Surface Plasmon Resonance Effect Research Articles

Nanoparticles as Catalysts: Exploring Potential Applications

Abstract: Nanoparticles have emerged as highly promising catalysts due to their unique physical and chemical properties arising from their small size and high surface area–to–volume ratio. This review delves into the diverse applications of nanoparticles as catalysts in various chemical reactions. A key advantage lies in their substantial surface area–to–volume ratio, facilitation, enhanced accessibility of reactants, and heightened interaction with the catalyst surface. This distinctive characteristic results in improved catalytic activity and efficiency. Additionally, size-dependent properties, such as surface plasmon resonance and quantum confinement effects, offer opportunities for tailoring catalytic behavior. Despite their immense potential, challenges such as synthesis, stability, toxicity, aggregation, and recyclability require attention. Future research should prioritize scalable and sustainable synthesis methods, improve catalyst stability under harsh conditions, and ensure safe handling and disposal. This review provides an overview of the role of nanoparticles as catalysts and highlights their significance in various fields, highlighting their exceptional performance, versatility, and environmental benefits.

Effect of hot electron induced charge transfer generated by surface plasmon resonance on Ag@Au/ITO/PNTP systems

The present study discusses the fabrication of a bimetallic material consisting of silver nanorods and gold nanospheres (designated Ag@Au), and its surface modification with 4-nitrothiophenol (PNTP) after deposition on an indium tin oxide (ITO) glass sheet, followed by laser irradiation at various wavelengths. The results indicate that the reduction of PNTP is more complete under irradiation at 532 nm due to the surface plasmon resonance (SPR) effects of the gold and silver nanomaterials. Moreover, the surface enhanced Raman scattering (SERS) of the PNTP adsorbed on the Ag@Au/ITO is found to be significantly stronger than that of PNTP adsorbed on Ag@Au alone, due to charge transfer (CT) at the interface. In addition, the SERS enhancement effect of the PNTP molecules on the Ag@Au/ITO substrate is optimal under 532 nm laser irradiation due to the hot electron-induced CT generated by the SPR effect. Thus, the system constructed herein combines the effects of SPR and CT, thereby assisting in a further understanding of the enhancement mechanism of SERS and, hence, the further development SERS research in metal-semiconductor-molecular systems.

Preparation of core-shell structure Ag@TiO2 plasma photocatalysts and reduction of Cr(VI): Size dependent and LSPR effect

The poor light absorption and low carrier separation efficiency of Titanium dioxide (TiO2) limit its further application. The introduction of plasma metal Ag have the potential to solve these drawbacks owing to its plasma resonance effect. Thus core-shell structure Ag@TiO2 plasma photocatalysts was prepared by using facile reduction method in this work. More specifically, Ag@TiO2 composite catalysts with different Ag loading amounts were prepared in the presence of surfactant PVP. Ag@TiO2 demonstrates excellent light absorption performance and photoelectric separation efficiency compared with pure TiO2. As a result, it displays excellent performance of Cr(VI) reduction under visible light. The optimal composite catalysts Ag@TiO2–5P achieves exceptional visible-light-driven photocatalytic Cr(VI) reduction efficiency of 0.01416 min−1 that is 2.29 times greater than pure TiO2. To investigate the role of PVP, we also synthesized Ag@TiO2-5 without PVP. The experimental results show that although Ag@TiO2-5 Cr(VI) reduction performance is superior to pure TiO2, it significantly decreases compared with Ag@TiO2–5P. The results of TEM and optoelectronic testing show that agglomeration of Ag particles leads to a decrease in the photoelectric separation efficiency of Ag@TiO2-5. The smaller Ag particles provide more active sites and demonstrating a stronger overall local surface plasmon resonance (LSPR) effect. DMPO spin-trapping ESR spectra testing indicates that ∙O2− and ∙OH are the main reactive species. This research provides a potential strategy to prepare Ag-based plasma photocatalysts for environment protection.

