of the composite surface, yielding ordered carbon structures such as carbon microspheres, carbon nanotubes, and graphite layers. Also, metal nanoparticles were generated and uniformly anchored on the hydrothermal char matrix by the graphite layers. The three types of hydrothermal carbon-based catalysts exhibit excellent microwave absorption performance, facilitating rapid heating of pine particles at a rate as fast as 5.49 °C/s. Among these catalysts, HCM-Co demonstrates the best catalytic performance, efficiently promoting the cleavage of the β-O-4 bond in lignin and achieving a liquid product yield of 38.4 % at 500 °C. The resulting bio-oil is characterized by its richness in phenolic compounds, accounting for 54.9 % of its composition, and partial mitigation of acidity.

Carbon dots@noble metal nanoparticle composites: research progress report.

Carbon dots@noble metal nanoparticle composites are formed by combining carbon dots and metal nanoparticles using various strategies. Carbon dots exhibit a reducing ability and function as stabilisers; consequently, metal-ion solutions can be directly reduced by them to synthesise gold, silver, and gold-silver alloy particles. Carbon dots@gold/silver/gold-silver particle composites have demonstrated the potential for several practical applications owing to their superior properties and simple preparation process. Until now, several review articles have been published to summarise fluorescent carbon dots or noble metal nanomaterials. Compared with metal-free carbon dots, carbon dots@noble metal nanoparticles have a unique morphology and structure, resulting in new physicochemical properties, which allow for sensing, bioimaging, and bacteriostasis applications. Therefore, to promote the effective development of carbon dots@noble metal nanoparticle composites, this paper primarily reviews carbon dots@gold/silver/gold-silver alloy nanoparticle composites for the first time in terms of the following aspects. (1) The synthesis strategies of carbon dots@noble metal nanoparticle composites are outlined. The principle and function of carbon dots in the synthesis strategies are examined. The advantages and disadvantages of these methods and composites are analysed. (2) The characteristics and properties of such composites are described. (3) The applications of these composite materials are summarised. Finally, the potentials and limitations of carbon dots@noble metal nanoparticle composites are discussed, thus laying the foundation for their further development.

Highly dispersed noble metal nanoparticle composites on biomass-derived carbon-based carriers: synthesis, characterization, and catalytic applications.

Precious metal nanoparticles have been widely investigated due to their excellent activity shown in catalysis and sensing. However, how to prepare highly dispersed noble metal nanoparticles to improve the lifetime of catalysts and reduce the cost is still an urgent problem to be solved. In this study, a carbon-based carrier material was prepared by an expansion method and loaded with Pd or Ag nanoparticles on this carbon material to synthesize precious metal nanoparticle composites, which were characterized in detail. The results show that the nanoparticles prepared using this method exhibit superior dispersion. Under the synergistic effect of noble metal nanoparticles and porous carbon carriers, the composites exhibited excellent catalytic degradation of p-nitrophenol and showed excellent sensing performance in the modified hydrogen peroxide sensor electrode. This approach is highly informative for the preparation of nanocomposites in medical and environmental fields.

Hydrogen storage metal-organic frameworks: From design to synthesis

For many years, there has been great interest in metal-organic frameworks, or MOFs. MOFs are a family of crystalline hybrid organic-inorganic compounds made up of strong coordination interactions connecting metal molecules to organic ligands. Due to their vast specific surface area, structural diversity, and adjustable pore size and functionality, they are highly advantageous in a variety of applications, including hydrogen storage. As a result, MOFs have been thoroughly researched. This study examines the drawbacks of traditional hydrogen storage methods before concentrating on MOFs’ potential as a cutting-edge material to get around these issues. The work also illustrates the benefits of MOFs in enhancing hydrogen adsorption performance by examining the synthesis techniques, functionalization tuning strategies, and their use with metal nanoparticle composites. Simultaneously, the significance of fine-tuning the functionalization and optimizing the performance of MOFs is underscored, and their potential to foster hydrogen-based economic growth is anticipated.

