Surface Plasmon Resonance Effect Research Articles

Plasmonic photothermal driven MXene-based gas sensor for highly sensitive NO2 detection at room temperature

Gas-sensing devices built on two-dimensional layered transition metal carbide/nitride (MXene) have gathered burgeoning interest in the exploration of next-generation artificial olfaction system, yet it still suffers from weak sensitivity and sluggish or incomplete response/recovery characteristics especially when operating at room temperature, which can drastically restrict its large-scale application in the field of Internet of Things. Herein, the sensitization strategy based on the plasmonic photothermal effect is proposed to exploit a light-assisted MXene-based gas sensor for achieving the highly sensitive detection of NO2 at room temperature. In-situ grown Ti3C2Tx/TiO2/Au heterostructures are employed as the sensitive element for the adsorption and reaction with target gas molecules. Most remarkably, under the activation of 530 nm light, the plasmonic photothermal driven Ti3C2Tx/TiO2/Au sensor exhibits prominent response capability for 1 ppm NO2 which is 7.6 and 2.34 folds larger than that of Ti3C2Tx/TiO2 and Ti3C2Tx/TiO2/Au sensor without light illumination, respectively. The as-designed gas sensor also manifests fast response/recovery times (5.4/15.3 s), superior sensitivity, and excellent selectivity. The association of theoretical and experimental investigations confirms that the enhanced gas-sensitive properties are principally ascribed to the elevation of photon utilization induced by the localized surface plasmon resonance (LSPR) effect and the multiplication of the gas-sensitive reaction pathway derived from the localized photothermal effect. These results illustrate that photothermal-activated enhancement can be used as an effective and general strategy to offer a promising perspective for developing high-performance room-temperature-operated gas-sensing devices.

Photothermal oxidative dehydrogenation of propane to propylene over Cu/BN catalysts.

Oxidative dehydrogenation of propane (ODHP) is a reaction with significant practical significance. As for the industrial application of ODHP, it is challenging to achieve high activity and high propylene selectivity simultaneously. In this study, to overcome this obstacle, we designed a series of Cu/BN catalysts with unique morphologies for establishing a photothermal ODHP system with high efficiency and selectivity. Characterization and evaluation results revealed that Cu/BN-NS and Cu/BN-NF with enlarged specific surface areas exhibited higher catalytic activities. The localized surface plasmon resonance (LSPR) effect of Cu nanoparticles further enhanced the photothermal catalytic performances of Cu/BN catalysts under visible light irradiation. To the best of our knowledge, it is the first time to establish a BN-based photothermal ODHP catalytic system. This study is expected to pave pathways to realize high activity and propylene selectivity for the practical application of ODHP.

Near-infrared activated liposomes for neuroprotection in glaucoma.

Neurodegenerative diseases have a profound impact on vision, leading to conditions such as glaucoma, optic neuropathy, and diabetic retinopathy, affecting millions worldwide. These diseases are characterized by the degeneration of retinal ganglion cells (RGCs), resulting in a progressive loss of visual acuity and field, with the threat of irreversible blindness. However, existing treatments, such as eye drops, direct injections, and laser surgeries face significant challenges due to limited efficacy and potential infection. The inefficiency of traditional corneal drug delivery methods is a major obstacle in treating vision neurodegenerative diseases. To address these challenges, we developed a remotely triggered on-demand liposomal delivery system to treat glaucomatous neurodegeneration in mice. We utilized the localized surface plasmon resonance (LSPR) effect of gold nanorods (AuNRs) under near-infrared (NIR) light (808 nm) to control the release of cyclodextrin-encapsulated melatonin from thermally responsive liposomal nanocarriers in the vitreous humor. Due to the transparency of the eye's cornea, NIR light can penetrate deep tissues, enabling on-demand drug delivery to the retina. By enhancing the drug's solubility and stability through cyclodextrin encapsulation, this remotely activated melatonin/HPβCD AuNRs liposomes delivery system can decrease intraocular pressure (IOP) elevation by (24 ± 7)%, enhance the survival rate of RGCs by (77 ± 6)%, and decrease glial fibrillary acidic protein (GFAP) activation by (75 ± 6)% at depth in an acute experimental glaucoma model. This NIR-triggered drug delivery system presents the potential of a promising minimally photo-triggered therapeutic option for glaucoma treatment.