Localized surface plasmon resonance-induced bidirectional electron transfer of formic acid adsorption for boosting photocatalytic hydrogen production on Ni/TiO2

Photocatalytichydrogenproduction from formic acid (FA) is a daunting challenge, yet an essential taskforthedevelopmentofhydrogenenergy. In this study, a p-NiO/n-TiO2 heterojunction incorporating 7-nm metallic Ni was fabricated, which demonstrated a remarkable localized surface plasmon resonance (LSPR) effect. Notably, 5 wt% Ni/TiO2 exhibited 1271-fold higher photocatalytic activity (2416 μmol⋅g−1⋅h−1) than TiO2 alone under light radiation at room temperature. The experimental investigations revealed the excitation of distinct components via irradiation by different light sources. Visible light-driven hydrogen production was predominantly influenced by the LSPR-induced hot electrons and holes effects of Ni. Further, FA molecules simultaneously lost and accepted electrons at the Ni0–Ti3+ and Ni0–O2− sites, respectively, generating a bidirectional electron transfer behavior with “valley-shaped” gas-sensitive responses, which was crucial toboosttheactivity. Moreover, the photocatalytic activity was mainly attributed to the heterojunction and defects structure under UV light irradiation, and Ti3+, VOs, and O2− as adsorption sites for FA. Thus, the synergistic interplay among different light sources could effectively boost the photocatalytic hydrogen production performance. Significantly, this research reveals that the LSPR effect of metallic Ni can effectively regulate electron transfer behavior and enhance visible light-driven photocatalytic activity.

Surface plasmon resonance effects of Ag@ZnO core–shell nanostructure in UV and visible light for photodiode applications

AbstractHerein, Ag@ZnO core–shell nanostructures were prepared via the wet chemical method and were then dissolved in methanol and drop cast onto a p–Si wafer. Experimental current–voltage measurements of the Ag@ZnO/p–Si heterojunction device were investigated under both visible and UV illumination of 365 and 395 nm. The photocurrent, responsivity, detectivity, and on/off ratio were found to be dependent on the light intensity of visible light and wavelength of UV light. The low photocurrent at low light intensities and its rapid increase at high light intensities was attributed to the recombination of electrons and holes and also to the presence of traps at low light intensities. The responsivity and detectivity of the photodiode reach 1.32 A/W and 5.47 × 1011 Jones, respectively at 365 nm. On the contrary, the high performance under UV light was explained by the surface plasmon resonance between Ag and ZnO.

Rational Design of Near‐infrared II Plasmonic Optofunctional Materials for Diagnostic and Therapeutic Applications

AbstractPlasmonic materials have aroused considerable interest in diagnostic and therapeutic biomedical applications because of their remarkable optical properties and the integration of multiple functionalities. Particularly, near‐infrared II (NIR‐II) plasmonic materials present great advantages for anticancer treatments, including deep tissue penetration, low tissue light scattering and autofluorescence, and high spatial resolution. Thus, NIR‐II plasmonic phototheranostics represents a promising approach for effective anticancer treatments through multi‐modal imaging‐guided therapy. Accordingly, tremendous efforts have recently been devoted to the development of NIR‐II plasmonic materials for highly efficient phototheranostics. In this review, the recent progress of NIR‐II plasmonic materials and their phototheranostic applications are overviewed. First, the localized surface plasmon resonance effect and the related optical properties such as the photothermal effect, photoacoustic effect, and surface‐enhanced Raman scattering (SERS) effect are introduced. Then, the unique features and the structure‐property relationship of various types of NIR‐II plasmonic materials are discussed. Finally, the recent progress of NIR‐II plasmonic material‐based multimodal phototheranostics with an emphasis on the integration of multiple functionalities are reviewed, and subsequently the current challenges and future research perspectives are discussed. This review will provide valuable guidelines for the rational design of NIR‐II plasmonic materials for highly efficient cancer phototheranostics in the future.

Concurrent Mechanisms of Hot Electrons and Interfacial Water Molecule Ordering in Plasmon-Enhanced Nitrogen Fixation.

