Plasmonic Silver Nanoparticles Research Articles

Enhanced photothermal performance and water purification via silver and gold plasmonic nanoparticles in polyvinyl alcohol: glutaraldehyde/activated carbon hydrogel

Enhanced photothermal performance and water purification via silver and gold plasmonic nanoparticles in polyvinyl alcohol: glutaraldehyde/activated carbon hydrogel

Highly ordered TiO2 Nanotubes decorated with plasmonic silver nanoparticles (TiO2/Ag) for ultra-sensitive SERS detection of textile dye contaminant Rhodamine 6 G

We report a susceptible, ultrafast, molecular fingerprint-specific detection tool of analytes at an extreme trace concentration using surface-enhanced Raman spectroscopy (SERS). Highly ordered TiO2 Nanotubes (NT) modified with plasmonic Ag nanoparticles (Ag) are fabricated by wet chemical strategy. TiO2/Ag nanostructures could benefit the SERS mechanism arising from the effects of both the charge transfer process within TiO2/Ag/analyte and the enhancement in the electromagnetic field by the twining of plasmonic Ag nanoparticles with the construction of semiconductor/plasmonic bi-component system (TiO2/Ag). To achieve a better density of Ag NPs on TiO2 nanotubes, the photoinduction process irradiation time was varied from 10 min to 40 min. The prepared bicomponent SERS system was validated for its structural and morphological properties. SERS optimization studies were analyzed with the probe molecule Rhodamine 6 G (R6G) with an initial concentration of 10−6M. The highest SERS enhancement was notified with TiO2/Ag20 min for R6G sensing. The fabricated optical sensor reproducibility in signal detection was scrutinized with Raman mapping studies and statistically validated by low RSD values of 9.8%. Furthermore, their detectability was gauged with low concentration detection of R6G down to Pico-molar levels (10−12M). Synergistic effects of both CT and EM contributed to SERS enhancement to trace and detected pico-levels of R6G by the fabricated bicomponent semiconductor/ plasmonic heterostructure system (TiO2/Ag 20 min).

Simultaneous SERS Sensing of Cysteine and Homocysteine in Blood Based on the CBT-Cys Click Reaction: Toward Precisive Diagnosis of Schizophrenia.

At present, there is a lack of sufficiently specific laboratory diagnostic indicators for schizophrenia. Serum homocysteine (Hcy) levels have been found to be related to schizophrenia. Cysteine (Cys) is a demethylation product in the metabolism of Hcy, and they always coexist with highly similar structures in vivo. There are few reports on the use of Cys as a diagnostic biomarker for schizophrenia in collaboration with Hcy, mainly because the rapid, economical, accurate, and high-throughput simultaneous detection of Cys and Hcy in serum is highly challenging. Herein, a click reaction-based surface-enhanced Raman spectroscopy (SERS) sensor was developed for simultaneous and selective detection of Cys and Hcy. Through the efficient and specific CBT-Cys click reaction between the probe containing cyan benzothiazole and Cys/Hcy, the tiny methylene difference between the molecular structures of Cys and Hcy was converted into the difference between the ring skeletons of the corresponding products that could be identified by plasmonic silver nanoparticle enhanced molecular fingerprint spectroscopy to realize discriminative detection. Furthermore, the SERS sensor was successfully applied to the detection in related patient serum samples, and it was found that the combined analysis of Cys and Hcy can improve the diagnostic accuracy of schizophrenia compared to a single indicator.

Plasmonic silver and gold nanoparticles: shape- and structure-modulated plasmonic functionality for point-of-caring sensing, bio-imaging and medical therapy.

Silver and gold nanoparticles have found extensive biomedical applications due to their strong localized surface plasmon resonance (LSPR) and intriguing plasmonic properties. This review article focuses on the correlation among particle geometry, plasmon properties and biomedical applications. It discusses how particle shape and size are tailored via controllable synthetic approaches, and how plasmonic properties are tuned by particle shape and size, which are embodied by nanospheres, nanorods, nanocubes, nanocages, nanostars and core-shell composites. This article summarizes the design strategies for the use of silver and gold nanoparticles in plasmon-enhanced fluorescence, surface-enhanced Raman scattering (SERS), electroluminescence, and photoelectrochemistry. It especially discusses how to use plasmonic nanoparticles to construct optical probes including colorimetric, SERS and plasmonic fluorescence probes (labels/reporters). It also demonstrates the employment of Ag and Au nanoparticles in polymer- and paper-based microfluidic devices for point-of-care testing (POCT). In addition, this article highlights how to utilize plasmonic nanoparticles for in vitro and in vivo bio-imaging based on SERS, fluorescence, photoacoustic and dark-field models. Finally, this article shows perspectives in plasmon-enhanced photothermal and photodynamic therapy.