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.

Robust Bi-anchoring carbon dot/BiOCl sheet heterojunction photocatalysts toward superior photocatalytic activity.

BiOCl has attracted much attention due to its robust layered structure, excellent photocatalytic activity and nontoxicity. However, its practical application is hindered by its narrowband UV photoresponse and rapid recombination of photocarriers. Herein, zero-dimensional Bi-anchoring carbon quantum dot (Bi-CD)/two-dimensional BiOCl heterojunction (Bi-CD/BiOCl) photocatalysts are designed and synthesized by a facile hydrothermal method. Under 190-1100 nm broadband light irradiation, the optimized Bi-CD/BiOCl sample exhibits a superb rhodamine B (RhB) degradation rate of nearly 100%, which is 2.3 (1.7) times that of pristine BiOCl (CD/BiOCl). Additionally, the optimized sample exhibits an RhB degradation rate of up to 88.1% even under direct outdoor light and robust durability in water solution. Experimental results combined with DFT calculations reveal that the superior photocatalytic activity arises from the synergetic effects of broader light absorption due to the incorporation of CD, extra hot electron excitation by the localized surface plasmon resonance (LSPR) effect of metallic Bi, and enhanced electron transfer across the heterojunction interface as well as the existence of more oxygen vacancy traps in BiOCl. This work gives insights into the structure and photocatalytic properties of Bi-CD/BiOCl and provides a new strategy for the design and fabrication of robust high-performance photocatalysts under wide spectrum light irradiation.

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.

Chemodynamic PtMn Nanocubes for Effective Photothermal ROS Storm a Key Anti-Tumor Therapy in-vivo.

Chemodynamic therapy (CDT) is a new treatment approach that is triggered by endogenous stimuli in specific intracellular conditions for generating hydroxyl radicals. However, the efficiency of CDT is severely limited by Fenton reaction agents and harsh reaction conditions. Bimetallic PtMn nanocubes were rationally designed and simply synthesized through a one-step high-temperature pyrolysis process by controlling both the nucleation process and the subsequent crystal growth stage. The polyethylene glycol was modified to enhance biocompatibility. Benefiting from the alloying of Pt nanocubes with Mn doping, the structure of the electron cloud has changed, resulting in different degrees of the shift in electron binding energy, resulting in the increasing of Fenton reaction activity. The PtMn nanocubes could catalyze endogenous hydrogen peroxide to toxic hydroxyl radicals in mild acid. Meanwhile, the intrinsic glutathione (GSH) depletion activity of PtMn nanocubes consumed GSH with the assistance of Mn3+/Mn2+. Upon 808 nm laser irradiation, mild temperature due to the surface plasmon resonance effect of Pt metal can also enhance the Fenton reaction. PtMn nanocubes can not only destroy the antioxidant system via efficient reactive oxygen species generation and continuous GSH consumption but also propose the photothermal effect of noble metal for enhanced Fenton reaction activity.

Enhancement of NaYF<sub>4</sub>:Yb<sup>3+</sup>/Er<sup>3+</sup> up-conversion luminescence based on anodized alumina template