The participation of high-energy hot electrons generated from the non-radiative decay of localized surface plasmons is an important mechanism for promoting catalytic processes. Herein, another vital mechanism associated with the localized surface plasmon resonance (LSPR) effect, significantly contributing to the nitrogen reduction reaction (NRR), is found. That is to say, the LSPR-induced strong localized electric fields can weaken the intermolecular hydrogen bonds and regulate the arrangement of water molecules at the solid-liquid interface. The AuCu pentacle nanoparticles with excellent light absorption ability and the capability to generate strong localized electric fields are chosen to demonstrate this effect. The in situ Raman spectra and theoretical calculations are employed to verify the mechanism at the molecular scale in a nitrogen fixation process. Meanwhile, due to the promoted electron transfer at the interface by the well-ordered interfacial water, as well as the participation of high-energy hot electrons, the optimal catalyst exhibits excellent performance with an NH3 yield of 52.09 µg h-1 cm-2 and Faradaic efficiency (FE) of 45.82% at ─0.20V versus RHE. The results are significant for understanding the LSPR effect in catalysis and provide a new approach for regulating the reaction process.

Reflective magnetic field and temperature dual-parameter sensor based on no-core fiber probe

A kind of reflection-type magnetic field and temperature dual-parameter sensor based on surface plasmon resonance (SPR) effect was proposed and investigated. The sensing probe was fabricated with a section of no-core fiber, which was evenly divided into two parts. One part was immersed in magnetic fluid (MF) for magnetic field sensing (Channel 1, referred as CH1). The other part was coated with polydimethylsiloxane (PDMS) for temperature sensing (Channel 2, referred as CH2). The issue of magnetic field and temperature cross-sensitivity was resolved ingeniously. In the magnetic field intensity range of 0–55.1 mT, the maximum magnetic field sensitivity of 122.67 pm/mT was obtained. In the temperature range of 30–70 ℃, the maximum temperature sensitivity was 1662.64 pm/◦C. The sensor has the advantages of simple structure, small size, and potentials for applications in narrow space.

Non-noble plasmonic TiN modified BiOBr for the piezo-photocatalytic removal of sulfisoxazole: Simultaneous improvement of photocatalytic and piezoelectric properties

Piezo-photocatalytic systems have the capacity to degrade environmental contaminants by exploiting mechanical and photonic energy. Herein, we report on a strategy for the modification of bismuth bromide oxide (BiOBr) with a non-noble metal plasma (titanium nitride (TiN)). The synthesized piezo-photocatalytic system demonstrated excellent performance for the degradation of sulfisoxazole (SIZ), where the 2-TiN/BiOBr samples exhibited a high degradation rate of 94.9 % in 70 min, with a rate constant that was 4.68 times higher than that of BiOBr. This improved catalytic performance was attributed to the localized surface plasmon resonance (LSPR) effect and high electronic conductivity of TiN, which improved the photocatalytic and piezoelectric properties of BiOBr. The hypothesis of an extended piezoelectric field was verified in conjunction with density functional theory (DFT) calculations. This work presents a new perspective for improved piezoelectric photocatalytic systems, which have great potential for utilizing solar and mechanical energy for environmental remediation.

High-performance Au@CsPbBrI2 glass for wide color gamut backlit display

Perovskite quantum dots materials have achieved significant progress in the field of optoelectronics owing to their unique advantages, such as a wide color gamut, adjustable wavelength, and low cost. These advantages make them an ideal substitute for CdSe quantum dots in backlit display devices. As a kind of nanoparticles with a localized surface plasmon resonance effect, Au can be effectively used to enhance the photoluminescence of perovskite nanocrystals (NCs). In this study, Au nanoparticles were introduced into a borosilicate glass system with CsPbBrI2 NCs to improve the optical properties. A series of Au@CsPbBrI2 NCs glasses with tunable wavelengths in the range of 628–640 nm was successfully prepared. The photoluminescence quantum yield (PLQY) of the CsPbBrI2 NCs glass was increased from 15% to 68% with the addition of AuBr3. The Au@CsPbBrI2 NC glass showed good aqueous, thermal, and blue light stabilities. Additionally, a backlight conversion film prepared by compounding the Au@CsPbBrI2 NC glass powder exhibiting the optimal properties with polymethylmethacrylate (PMMA), was applied to a liquid crystal display (LCD). The presented image were more saturated and richer. Our results show that the optimized sample has immense potential for practical applications in the field of backlit displays.

