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Photocatalytic degradation of acetaminophen over Ag, Au and Pt loaded TiO2 using solar light
摘要： The sustainability and feasibility of using solar irradiation instead of UV light in photocatalysis is a promising approach for water remediation. In this study, photocatalytic degradation (PCD) of a widely used analgesic and antipyretic drug, acetaminophen (AP), with noble metal loaded TiO2 photocatalysts (Ag/TiO2, Au/TiO2 and Pt/TiO2) was investigated in aqueous suspension using solar light. The deposition of noble metals (Ag, Au and Pt) onto the TiO2 surface enhanced the PCD of AP under different operating conditions including pH, surfactants and drug excipients. However, lower degradation rate constants of AP were obtained under simulated and direct solar light as compared to UV light. The degradation mechanism of AP under UV as well as simulated solar light was found to follow similar, though not identical, reaction pathways leading to hydroxylated intermediates (e.g. 4-acetamidoresorcinol (4-AR), 4-acetamidocatechol (4-AC) and hydroquinone (HQ)) through competitive routes. The PCD of AP followed a pseudo first order kinetics according to Langmiur-Hinshelwood model. Noble metal (Ag, Au and Pt) loaded TiO2 photocatalysts can be used effectively to degrade AP in water under both solar and UV light.
关键词： Solar light,Hydroxyl radical,Noble metal,Acetaminophen,TiO2
更新于2025-09-19 17:15:36
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Optical absorption in complexes of abasic DNA with noble-metal nanoclusters by first principles calculations
摘要： Optical absorption in complexes of abasic DNA with noble-metal nanoclusters by first principles calculations. Abasic sites (AP site) in a DNA duplex have been experimentally used to produce fluorescent Ag nanoclusters (NC) with a small number of atoms (n ≤ 6). These AP-DNA:NC complexes act as biological markers that help to locate genes associated with diseases related to single nucleotide polymorphisms (SNP), for example. Abasic sites are the most common SNP genetic variation, and their detection may help predict a host of genetically determined diseases. In this work, we report a theoretical study of the optical absorption spectra of AP-DNA:Ag4 and AP-DNA:Au4 complexes using a fully ab initio methodology. We consider several different base environments for the noble-metal nanocluster occupying the AP site, and compute the absorption spectra of sixteen AP-DNA:Ag4 and sixteen AP-DNA:Au4 complexes. We find that optical absorption in the AP-DNA:Ag4 complexes tends to concentrate in the green-to-violet range of frequencies (2.50 eV ≤ ?ω ≤ 3.2 eV) and that AP-DNA:Au4 complexes display absorption peaks in the violet-to-ultraviolet interval (?ω ≥ 3.0 eV). An analysis of the optical absorption mechanisms in these AP-DNA:NC complexes shows that they can be of local, charge-transfer, or hybrid nature, i.e., AP-DNA:NC complexes display the full variety of optical absorption processes in molecular systems. In particular, we identify both charge-transfer and hybrid processes involving several DNA bases surrounding the NC. Importantly, we find that even sequences where the Ag4 cluster is not in a guanine rich neighborhood display absorption peaks in the visible-light spectrum. Moreover, we obtain that the maximum intensities of the absorption peaks in complexes with pyrimidine vacancies are generally higher than those in complexes with purine vacancies. Regarding the selectivity of single-vacancy AP-DNA to specific noble-metal nanocluster sizes, our calculations show that the four-atom Ag4 (Au4) species fits naturally and binds into the AP-site in a single-vacancy AP-DNA.
关键词： noble-metal nanoclusters,optical absorption,first principles calculations,abasic DNA,Au4,charge-transfer,hybrid processes,Ag4
更新于2025-09-19 17:15:36
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Ultrafast Laser Manufacture of Stable, Efficient Ultrafine Noble Metal Catalysts Mediated with MOF Derived High Density Defective Metal Oxides
摘要： Supported metal nanoparticles (MNPs) undergo severe aggregation, especially when the interaction between MNPs and their supports are limited and weak where their performance deteriorates dramatically. This becomes more severe when catalysts are operated under high temperature. Here, it is reported that MNPs including Pt, Au, Rh, and Ru, with sub-2 nm size can be stabilized on densely packed defective CeO2 nanoparticles with sub-5 nm size via strong coupling by direct laser conversion of corresponding metal ions encapsulated cerous metal–organic frameworks (Ce-MOFs). Ce-MOF serves as an ideal dispersion precursor to uniformly encapsulate noble metal ions in their orderly arranged pores. Ultrafast laser vaporization and cooling forms uniform, ultra-small, well-mixed, and exceptionally dense nanoparticles of metal and metal oxide concurrently. The laser-induced ultrafast reaction (within tens of nanoseconds) facilitates the precipitation of CeO2 nanoparticles with abundant surficial defects. Due to the well-mixed ultrasmall Pt and CeO2 components with strong coupling, this catalyst exhibits exceptionally high stability and activity both at low and high temperatures (170–1100 °C) for CO oxidation in long-term operation, significantly exceeding catalysts prepared by traditional methods. The scalable feature of laser and huge MOF family make it a versatile method for the production of MNP-based nanocomposites in wide applications.