Up-conversion nanoparticle (UCNP) can collect near-infrared (NIR) light and convert it into visible light. Therefore, UCNP has potential applications in fields such as biomedicine, anti-counterfeiting, and solar cells. However, the efficiency of traditional UCNP in the above-mentioned fields is relatively low, greatly limiting its use in related fields. Therefore, enhancing the up-conversion luminescence intensity of up-conversion nanoparticles is particularly important and urgently needed. In this work, anodic alumina templates are used to enhance the luminescence intensity of up-conversion nanocrystals. NaYF<sub>4</sub>:Yb<sup>3+</sup>, Er<sup>3+</sup>with a diameter of 35 nm is prepared by using co-precipitation method. Single pass AAO templates with pore size and pore spacing of 88 nm and 100 nm are prepared by using two-step anodization method. Finally, NaYF<sub>4</sub>:Yb<sup>3+</sup>, Er<sup>3+</sup>/AAO composite structures are formed by using spin coating method. The red green light emission intensity of NaYF<sub>4</sub>:Yb<sup>3+</sup>, Er<sup>3+</sup>/AAO sample can increase 4.4 and 9.0 times that of NaYF<sub>4</sub>:Yb<sup>3+</sup>, Er<sup>3+</sup>/Al reference sample, respectively. The enhancement mechanism is explored by using the finite difference time domain method, and the results show that the primary source of enhancement is the localized surface plasmon resonance effect of the pores in the anodic alumina template. At the same time, the relationship between the up-conversion luminescence intensity of NaYF<sub>4</sub>:Yb<sup>3+</sup>, Er<sup>3+</sup>/AAO sample and the incident angle is investigated. The experimental results show that as the incident angle increases, the luminescence intensity of the red and green light of NaYF<sub>4</sub>:Yb<sup>3+</sup>, Er<sup>3+</sup>/AAO samples first decrease and then increase. Due to the coupling of the local surface plasmon resonance with the excitation wavelength and emission wavelength, the up-conversion luminescence intensity of the sample can be affected. The relationship of AAO channel enhancement factor with incident angle at excitation wavelength and emission wavelength is studied by using the finite difference time domain method. The results indicate that as the incident angle increases, the enhancement factor at the excitation wavelength decreases, while the enhancement factor at the emission wavelength increases after being illuminated at an incident angle of 15°. Therefore, when the incident angle is less than 20°, the electric field intensity at 980 nm dominates, but when it is greater than 20°, the electric field intensity at 540 nm and 650 nm takes precedence. The above results provide a reference for putting them into practical applications in the fields of anti-counterfeiting and solar cells.

Light Absorption Performance of Graphene Photodetector Based on Localized Surface Plasmon Resonance Effect

Light Absorption Performance of Graphene Photodetector Based on Localized Surface Plasmon Resonance Effect

Localized surface plasmon resonance effect of 3-mercaptopropionic acid capped on silver nanoparticles for sensing probe application

Metal nanoparticles such as gold and silver are often used in various nanotechnology applications due to the localized plasmon resonance effect that occurs when incident photons interact with metal nanoparticles. 3-mercaptopropionic acid (3-MPA) is one of the capping molecules that can be provided for surface functionalization on gold or silver core because it has thiol and carboxylic group as a linking biomolecule, and this allows the use of nanoparticles for biosensor applications. In this study, we successfully synthesized silver nanoparticles capped by 3-mercaptopropionic acid (AgMPA) by use of two kinds of methods i.e ligand exchange and direct reduction, which reveal the unique characteristic plasmonic peaks of AgNP around 430 nm and 436 nm, respectively with spherical shape of AgNP and diameter size about 6-20 nm. The transmittance spectra from Fourier Transform Infrared (FTIR) measurement shows that S-H coordination from 3-MPA is invisible after 3-MPA attach on Ag core due to the strong coordination between Ag and the sulfur (S) ion, while the broaden peaks at 1589 and 1385 cm-1 for AgMPA are assigned to asymmetric and symmetric vibrations of carboxylate groups which overlap between carboxylate from citrate and 3-MPA. Finally, the colorimetric detection using AgCA and AgMPA as sensing probe was carried out by use of Biocytin-Avidin system molecule as analyte, which resulted in the colour changed rapidly from yellow to transparent-yellow and the red-shifted of absorbance spectra indicating the attachment of analyte to functionalized molecule of our synthesized AgCA and AgMPA.

Addition of silver nanoparticles to the zinc ferrite/polyaniline composition for boosting its visible photocatalytic degradation.

Enhancing the photocatalytic activity of ZnFe2O4 with a good energy band gap to degrade industrial waste under sunlight illumination can help to develop green environments. Here, to improve the photocatalytic efficiency of ZnFe2O4 ferrites, they were merged with polyaniline (PAni) and silver (Ag) nanoparticles to synthesize Ag@ZnFe2O4-PAni plasmonic nanostructures. The as-synthesized nanostructures were characterized using a series of advanced characterization techniques to confirm successful formation and investigate photocatalytic improvement origins. It was found that incorporating Ag NPs along with the PAni to ZnFe2O4 increases its absorption power and red-shifts its energy band gap, which increases the electron-hole production rate by exposure to light in ZnFe2O4. Contribution of the surface plasmon resonance effect of Ag NPs and conjugated double bonds of PAni to charge transfer mechanisms in Ag@ZnFe2O4-PAni material increased charge separation during photocatalytic process, boosting the photodegradation performance of ZnFe2O4.