(Invited) Controlling Metal Exsolution on Oxides By External Drivers – Role of Elastic Strain and Ion Irradiation

Exsolution is an effective approach to fabricating oxide-supported metal nanoparticle catalysts via phase precipitation out of a host oxide. A fundamental understanding and control of the exsolution kinetics are needed to engineer exsolved nanoparticles to obtain higher catalytic activity toward clean energy and fuel conversion. Since oxygen release via oxygen vacancy formation in the host oxide is behind oxide reduction and metal exsolution, we hypothesize that the kinetics of metal exsolution should depend on the kinetics of oxygen release. In this work, we probe the surface exsolution kinetics both experimentally and theoretically using thin-film perovskite oxide model systems, show its relation to the oxygen evolution kinetics. We also tune defect formation and the resulting metal exsolution, by external drivers including elastic strain and ion irradiation. Using both of these external drivers, we couple to the formation of point defects and defect clusters, that serve as nucleation sites for nanoparticle exsolution. As a result, we can controllably tune size, density, composition and position of the exsolved metal nanoparticles.

Enhancement of Bifunctional Catalytic Performance of G‐C3N4@ Ag Composite by NaBH4 Etching

AbstractHerein, a novel composite of g‐C3N4 and silver nanoparticles(g‐C3N4@Ag) with enhanced bifunctional catalytic activity through chemical etching is reported. A kind of g‐C3N4@Ag composite by one‐pot route, then treated the product with sodium borohydride (NaBH4) solution for a certain time is first synthesized. The property and morphology of the g‐C3N4@Ag composite changed greatly after the treatment. Compared with the pristine g‐C3N4@Ag composite, the NaBH4‐etching endowed g‐C3N4@Ag composite (RACN) with smoother two‐dimensional plane structure, as well as an extension of the conjugate system which originating from the stronger chemical connection between the Ag nanoparticles and g‐C3N4. Furthermore, research results indicated that the RACN showed superior broad‐spectrum catalytic performance for the reduction of aromatic nitro compounds, and the catalytic efficiency of the RACN is enhanced dozens of times by the treatment. Moreover, the photocatalytic activity of the RACN is also greatly improved. This discovery provides an efficient and facile method toward the enhancement of catalytic activity of semiconductor and metal nanoparticle composites by chemical etching.

A SP-ICP-MS protocol for the detection of metal nanoparticles composition and size in tattooed ex vivo human skin explants

We developed and validated a protocol based on Single Particle Inductively Coupled Plasma Mass Spectrometry (SP ICP-MS) to detect composition and size of metal nanoparticles (MNPs) in tattoo inks end ex vivo tattooed human skin explants. The explants were tattooed with different inks using an ordinary tattoo machine. Then, 72 hours after tattooing, skin explants were subjected to alkaline extraction by tetramethylammonium hydroxide solution and MNPs of Ag, Al2O3, Au, Cr2O3, CuO, Fe2O3, TiO2 and ZnO were analysed for particle composition and size by SP ICP-MS. The method was validated by assessing the limit of detection, accuracy, precision, and size stability over 72 hours. Particles of Al2O3, Cr2O3, CuO, Fe2O3, TiO2 and ZnO were observed in human skin in the range from 27 nm to 153 nm, and from 26 nm to 228 nm in tattoo inks. Ag and Au NPs were not found neither in inks nor in the skin. Advantages of the protocol were the ability to simultaneously detect the composition of particles and their size, the straightforward sample preparation, the high sensitivity and precision, and the speed of execution of the analysis. The developed methodology can be applied to skin exposed to other consumer products topically applied, such as sunscreens, cosmetics, personal care products and medical devices, which can be all sources of MNPs, in order to improve knowledge and support the human exposure assessment process.

Green synthesized nano-silver/cellulose aerogel as a robust active and recyclable catalyst towards nitrophenol hydrogenation

Water contamination by hazardous aromatic nitro compounds is a serious problem, and reduction in p-nitrophenol (PNP) by combining a catalyst and a reductant has been a topic of intense interest in recent years. Although several methods have been explored for generating effective metal nanoparticle composites, the nano-size makes it challenging to recover after wastewater treatment, thus restricting its practical use. Additionally, the previously described approaches had critical disadvantages, including high material synthesis costs and secondary environmental contamination. Herein, nontoxic and low-cost materials were employed. A novel green technique for the synthesis of silver nanoparticles (AgNPs) decorated on 3D cellulose aerogel (CA) derived from water hyacinth was demonstrated using an aqueous extract ofJasminum subtriplinerve Blumeleaves as a stabilising and reducing agent for high-performance towards PNP reduction in the presence of NaBH4 in an aqueous medium. The as-prepared composites were investigated by powder X-ray diffraction, scanning electron microscopy with energy-dispersive spectroscopy, high-resolution transmission electron microscopy, Fourier transform infrared spectroscopy and Raman spectroscopy. Batch experiments of PNP hydrogenation were conducted to evaluate the catalytic performance. At room temperature, the reaction could be completed in about 10 min using the 1.5Ag/CA2.0 catalyst, with the catalytic activity almost unchanged. Moreover, the structure has no apparent deterioration after five cycles. Strikingly, the 26.15 nm-average size of AgNPs with even distribution on CA correlates with the good kinetic characterisation/feature (k = 0.34 min−1). In particular, the reduction rates of the three isomers of nitrophenol were examined and found to follow the following order: PNP > o-nitrophenol (ONP) > m-nitrophenol (MNP). This study provides some valuable insights into developing easily separated robust green catalysts for heterogeneous catalytic reactions in the environmental remediation field.