关键词： noble metal catalysts,lasers,metal oxides,defects,metal–organic frameworks
更新于2025-09-19 17:13:59
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Laser-Induced Optoacoustic Spectroscopy Studies of Inorganic Functionalized Metallic Nanorods
摘要： Plasmonic nanoparticles can be used in photothermal therapy thanks to their ability to generate local heat. The light-to-heat conversion efficiency is crucial for therapeutic and diagnostic applications. The photothermal properties of gold nanorods functionalized with silica layers of controllable thickness were characterized using both theoretical and experimental approaches. The time-resolved laser-induced optoacoustic spectroscopy (LIOAS) was used to determine the amount of absorbed energy changed promptly into heat. The heat generation efficiencies were simulated by the means of finite integration technique. The obtained parameters were correlated with silica thickness. Experimental results are consistent with theoretical predictions, thus LIOAS is a unique reliable method for studying photothermal effect in gold nanoparticles.
关键词： noble metal nanoparticles,finite integration technique,laser-induced optoacoustic spectroscopy,surface plasmon resonance,photothermal effect
更新于2025-09-19 17:13:59
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Plasmonic Molybdenum Tungsten Oxide Hybrid with Surface-Enhanced Raman Scattering Comparable to that of Noble Metals
摘要： The Surface-enhanced Raman Scattering (SERS) research is in full swing owing to its high sensitivity and high selectivity, however, the substrate with a superexcellent performance for SERS is largely confined to noble metals (Au and Ag, etc.). Although the SERS active substrate has been extended to semiconductor and transition metal, it is frustrating that their sensitivity is insufficient for widespread practical application. Here we report the plasmonic molybdenum tungsten oxide hybrid (MWO) nanomaterials (NMs) which can be used as a high-performance substrate with noble metal-comparable SERS. MWO NMs can achieve the trace detection of rhodamine 6G (R6G), basic fuchsin (BF), and oil red O (ORO). The detection limit concentration for R6G is 10-8 M with the maximum enhancement factor is up to 6.09×107. The superexcellent SERS performance was put down to the cooperative enhancement effect of electromagnetic enhancement mechanism (EM) and the charge transfer mechanism (CT). Moreover, in the proposed system, the EM and CT contribution was distinguished by employing the PVP, which serves as a barrier layer to prevent the CT process from MWO NMs to R6G. This remarkable MWO NMs can be obtained with a facile method and this research shows a new insight on the non-noble metal-based SERS substrate.
关键词： Molybdenum tungsten oxide hybrid,R6G,Noble metal-comparable,SERS,Plasmonic
更新于2025-09-19 17:13:59
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Controlled Fabrication of Optical Signal Input/Output Sites on Plasmonic Nanowires
摘要： Silver nanowires have attracted considerable attention as sub-diffraction limited diameter waveguides in a variety of applications including cell endoscopy and photonic integrated circuitry. Optical signal transport occurs by coupling light into propagating surface plasmons which scatter back into light further along the wire. However these inter-conversions only occur efficiently at wire ends, or at defects along the wire, which are not controlled during synthesis. Here we overcome this limitation, demonstrating the visible laser light-induced fabrication of gold nanostructures at desired positions on silver nanowires, and their utility as efficient in/out coupling points for light. The gold nanostructures grow via plasmon-induced reduction of Au(III) and are shown to be excellent ‘hotspots’ for surface-enhanced Raman scattering.
关键词： optical antenna,surface enhanced Raman scattering,Chemically synthesized noble metal nanowires,gold nanoparticle,laser direct writing
更新于2025-09-19 17:13:59
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Analysis and simulation of a plasmonic biosensor for hemoglobin concentration detection using noble metal nano-particles resonances
摘要： In this paper, three different shapes (sphere, cubic, and cylinder) silver plasmonic nano-particles for the detection of hemoglobin concentration in blood is analyzed. This work is done to determine the hemoglobin concentration in blood using a sensing feature by changing hemoglobin concentration from 0 to 140g/l. The impact of hemoglobin concentration on refractive index changes in the surrounding medium of nano-particles is considered. Simulated results show that, scattering cross-section has a sharp peak for cubic nano-particles with the full width at half maximum (FWHM) of 50nm. FWHM is 64nm and 94nm for sphere and cylinder nanoparticles, respectively. Exactly, after applying the hemoglobin refractive index in each concentration to the surrounding medium, an increase in resonance wavelength in extinction cross-section is obtained. The wavelength shifts of 3.3nm, 3.7nm, and 5.5nm are obtained for hemoglobin concentration of 140g/l using sphere, cubic, and cylinder shapes nano-particles, respectively. Further, changing the simulated structure parameters can manage the plasmonic resonance wavelength and it is applicable to detect other biological samples.