Boosted near-infrared shielding properties of cesium-tungsten bronze based on solid state reaction with optimized precursor

Cesium doped tungsten bronze (CWO) nanoparticles can selectively keep high transmittance in the visible while presenting significant shielding rate in the near-infrared region. How to further improve the optical properties of CWO based on solid state method is crucial to the industry production. Based on changing the particle size and morphology of WO3 precursors, cesium-tungsten bronze powders with different dispersivity and concentrations of Cs+ doping were successfully prepared by solid-phase method. The characterization analysis reveals that the precursors with appropriated surface area and morphology are significant to improve the dispersivity of CWO nanocrystal and increase the density of free carriers, thereby improving the small polariton absorption performance and the local surface plasmon resonance effect. The result provides an effective strategy to boost the optical property of CWO nanocrystal synthesized by optimizing the morphology and size of precursor, which is important to the industry production and practical applications in the field of energy-saving window films.

Synergistic enhancement of ultrahigh SERS activity via Cu2O@Ag Core-Shell structure for accurate label-free identification of breast tumor subtypes

Conventional methodology for accurate identification of breast tumor subtypes is complex and time-consuming. Label-free SERS (surface-enhanced Raman scattering) enables rapid detection of biomolecules and provides intrinsic fingerprint information of analytes. Exploring reliable SERS bioprobes with high sensitivity and repeatability is essential for efficient typing of cancer cells. In this study, a novel core-shell noble metal-semiconductor Cu2O@Ag heterostructure with uniform morphology and outstanding SERS activity for label-free detection has been proposed. The Cu2O@Ag SERS substrates exhibit exceptional sensitivity to detect 4 nitrophenthiol (4NTP) at extreme low concentration (10−15 M), and the SERS spectra demonstrate excellent selectivity and repeatability (RSD ≈ 8.84%). The enhancement mechanism is attributed to the synergistic enhancement of photoinduced charge transfer and boosted surface plasmon resonance effect, confirmed by reduced fluorescence lifetime of methylene blue on SERS substrates and enhanced electromagnetic field intensity via finite-difference time-domain computational simulation. The ultrahigh sensitivity and good signal stability endow Cu2O@Ag SERS bioprobe potential for accurate detection of four breast cancer cells subtypes. The rich fingerprint information from SERS spectra is processed using linear differentiation analysis, revealing a high accuracy of 93.3% for subtypes classification. These results demonstrate an excellent SERS bioprobe with high sensitivity and repeatability for precision diagnosis has been developed.

Manipulation of random laser by the bandgap in three-dimensional SiO2 photonic crystals

Photonic crystals (PCs) are artificial structures with different dielectric constants that are arranged periodically in space and can control the propagation of electromagnetic waves of specific frequencies. The photonic bandgap can tune the photon state density, which is beneficial for the generation of random lasers (RLs). In this paper, a thin film of PMMA-doped DCJTB is spun-coated on a silicon dioxide (SiO2)PC to produce an RL. The PC is fabricated by a convenient dip-coating method with variable PBGs by changing the diameter of SiO2 nanospheres. By changing the position of the PBG gap, the RL emission peak can be effectively manipulated with an emission wavelength of up to 16 nm. By adding Au nanoparticles, the lasing performance is improved due to the surface plasmon resonance effect and strong photon scattering, where the emission intensity is increased by 191.9 %, and the threshold is decreased by 37.8 %. The imaging results show that the RL has low spatial coherence, which has a good application in speckle-free imaging. This study provides an effective method to produce a low threshold, high-quality RL with convenient manipulation of lasing properties, which opens the door for expanding its application in optoelectronic devices and speckle-free imaging.