Plasma Ag nanoparticles loaded on Bi2MoO6 to enhance surface oxygen vacancies for efficient nitrogen conversion to ammonia

Ag metal-loaded Bi2MoO6 exhibited much higher photocatalytic nitrogen fixation activity than that of pure Bi2MoO6 due to the surface plasmon resonance effect of its Ag NPs and enhanced oxygen vacancy concentration.

A Novel Plasmonic Sensor Based on Dual-Channel D-Shaped Photonic Crystal Fiber for Enhanced Sensitivity in Simultaneous Detection of Different Analytes.

A dual-channel D-shaped photonic crystal fiber (PCF) based plasmonic sensor is proposed in this paper for the simultaneous detection of two different analytes using the surface plasmon resonance (SPR) technique. The sensor employs a 50 nm-thick layer of chemically stable gold on both cleaved surfaces of the PCF to induce the SPR effect. This configuration offers superior sensitivity and rapid response, making it highly effective for sensing applications. Numerical investigations are conducted using the finite element method (FEM). After optimizing the structural parameters, the sensor exhibits a maximum wavelength sensitivity of 10000 nm/RIU and an amplitude sensitivity of -216 RIU -1 between the two channels. Additionally, each channel of the sensor exhibits its unique maximal wavelength and amplitude sensitivities for different refractive index (RI) ranges. Both channels demonstrate a maximal wavelength sensitivity of 6000 nm/RIU. In the RI range of 1.31-1.41, Channel 1 (Ch1) and Channel 2 (Ch2) achieved their maximum amplitude sensitivities of -85.39RIU -1 and -304.52 RIU -1 , respectively, with a resolution of 5×10 -5 . This sensor structure is noteworthy for its ability to measure both amplitude and wavelength sensitivity, providing enhanced performance characteristics suitable for various sensing purposes in chemical, biomedical, and industrial fields.

Mangosteen pericarp extract mediated synthesis of Ag/TiO2 nanocomposite and its application on organic pollutant degradation by adsorption-photocatalytic activity

Herein, Ag/TiO2 nanocomposite was synthesized via a green chemistry approach, which is an eco-friendly, simple, and cost-effective method involving mangosteen pericarp extract as a reducing agent. The as-prepared nanocomposites were characterized using X-ray powder diffraction (XRD), Fourier transformation infrared spectroscopy (FT-IR), UV-Vis spectrophotometer, Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDS), Transmission electron microscopy (TEM), Zeta potential measurement, and nitrogen (N2) adsorption-desorption analysis. The performance of Ag/TiO2 nanocomposite was examined by degradation of methylene blue (MB) dye as a model of organic pollutant. The dye degradation using the Ag/TiO2 nanocomposite containing 45 mM of Ag revealed the high MB degradation, which is 85.77 % after 30 min under dark condition. Furthermore, complete degradation of 96.76 % was achieved after 2 h under visible light irradiation. In contrast, bare TiO2 only achieved 41.45 % after 30 min dark and 2 h visible light irradiation. This increase in degradation efficiency can be attributed to the adsorption process and the enhanced light absorption resulting from the localized surface plasmon resonance (LSPR) effect of Ag. Therefore, the green-synthesized Ag/TiO2 nanocomposite has great potential as an integrated adsorbent photocatalyst materials for remediating organic pollutants in dye effluents.