Development of Silicon Nanowire Array–Metal Hybrid Catalysts for Batch and Flow Organic Reactions

AbstractThe development of highly efficient and reusable supported metal catalysts is important for academic and industrial synthetic organic chemistry; however, their widespread application remains a challenge because supported Pd, Rh, and Pt catalysts are expensive. To overcome these problems, we have developed novel, highly stable, reusable, and selective heterogeneous catalysts consisting of silicon nanowire arrays (SiNAs) and metal nanoparticle composites. Metal nanoparticles on SiNA have been applied as heterogeneous catalysts in the Mizoroki–Heck reaction, C–H arylation, hydrosilylation, hydrogenation, reductive alkylation of amines, and hydrogenative decarboxylation of fatty acids. The catalysts used in this study showed high catalytic activity in batch and microflow conditions. Their structural investigation using X-ray Photoelectron Spectroscopy (XPS) suggests that strong metallic bonding (alloy/agglomeration) between the metal and silicon (metal silicide bond formation) is key to the high catalyst stability.1 Introduction2 Development of Silicon Nanowire Array (SiNA) Hybrid Catalysts and Silicon Nanostructure (SiNS) Hybrid Catalysts3 Application of SiNA-Pd to Organic Synthesis4 SINA-Supported Mono- and Bimetallic Nanoparticles for Hydrogenation Reactions5 Application of SiNA-Pd to Microflow Reductive Alkylation Reactions6 Application of SiNA-Rh to Hydrogenative Decarboxylation Reactions using Microwave Irradiation7 Conclusions

Synthesis and Spectroscopic Characterization of Zinc Sulphide nanoparticles using Microwave irradiation of Zinc complex of Thiosemicarbazone ligand as a Single Molecular precursor : Pharmacological activities

Single molecular precursors are appropriate starting materials for synthesis of semiconductor nanoparticles (NPs), which allow for the control of atomic ratio, monodispersity, composition and particle size of nanoscaled metallic sulfide nanoparticles. In the present study, we have reported the synthesis of nanostructured chalcogenides pharmacologically active active zinc sulfide nanoparticles (ZnS NPs) using Zn (II) ion inserted thiosemicarbazone ligand as a single molecular precursor .The precursors were thermally pyrolysized using high energy microwave radiations to obtain very fine ZnS nanoparticles. In this synthesis, we use DMSO as a nonpolar solvent for the synthesis of all compounds. The heating of Zinc complex in the non- aqueous environment of DMSO plays a very crucial role in decreasing reaction time, reducing the chances of side reactions and proper conversion of Zn complex into ZnS nanoparticles. In this reaction Zn complex of thiosemicarbazone ligand provides both Zn2+ and S2- ions for synthesis of ZnS nanoparticles. The microwave synthesis of ZnS NPs from Zn complex is a very simple, fast, highly effective, efficient and low cost method. All synthesized compounds were characterized by various structural, electronic, vibrational, optical, morphological and pharmacological characterizations. The prepared ZnS NPs were found to crystallize in cubic phase, which generally forms at low temperatures, with the dimensions dependent upon the molar ratio of molecular precursors used. Synthesized ZnS nanomaterials had surface sulfur vacancies that extend their absorption spectra towards the visible region and decreased the bond gap. This allowed ZnS nanoparticles to demonstrate various pharmacological activities like antibacterial, antioxidant and anti-inflammatory activities under normal conditions. Powered X-ray diffraction studies confirms the formation of well -defined equispaced crystalline ZnS NPS. TEM and FE SEM microscopic studies confirmed the elongated tubules structure of ZnS NPs with an average particle size of 60 nm. Sharpe electronic absorption band at 390 nm indicates the synthesis of good quality ZnS NPs. The FT-IR spectral studies confirmed the presence of Zn-S stretching, N-H bending and C=N stretching, vibrations in molecular precursor as Zn(II) complex. The thermal analysis of molecular precursor was performed to investigate the thermal stability of zinc complex. The Zn complex was stable up-to 3800 c. All synthesized compounds demonstrated excellent pharmacological activities like antibacterial, antioxidant and antiinflammatory activities as compared to standards used in analysis of compounds. The microwave synthesis of ZnS nanoparticles via single molecular precursor in proper stoichiometric ratios is an excellent and an efficient method for synthesizing highly effective bioactive agents which can be considered as good drug candidate for the treatment of various diseases in future