Ag-LSPR and molecular additive: A collaborative approach to improve the photovoltaic performance of perovskite solar cells

The development of multi-functional synergetic strategy with defect passivation and optical management is expected to further improve the photovoltaic performance of perovskite solar cells (PSCs). Herein, the small organic molecule of 4-trifluoromethyl pyridine (TFP) and Ag nanoparticle modified by TFP (Ag@TFP) with local surface plasmon resonance (LSPR) effects were introduced into PSCs. After investigating their different intervention ways in PSCs, a novel technique has been proved to own the ability to achieve the best photovoltaic performance of PSCs, i.e. TFP was introduced into the perovskite layer by anti-solvent method, and then a layer of Ag@TFP was deposited on the perovskite layer. The TFP can both coordinate with Pb related defects and form hydrogen bonds with MA+ and FA+ to effectively inhibit ion migration, so that the perovskite films with high crystal quality and improved stability can be obtained. The further deposition of Ag@TFP enhances the light absorption of perovskite via far-field light scattering effects and produces hot electrons for injection, so that the Jsc and Voc can be greatly increased. Meanwhile, an enhanced near-field electromagnetic field of Ag@TFP increases the build-in field of device, and a more matched energy level alignment has been formed, which greatly accelerates the charge transfer from perovskite to HTL. As a result, the highest PCE of 23.86 % has been achieved in the Ag@TFP-TFP based Cs0.069FA0.826MA0.105Pb(I0.955Br0.045)3 PSCs. This work not only provides an effective approach to improve the photovoltaic performance of PSCs, but also open a new gate to design synergetic strategy with multifunction for prompting the development of PSCs.

Nickel nanoparticle-decorated twinned crystal CdxZn1−xS for enhanced photocatalytic hydrogen production

In photocatalysis, maximizing light absorption and utilizing light-stimulated electrons is of paramount importance. In this study, Ni-decorated CdxZn1−xS twinned crystals were synthesized via solvothermal method with Ni loadings ranging from 0.5 to 5 wt%. The Ni nanoparticles introduced the Surface Plasmon Resonance (SPR) effect, broadening photon absorption and extending the photo-response into the visible light range. Notably, 1 wt % Ni-decorated Cd0.5Zn0.5S exhibited remarkable H2 evolution rate of 1497 μmol(h.gcat)−1. This enhancement is attributed to the SPR effect, which enhances light absorption and photogenerated electron generation, as well as efficient electron transfer facilitated by Ni's lower Fermi level. These findings emphasize the crucial role of optimal Ni loading and the SPR effect in enhancing photocatalytic efficiency.

A tungsten-based metamaterial emitter for solar thermophotovoltaic systems.

Solar thermophotovoltaic systems are capable of showing efficient photoelectric conversion and are expected to surpass the Shockley-Queisser limit, owing to the spectrum-selective functionality of metamaterial selective emitters. Generally, metamaterial emitters are manufactured from multifarious materials, which also makes their manufacturing process complicated. Here, we propose a tungsten-only emitter composed of two rectangular bars with different widths and heights arranged in a cruciform structure, featuring a rectangular cavity at the top. Results from the simulations reveal that the emissivity of the metamaterial emitter exceeds 90% at the wavelength of 950-1590 nm and drops below 20% for wavelengths exceeding 2025 nm, which can effectively match GaSb photovoltaic cells. The outstanding emission performance is attributed to the coupling effect of surface plasmon resonance, cavity resonance and guided mode resonance, as evidenced by the analysis of electric and magnetic fields. We also explored the radiation spectrum in the 500-2500 K temperature range and found that it performed best at 1400 K. It is concluded that the emission performance is slightly affected by structural parameters and angles. This study presents a meaningful exploration of efficient solar utilization.

A new copper nanocluster surface molecular imprinted polymethacrylic acid probe for ultratrace trichlorophenol based on in situ-generated nanogold SPR effects.