Investigation of the effect of plasmonic Au nanoparticles on crystalline Si solar cells

In order to increase the photocurrent of tandem solar cells with a silicon (Si) solar cell as the bottom cell, we investigate the relationship between the localized surface plasmon resonance effect of gold nanoparticles (AuNPs) and the arrangement of AuNPs onto solar cells. AuNPs were deposited on P-type crystalline Si (c-Si) cells and Si heterojunction (SHJ) type cells. To obtain the localized surface plasmon resonance effect, the shape, size, and arrangement of the nanostructures are important. Especially, arrangement of AuNPs onto solar cells was inquired in this study because these parameters must be adjusted appropriately to produce a plasmon resonance in a specific wavelength range. It was found that the plasmon resonance effect is significant when deposited on the surface of c-Si cell rather than on top of the Ag electrode. AuNPs deposition on the c-Si cell surface leads to not only the localized surface plasmon resonance effect but also improvement in charge transport between the c-Si cell surface and Ag electrode. However, in the SHJ-type cells, the plasmon resonance effect was not observed because the surface layer was composed of a W-doped In2O3 (IWO) layer.

Surface plasmon resonance effect of silver decorated on BiOCl and its enhanced sunlight-active photodegradation of rhodamine B (RhB) dye and ofloxacin (OFL) antibiotic

Fast electron-hole recombination rate is the major problem concerning low photocatalytic performance of the UV-active BiOCl photocatalyst. To overcome this drawback, decoration of noble metals on the surface of semiconducting photocatalysts can be regarded as one of the promising strategies to improve the photoactivity due to a synergy of heterojunction formation and surface plasmon resonance effect. However, the huge dosage (larger than 10 wt%) of the noble metal incorporated on photocatalyst surface causes high cost in production of the final product. In this work, solvothermally grown BiOCl photocatalyst was decorated with low silver metal loading of 2.5–10 wt%. The tetragonal 2.5 wt%Ag/BiOCl photocatalyst exhibited complete photodegradation of Rhodamin B (RhB) dye and ofloxacin (OFL) antibiotic under natural solar light. The enhancement of the resultant photocatalytic efficiency is possibly due to increasing of charge carrier separation efficiency at the interface together with the formation of the Schottky barrier at the Ag/BiOCl interface so that an improvement in quantum efficiency and an increase in the photocatalytic activity are expected. In addition, well dispersion of silver on BiOCl also leads to red shift in the absorption of light toward visible regime. This is due to the local surface plasmon resonance (LSPR) effect of Ag on BiOCl surface. The synthesized Ag/BiOCl photocatalyst displays enhanced photocatalytic activity with great structural stability after five times of use indicating its excellent cycling ability. The present finding offers a new pathway to create a silver decorated BiOCl for complete removal of harmful dye and antibiotic in aqueous solution. The treatment of toxic organic pollutants in the natural water can be done very easily by utilization of the green technology based on photocatalytic method with the beneficial of abundant solar energy.

Photodeposition synthesis of hollow g-C3N4/Ag nanotubes with high oxidation properties to enhance visible-light photocatalytic performance

A hollow Ag-deposited g-C3N4 nanotube (CNNT/Ag) with high oxidation properties was synthesized using a simple photodeposition method. The g-C3N4 nanotubes provided abundant active sites and a large specific surface area for effective deposition of Ag nanoparticles. The Ag NPs expanded the light absorption range of g-C3N4 through surface plasmon resonance (SPR) effects and acted as an electron acceptor, effectively inhibiting the recombination of photogenerated carriers, thereby improving the charge separation efficiency. The CNNT/Ag composites exhibited excellent photocatalytic performance in the visible light degradation of rhodamine B and tetracycline, 6.42 and 2.16 times higher than pure g-C3N4, respectively. The increased photocatalytic activity of CNNT/Ag composites was attributed to the synergistic electron transfer interface between CNNT and Ag NPs, promoting the migration efficiency of photo-generated carriers. This work presented a promising strategy for constructing effective photocatalysts for degrading organic pollutants using morphology optimization and SPR effects on noble metal surfaces.