A facile and sustainable approach for the preparation of Pd/ZIF-8 nearly without waste emission

ZIF-8 supported metal nanoparticle composites (MNPs/ZIF-8) receive great interest for their versatile applications. However, the preparation of MNPs/ZIF-8 is inevitable to produce liquid and solid wastes, which are a constant headache for industrial production. This work presents a facile and sustainable approach to prepare Pd/ZIF-8 composite by directly reacting the PdO/ZnO with 2-methylimzadole in H2 atmosphere. The developed approach is a solvent-free process and uses H2 as the reducing agent, it dramatically reduced the liquid and solid wastes emission. Meanwhile, the method allows the reduction of Pd NPs and the building of ZIF-8 by one pot, significantly simplifying the preparation process. Moreover, the as-prepared Pd/ZIF-8 shows a good catalytic activity for the hydrogenation of styrene.

Metal nanoparticles and nanoparticle composites are effective against Haemophilus influenzae, Streptococcus pneumoniae, and multidrug-resistant bacteria.

Treatment for lower respiratory tract infection caused by multidrug-resistant organisms (MDRO) are often limited. This study explored the activity of different metal nanoparticles against several respiratory pathogens including MDROs. Clinical isolates of carbapenem-resistant Acinetobacter baumannii (CRAB), carbapenem-resistant Klebsiella pneumoniae (CRKP), Pseudomonas aeruginosa, Haemophilus influenzae, methicillin-resistant Staphylococcus aureus (MRSA), and Streptococcus pneumoniae were tested for invitro susceptibilities to various antibiotics and nanoparticles. Minimum inhibitory concentrations (MICs) of silver-nanoparticle (Ag-NP), selenium-nanoparticle (Se-NP), and three composites solutions ND50, NK99, and TPNT1 (contained 5ppm Ag-NP, 60ppm ZnO-nanoparticle, and different concentrations of gold-nanoparticle or ClO2) were determined by broth microdilution method. Fifty isolates of each bacterial species listed above were tested. Ag-NP showed lower MICs to all species than Se-NP. The MIC50s of Ag-NP for CRAB, CRKP, P. aeruginosa, and H. influenzae were <3.125ppm, 25ppm, <3.125ppm, and <3.125ppm, respectively, while those for S. pneumoniae and MRSA were >50ppm and 50ppm. Among CRAB, CRKP and P. aeruginosa, the MIC50s of ND50, NK99, and TPNT1 for CRAB were the lowest (1/8 dilution, 1/8 dilution, and 1/8 dilution, respectively), and those for CRKP (>1/2 dilution, 1/2 dilution, and 1/2 dilution, respectively) were the highest. Both MRSA and S. pneumoniae showed high MIC50s to ND50, NK99, and TPNT1. Metal nanoparticles had good invitro activity against Gram-negative bacteria. They might be suitable to be prepared as environmental disinfectants or inhaled agents to inhibit the growth of MDR Gram-negative colonizers in the lower respiratory tracts of patients with chronic lung diseases.

(Nanocarbons Division Richard E. Smalley Research Award) Evolution of Nanocarbons in Energy Conversion and Storage

The discovery of fullerenes led to the exploration of their excited state and electron storage properties in 1990s. This wave of research quickly led to the growth of carbon nanotube research, followed by graphene based nanocarbon materials. After a span of more than three decades, we now have a better understanding of properties of these nanocarbons and how to utilize them in various applications. Of particular interest are graphene–semiconductor or −metal nanoparticle composites with the capability to function as efficient, multifunctional materials for energy conversion and storage. In particular, reduced graphene oxide (RGO) is a suitable composite substrate because of its two-dimensional structure, outstanding surface area, and electrical conductivity. The presentation will focus on common employed methods to design graphene oxide-semiconductor composite materials and examine key studies that characterize their excited state interactions. The favorable energetics of RGO for intercepting excited states and inducing charge separation, along with the ease of developing electrode materials with tailored properties make it an exceptionally important mediator for improving the performance of solar cells and photocatalyst arrays. Strategies to develop graphene composites and control electron capture and transport through the 2D carbon network will be discussed.