A new coinage metal nanocluster surface molecularly imprinted polymethacrylic acid nanoprobe (NC@MIP) for the selective determination of 2,4,6-trichlorophenol (TCP) was prepared via microwave synthesis using 2,4,6-trichlorophenol as a template molecule, copper nanoclusters (CuNC) as a nanosubstrate, and methacrylic acid as a polymer monomer. It was found that the copper nanocluster MIP (CuNC@MIP) shows the strongest catalytic performance for the reduction of HAuCl4 by hydrazine hydrate for the on-site generation of gold nanoparticles (AuNPs) with the surface plasmon resonance (SPR) effects of resonance surface-enhanced Raman scattering (SERS) and resonance Rayleigh scattering (RRS) as well as absorption (Abs). When TCP was added, the CuNC@MIP nanoprobe and TCP-formed CuNC@MIP-TCP nanoenzyme with stronger catalytic activity generated more AuNPs, and the trimodal analytical signal was enhanced linearly. Therefore, a new SERS/RRS/Abs trimodal sensing platform for TCP was constructed, which was simple, rapid, sensitive, and selective. For each mode, the linear ranges were 0.0075-0.075, 0.010-0.10, and 0.010-0.10 nmol L-1, and the detection limits were 0.0010, 0.021, and 0.043 nmol L-1, respectively. The relative deviation of TCP in different water quality was 0.47%-2.5% and the recovery rate was 94.6%-108.6%.

BISMUTH OXYCHLORIDE NANOSHEETS MODIFIED WITH Au-Cu NANOPARTICLES FOR EFFICIENT PHOTOREDUCTION OF CO2 TO ETHANE

BiOCl nanosheets modified with AuCu nanoparticles were successfully designed and fabricated for water reduction of CO2. The AuxCuy/BiOCl composites exhibited enhanced visible light absorption ability due to a surface plasmon resonance (SPR) effect. The AuxCuy/BiOCl composites could convert carbon dioxide to ethane (C2H6), while only CO was obtained over pure BiOCl nanosheets. In this study, the rate of C2H6 production (12.2 μmol h-1 g-1) and selectivity of C2H6 (75.7%) were obtained over the Au1Cu1/BiOCl photocatalyst under simulated sunlight illumination. The AuCu nanoparticles played the dual role of electron traps and hot electron donors, facilitating efficient separation and migration of the carriers. The photocatalyst exhibited steady photocatalytic activity over the test duration of 9 h.

An investigation on a WO3/MoO3−x heterojunction photocatalyst for excellent photocatalytic performance and enhanced molecular oxygen activation ability

A novel Z-scheme WO3/MoO3−x heterojunction was synthesized through hydrothermal method. The heterojunction with unique localized surface plasmon resonance (LSPR) effects had excellent photocatalytic performance.

Regulation of band gap and localized surface plasmon resonance by loading Au nanorods on violet phosphene nanosheets for photodynamic/photothermal synergistic anti-infective therapy.

In the face of the serious threat to human health and the economic burden caused by bacterial antibiotic resistance, 2D phosphorus nanomaterials have been widely used as antibacterial agents. Violet phosphorus nanosheets (VPNSs) are an exciting bandgap-adjustable 2D nanomaterial due to their good physicochemical properties, yet the study of VPNS-based antibiotics is still in its infancy. Here, a composite of gold nanorods (AuNRs) loaded onto VPNS platforms (VPNS/AuNR) is constructed to maximize the potential of VPNSs for antimicrobial applications. The loading with AuNRs not only enhances the photothermal performance via a localized surface plasmon resonance (LSPR) effect, but also enhances the light absorption capacity due to the narrowing of the band gap of the VPNSs, thus increasing the ROS generation capacity. The results demonstrate that VPNS/AuNR exhibits outstanding antibacterial properties and good biocompatibility. Attractively, VPNS/AuNR is then extensively tested for treating skin wound infections, suggesting promising in vivo antibacterial and wound-healing features. Our findings may open a novel direction to develop a versatile VPNS-based treatment platform, which can significantly boost the progress of VPNS exploration.