Wael H. Eisa

Bio: Wael H. Eisa is an academic researcher from North Carolina State University. The author has contributed to research in topics: Silver nanoparticle & Fourier transform infrared spectroscopy. The author has an hindex of 23, co-authored 42 publications receiving 1397 citations.

Solid-State Synthesis of Metal Nanoparticles Supported on Cellulose Nanocrystals and Their Catalytic Activity

Abstract: Heterogeneous catalysis has played a critical role in environmental remediation, for example, in processes that generate toxic streams. Thus, there is an ever-increasing need for green, cost-effective routes to synthesize highly active catalysts. In this study, a cellulose nanomaterial (cellulose nanocrystals, CNC) was employed as solid support for the nucleation of silver and gold nanoparticles via solid-state synthesis. The process involved solvent-free reduction in ambient conditions of metal precursors on the surface of CNC and in the presence of ascorbic acid. Surface plasmon resonance and X-ray diffraction indicated the successful formation of the metal nanoparticles, in the form of organic–inorganic hybrids. A strong hydrogen bonding was observed between CNC and the metal nanoparticles owing to the high density of hydroxyl groups in CNC, as determined by Fourier transform infrared spectroscopy. Electron microscopies indicated that the silver and gold precursors formed nanoparticles of hexagonal and...

Comparative spectral and shielding studies of binary borate glasses with the heavy metal oxides SrO, CdO, BaO, PbO or Bi2O3 before and after gamma irradiation

Abstract: This work aims to compare the experimental shielding behavior of some prepared binary borate glasses with SrO, CdO, BaO, PbO or Bi2O3 towards successive gamma irradiation by investigating their combined optical and FTIR spectral measurements before and after gamma irradiation. Optical spectra of all the samples reveal strong UV absorption which is related to the presence of unavoidable trace iron impurities (Fe3 + ions) contaminated within the raw materials which were used for the preparation of the studied glasses. Additional near visible bands are observed in the two lead borate and bismuth borate glasses due to characteristic absorption of Pb2 + and Bi3 + ions. Gamma irradiation causes varying responses depending on the type of glass. Bismuth borate glass shows highly marked shielding towards successive gamma irradiation while lead borate glass reveals resistance in low dose (4 Mrad) and produces induced defects at high dose (8 Mrad). The other glasses show obvious generation of induced defects upon gamma irradiation. FTIR spectra of the glasses reveal vibrational modes characteristic to combined presence of triangular and tetrahedral borate units in their specific different wavenumbers besides the presence of interfering structural Pb O and Bi O linkages in the lead borate and bismuth borate glasses. Gamma irradiation produces limited changes in the FTIR spectra specifically the intensity of some vibrational modes while the bismuth borate glass has proved to be the best radiation-shielding candidate when comparing the combined spectral results after successive gamma irradiation.

‘Green’ synthesis of metals and their oxide nanoparticles: applications for environmental remediation

Abstract: In materials science, “green” synthesis has gained extensive attention as a reliable, sustainable, and eco-friendly protocol for synthesizing a wide range of materials/nanomaterials including metal/metal oxides nanomaterials, hybrid materials, and bioinspired materials. As such, green synthesis is regarded as an important tool to reduce the destructive effects associated with the traditional methods of synthesis for nanoparticles commonly utilized in laboratory and industry. In this review, we summarized the fundamental processes and mechanisms of “green” synthesis approaches, especially for metal and metal oxide [e.g., gold (Au), silver (Ag), copper oxide (CuO), and zinc oxide (ZnO)] nanoparticles using natural extracts. Importantly, we explored the role of biological components, essential phytochemicals (e.g., flavonoids, alkaloids, terpenoids, amides, and aldehydes) as reducing agents and solvent systems. The stability/toxicity of nanoparticles and the associated surface engineering techniques for achieving biocompatibility are also discussed. Finally, we covered applications of such synthesized products to environmental remediation in terms of antimicrobial activity, catalytic activity, removal of pollutants dyes, and heavy metal ion sensing.

"Green" nanotechnologies: synthesis of metal nanoparticles using plants

Abstract: While metal nanoparticles are being increasingly used in many sectors of the economy, there is growing interest in the biological and environmental safety of their production. The main methods for nanoparticle production are chemical and physical approaches that are often costly and potentially harmful to the environment. The present review is devoted to the possibility of metal nanoparticle synthesis using plant extracts. This approach has been actively pursued in recent years as an alternative, efficient, inexpensive, and environmentally safe method for producing nanoparticles with specified properties. This review provides a detailed analysis of the various factors affecting the morphology, size, and yield of metal nanoparticles. The main focus is on the role of the natural plant biomolecules involved in the bioreduction of metal salts during the nanoparticle synthesis. Examples of effective use of exogenous biomatrices (peptides, proteins, and viral particles) to obtain nanoparticles in plant extracts are discussed.

Laser Synthesis and Processing of Colloids: Fundamentals and Applications

Abstract: Driven by functionality and purity demand for applications of inorganic nanoparticle colloids in optics, biology, and energy, their surface chemistry has become a topic of intensive research interest. Consequently, ligand-free colloids are ideal reference materials for evaluating the effects of surface adsorbates from the initial state for application-oriented nanointegration purposes. After two decades of development, laser synthesis and processing of colloids (LSPC) has emerged as a convenient and scalable technique for the synthesis of ligand-free nanomaterials in sealed environments. In addition to the high-purity surface of LSPC-generated nanoparticles, other strengths of LSPC include its high throughput, convenience for preparing alloys or series of doped nanomaterials, and its continuous operation mode, suitable for downstream processing. Unscreened surface charge of LSPC-synthesized colloids is the key to achieving colloidal stability and high affinity to biomolecules as well as support materials,...

Recent Development of Carbon Nanotube Transparent Conductive Films

Abstract: Transparent conducting films (TCFs) are a critical component in many personal electronic devices. Transparent and conductive doped metal oxides are widely used in industry due to their excellent optoelectronic properties as well as the mature understanding of their production and handling. However, they are not compatible with future flexible electronics developments where large-scale production will likely involve roll-to-roll manufacturing. Recent studies have shown that carbon nanotubes provide unique chemical, physical, and optoelectronic properties, making them an important alternative to doped metal oxides. This Review provides a comprehensive analysis of carbon nanotube transparent conductive films covering detailed fabrication methods including patterning of the films, chemical doping effects, and hybridization with other materials. There is a focus on optoelectronic properties of the films and potential in applications such as photovoltaics, touch panels, liquid crystal displays, and organic light-emitting diodes in conjunction with a critical analysis of both the merits and shortcomings of carbon nanotube transparent conductive films.