Boosting infrared absorption through surface plasmon resonance enhanced HgCdTe microcavity

As one of the most widely used infrared (IR) detectors, a mercury cadmium telluride (MCT) detector usually requires liquid nitrogen refrigeration to suppress thermally activated noise mechanisms that are inherent to its narrow bandgap, which limits its practical applications. Therefore, it is essential to develop strategies to suppress dark current with reduced cooling demand. In this work, a surface plasmon resonance (SPR) enhanced MCT microcavity was proposed to intensify optical absorption across a broadband while diminishing the thickness of the MCT layer to reduce intrinsic dark current proportional to the volume of the absorber. The microcavity is formed by sandwiching the MCT layer between a top well-designed hybrid golden-cross antenna array and a bottom golden reflector. The microcavity is employed to trap the incident light to amplify the absorption, and the golden-cross antenna array is introduced to not only significantly enhance the incident light field through the SPR effect but also to broaden the microcavity resonant mode. Numerical calculation indicated that an absorptance exceeding 95.3% can be attained at 3.4 μm with the full width at half maxima (FWHM) extending beyond 1.38 μm, which almost covers the absorption band of MCT in mid-wavelength IR (MWIR), all while the MCT layer is only 530 nm. Moreover, the prototype device unit was fabricated and tested. Measured peak absorption reached 98.7% @ 3.6 μm and FWHM was as broad as 1.12 μm. These results demonstrate that the high and wideband absorption in an ultrathin MCT layer is achieved based on the synergistic effects of SPR and microcavity resonance.

Hydrothermal carbonization carbon induced synthesis of flower-like C/Bi/BiOI heterojunction with heightened photocatalytic Cr(VI) reduction

Modification with metallic Bi and formation heterojunction with carbon material are considered as the compelling strategies to address the shortcoming of bismuth oxyhalide in photocatalytic Cr(VI) reduction. However, the simultaneous and in-situ synthesis of metallic Bi and hydrothermal carbonization carbon (HC) on BiOI to fabricate a ternary heterojunction photocatalyst remains a challenge yet, and the synergistic mechanism between the localized surface plasmon resonance (LSPR) effect and HC is still indistinct. Herein, a ternary heterojunction photocatalyst comprising metallic Bi, HC, and flower-like BiOI was designed and synthesized through the in-situ induction of HC. During the solvothermal synthesis, a portion of Bi3+ was reduced to metallic Bi nanoparticles, and simultaneously gauzy HC was formed. In the ternary heterojunction, the metallic Bi nanoparticles displayed strong LSPR effect, and the coated HC was conducive to transferring photogenerated electrons and enriching Cr(VI). Due to the synergistic effect of metallic Bi and HC, multiple channels for photogenerated carrier transfer were constructed. Deriving from the excellent light-harvesting, accelerated transfer/separation, and restrained recombination of photogenerated carriers, the ternary heterojunction of flower-like C/Bi/BiOI showed superior photocatalytic Cr(VI) reduction. The reaction rate constant of photocatalytic Cr(VI) reduction was about 26 times higher than that of BiOI.

AuNPs/GO Coated U-Shape Polished SMF Based Localized SPR Sensor for Musta’mal Water Identification

Potential of hybrid gold nanoparticles/graphene oxide (AuNPs/GO) coated single mode fiber (SMF) sensor by exploiting localized surface plasmon resonance (LSPR) effect for Musta’mal water identification was studied. Three structure shapes of fiber optics such as straight-shape, loop-shape and u-shape had been prepared. Three layers of AuNPs with 50 nm in diameter were drop-casted onto the partially unclad polished single mode fiber (SMF) to observe the maximum sensitivity of LSPR. To enhance the LSPR effect, one layer of GO was deposited on top of the AuNPs layer. Two optical light sources with least attenuation (1310 nm and 1550 nm) were employed to study the optical power output as the sensor immersed in different type of water samples. The u-shape SMF portrayed the maximum output power about 24.2 dBm at 1550 nm wavelength. According to the analysis, the deployment of 1550 nm laser wavelength resulted in better sensitivity with 23.2% improvement compared to 1310 nm wavelength. Apparently, the LSPR phenomenon created by AuNPs/GO able to enhance the plasmonic signal up to 51.9% than the uncoated SMF. The thinnest diameter of SMF’s cladding, d=0.1195 mm with U-shape structure exhibited the highest power different of 1.10 dBm, in which suggested the best sensing performance. In conclusion, the optimization of AuNPs/GO u-shape polished SMF resulted in the maximum sensitivity with value of S=72.7 dBm/RIU for Musta'mal water identification.