关键词： hemoglobin detection,Plasmonic biosensor,Surface plasmon resonance,extinction cross-section,noble metal
更新于2025-09-16 10:30:52
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MXenes induce epitaxial growth of size-controlled noble nanometals: a case study for surface enhanced Raman scattering (SERS)
摘要： Noble nanometals are of significance in both scientific interest and technological applications, which are usually obtained by conventional wet-chemical synthesis. Organic surfactants are always used in the synthesis to prevent unexpected overgrowth and aggregation of noble nanometals. However, the surfactants are hard to remove and may interfere with plasmonic and catalytic studies, remaining surfactant-free synthesis of noble nanometals a challenge. Herein, we report an approach to epitaxial growth of size-controlled noble nanometals on MXenes. As piloted by density functional theory calculations, along with work function experimental determination, kinetic and spectroscopic studies, epitaxial growth of noble nanometals is initiated via a mechanism that involves an in situ redox reaction. In the redox, MXenes as two-dimensional solid reductants whose work functions are compatible with the reduction potentials of noble metal cations, enable spontaneous donation of electrons from the MXenes to noble metal cations and reduce the cations into nanoscale metallic metals on the outmost surface of MXenes. Neither surfactants nor external reductants are used during the whole synthesis process, which addresses a long-standing interference issue of surfactant and external reductant in the conventional wet-chemical synthesis. Moreover, noble nanometals are size-controlled. Impressively, noble nanometals firmly anchored on MXenes exhibit excellent performance towards surface enhanced Raman scattering. Our developed strategy will promote the nanostructure-controlled synthesis of noble nanometals, offering new opportunities to further improve advanced functional properties towards practical applications.
关键词： SERS,Two-dimensional materials,MXene,In situ redox,Noble metal
更新于2025-09-12 10:27:22
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Copper nanoparticles obtained by laser ablation in liquids as bactericidal agent for dental applications
摘要： The dramatic increase of antibiotic-resistant bacteria is considered one of the greatest threats to human health at global scale. The antibacterial activity of noble metal nanoparticles, could be the solution against bacterial infectious diseases which currently do not respond to conventional treatments. In this work, copper nanoparticles were produced by laser ablation using two different lasers. A nanosecond laser operating at 532nm and a picosecond laser at 1064nm were used to ablate a copper target submerged in water and methyl alcohol. The obtained colloidal solutions consisted of copper oxide nanoparticles in suspension with diameters ranging from few nanometers to 45 nm. The nanoparticles formation process is highly influenced by laser parameters, but the solvent plays a crucial role on their characteristics. Cu oxide nanoparticles obtained in water present chain-like nanostructure, while those obtained in methyl alcohol are spherical with lower presence of oxide. All the obtained nanoparticles are crystalline and noticeably stable. Microbiology confirm their strong activity against Aggregatibacter actinomycetemcomitans. Cytocompatibility with human periodontal ligament stem cells is also confirmed. The biological assays evidence that ions release is not the main parameter responsible for the bactericidal activity of copper nanoparticles. Other factors such as oxidation state, size and crystallographic structure, have a greater influence on the process.
关键词： noble metal nanoparticles,laser ablation,copper nanoparticles,antibacterial effect
更新于2025-09-12 10:27:22
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Alternative electrodes for HTMs and noble-metal-free perovskite solar cells: 2D MXenes electrodes
摘要： The high cost of hole transporting materials (HTMs) and noble metal electrodes limits the application of perovskite solar cells (PSCs). Carbon materials have been commonly utilized for HTMs and noble-metal-free PSCs. In this paper, a more conductive 2D MXene material (Ti3C2), showing a similar energy level to carbon materials, has been used as a back electrode in HTMs and noble-metal-free PSCs for the ?rst time. Seamless interfacial contact between the perovskite layer and Ti3C2 material was obtained using a simple hot-pressing method. After the adjustment of key parameters, the PSCs based on the Ti3C2 electrode show more stability and higher power conversion e?ciencies (PCE) (13.83%, 27% higher than that (10.87%) of the PSCs based on carbon electrodes) due to the higher conductivity and seamless interfacial contact of the MXene electrode. Our work proposes a promising future application for MXene and also a good electrode candidate for HTM and the noble-metal-free PSCs.
关键词： noble-metal-free electrodes,hole transporting materials,perovskite solar cells,2D MXenes,Ti3C2
更新于2025-09-12 10:27:22