Plasmon-mediated electrocatalysis based on plasmonic gold nanoparticles (Au NPs) has emerged as a promising approach to facilitate electrochemical reactions with the introduction of light to excite the plasmonic electrodes. We have investigated the electrochemical oxidation of 4-(hydroxymethyl)benzoic acid (4-HMBA) on gold (Au), nickel (Ni), and platinum (Pt) metal working electrodes in alkaline electrolytes. Au has the lowest onset potential for catalyzing the electrooxidation of 4-HMBA among the three metals in base, whereas Pt does not catalyze the electrooxidation of 4-HMBA under alkaline conditions, although it is conventionally a good electrocatalyst for alcohol oxidation. Both 4-carboxybenzaldehyde and terephthalic acid are detected as the products of electrochemical oxidation of 4-HMBA on the Au working electrode by high-performance liquid chromatography . The electrodeposited Au NPs on indium tin oxide (ITO)-coated glass is further utilized as the working electrode for the 4-HMBA electrooxidation. With its broad absorption in the visible and near-infrared range, we show that the Au NPs on the ITO electrode could enhance the electrochemical oxidation of 4-HMBA under green and red LED light illuminations (505 and 625 nm). A possible reaction mechanism is proposed for the electrochemical oxidation of 4-HMBA on Au working electrodes in an alkaline electrolyte.
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Plasmonic Response of Light-Activated, Nano-Gold Doped Polymers
Abstract Incorporation of metallic nanoparticles (NPs) in polymer matrix has been used to enhance and control dissolution and release of drugs, for targeted drug delivery, as antimicrobial agents, localized heat sources, and for unique optoelectronic applications. Gold NPs in particular exhibit a plasmonic response that has been utilized for photothermal energy conversion. Because plasmonic nanoparticles typically exhibit a plasmon resonance frequency similar to the visible light spectrum, they present as good candidates for direct photothermal conversion with enhanced solar thermal efficiency in these wavelengths. In our work, we have incorporated ∼3-nm-diameter colloidal gold (Au c ) NPs into electrospun polyethylene glycol (PEG) fibers to utilize the nanoparticle plasmonic response for localized heating and melting of the polymer to release medical treatment. Au c and Au c in PEG (PEG+Au c ) both exhibited a minimum reflectivity at 522 nm or approximately green wavelengths of light under ultraviolet-visible (UV-Vis) spectroscopy. PEG+Au c ES fibers revealed a blue shift in minimum reflectivity at 504 nm. UV-Vis spectra were used to calculate the theoretical efficiency enhancement of PEG+Au c versus PEG alone, finding an approximate increase of 10 % under broad spectrum white light interrogation, and ∼14 % when illuminated with green light. Au c enhanced polymers were ES directly onto resistance temperature detectors and interrogated with green laser light so that temperature change could be recorded. Results showed a maximum increase of 8.9 °C. To further understand how gold nanomaterials effect the complex optical properties of our materials, spectroscopic ellipsometry was used. Using spectroscopic ellipsometry and modeling with CompleteEASE® software, the complex optical constants of our materials were determined. The complex optical constant n (index of refraction) provided us with optical density properties related to light wavelength divided by velocity, and k (extinction coefficient) was used to show the absorptive properties of the materials.
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- Award ID(s):
- 1757351
- PAR ID:
- 10158959
- Date Published:
- Journal Name:
- MRS Advances
- Volume:
- 4
- Issue:
- 31-32
- ISSN:
- 2059-8521
- Page Range / eLocation ID:
- 1749 to 1758
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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This article belongs to the Special Issue Synthesis and Applications of Gold Nanoparticles) Rodolphe Antoine (Ed.)more » « less
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Protein-functionalized nanoparticles introduce a potentially novel drug delivery method for medical therapeutics, including involvement in cancer therapies and as contrast agents in imaging. Gold and silver nanoparticles are of particular interest due to their distinctive properties. Extensive research shows that gold nanoparticles demonstrate incredible photothermal properties and non-toxic behavior, while silver nanoparticles exhibit antibacterial properties but increase toxicity for human use. However, little is known regarding the properties or applications of hybrid silver-gold particles. This study measured the UV-Vis absorbance spectrum for 40 nm diameter Au, streptavidin-conjugated Au, Ag@Au hybrid, Ag nanoparticles, and Transient Absorbance Spectra of Au. Analysis indicates that the hybrid particles exhibit characteristics of both Ag and Au particles, implying potential applications similar to both Ag and Au nanoparticles.more » « less
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1557/adv.2019.286