A Review on Electrospun PVDF-Metal Nanoparticle Composites for Electronic Applications

In this review, we have discussed on the latest development in metal nanoparticle composites based on PVDF via electrospinning process for electronic applications. Human robotics, wireless-data communication, nanogenerators, wearable biocompatible/bio-inspirable sensors, motion detectors, and actuators have become a key component in self-powered IoT devices. Due to the power demand, an urge is in the industry for fabricating portable, flexible, and sustainable green micro and nano devices. PVDF and its copolymers have attracted greater attention because of their excellent piezoelectric, dielectric, magnetic, and good mechanical properties, suitable for lightweight application and due to the biocompatible nature. Piezoelectric property can be enhanced with the addition of different metal nanoparticles and can be used for various application like sensor, actuators, energy harvesters, health monitors, EMI shielding. Interesting results reported by many research groups working in this field is consolidated in this review paper.

Fine Tuning the Optical Properties of Single Au Nanoparticles by Plasmon‐Driven Growth in Closed‐Loop Control

AbstractThe morphology and composition of metallic nanoparticles (NPs) determine their optical response, so finely controlling them at the single particle level is the key to achieve tailored functionalities. Here, the control of plasmon‐driven growth of Au NPs is studied by live monitoring their photoluminescence emission in a closed‐loop. It is found that the final emission maximum of single NPs can be tuned between 550 and 580 nm with a precision of 2–3 nm, and that the tuning is also reflected in their scattering maximum. In comparison to controlling the growth by irradiation time and/or reaction conditions, the closed‐loop control delivers superior reproducibility and a three to fourfold higher precision in the final properties of the NPs.

Catalyst development for viability of electrochemical hydrogen purifier and compressor (EHPC) technology

Considering the disadvantages of conventional compressors, which are widely used in the world, it is thought that the electrochemical hydrogen purifier and compressor system (EHPC) to be developed will provide great advantages in hydrogen technologies. The electrocatalyst, which is one of the main components of the EHPC system, is critical for both the performance and applicability of the system. In this study, commercial carbon black supported Pt and Pd containing catalysts were prepared for the EHPC system by using microwave heating method. The synthesized catalysts were mono and bimetallic and were named as Pt/C, Pd/C and PtPd/C, respectively. By characterizing the prepared catalysts with ICP-MS, SEM-EDS, TEM, XRD and XPS, information about the distribution, amount, morphology and composition of metal nanoparticles on the support material was obtained. In addition, electrochemical properties of the catalysts were determined by CV analysis. The physical characterization results revealed that the catalysts were successfully synthesized by microwave method and that different ratios of metals and bimetallic could be loaded on the support material. It was also seen that the electrochemical activity of the PtPd/C bimetallic catalyst was better than the others.

Reduction of metal nanoparticle decorated flexible graphene oxide by laser at various temperatures and under selected atmospheres

In situ Raman spectroscopy of flexible films of bare graphene oxide (GO) and GO decorated with Pt and Au nanoparticles (NPs) were examined upon exposure to synthetic air and 1% hydrogen in synthetic air. Initially, GO possesses an sp2 rich-structure at room temperature; however, it suffers from a drastic sp2 loss at higher temperatures under argon laser exposure leading to structural damage above 65 °C. Conversely, metal nano particle (MNP) decorated GO undergoes a drastic reduction of sp2 content mainly due to an increased defect density. In MNP composites, the formation rate of reduced graphene oxide (rGO) elevates at higher temperatures leading to an improvement in the sp2 fraction to some extent under argon laser exposure. In fact, the optical properties of MNP decorated GO drastically change against those of bare GO. Despite Pt NPs demonstrating a large catalytic effect with temperature, Au NPs do not. Similarly, the catalytic effect of Pt-GO gives rise to a slight excess in rGO formation in favor of the sp2 domain recovery. Here, there is a dominant temperature effect and a minor catalytic effect during laser exposure to GO.