Paper-based colorimetric hyperammonemia sensing by controlled oxidation of plasmonic silver nanoparticles.

High concentrations of ammonia in the human body can occur due to a wide variety of underlying causes such as liver cirrhosis and the symptoms of high ammonia concentrations are diffuse and hard to diagnose. The measurement of blood ammonia levels is an important diagnostic tool but is challenging to perform at the patient's bedside. Here, we present a plasmonic Ag nanoparticle-based ammonia sensor which provides a colorimetric optical readout and does not require specialised equipment. This is achieved using plasmonic Ag/SiO2 nanoparticles with the sensing mechanism that in the presence of OCl- they rapidly degrade reducing their plasmonic extinction and losing their characteristic colour. However, if ammonia is also present in the system, it neutralises the OCl- and thus the silver nanoparticles retain their plasmonic colour as can be measured by the naked eye or using a spectrometer. This sensing was further developed to enable measurements with animal serum as well as a implementing a facile "dip-stick" style paper-based sensor.

Flexible multiscale cavity with omnidirectionality and high stability for in-site SERS detection of nanoplastics on oyster

Nanoplastics are widespread and pose a potential threat to human health. In this work, we designed a flexible multiscale cavity structured (MCS) surface-enhanced Raman scattering (SERS) substrate decorating Ni3S2 nanocavity on a modified polyvinylidene fluoride (PVDF) microcavity. The dense two-dimensional Ni3S2 nanosheets can provide a large surface area for the deposition of plasmonic silver nanoparticles (Ag NPs), increasing the density and strength of the “hotspots”. Additionally, the nanocavity (width ∼500 nm), formed by the nanosheet surroundings, offers not only electromagnetic enhancement of the cavity mode for SERS but also a crucial detection site for nanoplastics attachment. This effectively addresses the challenge of SERS detection due to the scale mismatch between nanoplastics (>50 nm) and conventional “hotspots” (<10 nm). Moreover, the flexible imprinted PVDF microcavity endows the proposed substrate with omnidirectional “hotspots” enhancement, ensuring the signal stability and the feasibility of in-site detection of the actual sample. As a result, we achieved the successful in-site detection of polystyrene (PS) spheres of different sizes on the surface of oysters, with a detection limit of 10-3 mg/mL for 50 nm diameter. The flexible multiscale cavity SERS substrate is expected to show great potential in food safety and environmental monitoring.

Designing of plasmonic 2D/1D heterostructures for ultrasound assisted photocatalytic removal of tetracycline: Experimental results and modeling

The extensive release of Tetracyclines (TCs) has posed severe environmental challenges. Therefore, there is an urgent need to find greener and more sustainable options for effectively degrading TCs. Here, we will design plasmonic 2D/1D heterostructures that exhibit excellent photocatalytic properties for TC removal. In this research, 2D/1D p-n heterojunctions containing TiO2 nanosheets and NiO nanorods were deposited chemically with various amounts of plasmonic silver nanoparticles (Ag(y)/TNs/NiO(x)). PXRD patterns showed pure anatase and cubic phases for TNs and NiO, respectively, and confirmed that NiO nanorods occupied the (101) facet in TNs. The FESEM and TEM micrographs showed the sheet-like structure and nanorods morphologies for TNs and NiO. The DRS, PL, and Raman studies approved that the NiO nanorods and silver nanoparticles improved the photoresponse of TNs to the visible light region. The Mott–Schottky, EIS and photocurrent analyses indicated that the p-n heterojunction decreased the interfacial resistance, improved the separation of charge carriers, and increased the photocurrent of TNs (from 0.12µA to 3.5µA) in Ag(0.5)/TNs/NiO(0.35) by 30 times. The efficiency of the plasmonic heterojunctions was examined for ultrasound assisted photocatalytic removal of tetracycline (TC). The experimental results were validated using two powerful machine learning techniques (ANN and SGB), and a good accordance between the predicted and experimental values was observed. The reusability tests and electrical energy per order analysis revealed that using plasmonic heterojunctions (Ag(y)/TNs/NiO(0.35)) were more cost-effective and sustainable than using the conventional TiO2 photocatalytic system.

Plasmonic silver nanoparticles anchored ethylenediamine-titania nanobelt composite photoanode for efficient electron transport in dye-sensitized solar cell

An efficient photoanode is a decisive requirement for attaining impressive performance in dye-sensitized solar cell (DSSC). Consequently, in the present study, TiO2 nanobelts (TiO2 NBs) are synthesized by solvothermal route and silver nanoparticles (Ag NPs) are anchored on TiO2 NBs surface through ethylenediamine functionalization (NH2-TiO2 NB/Ag). Ethylenediamine plays dual roles of reducing agent and linker molecule between TiO2 and Ag NPs by means of metal-ligand bonding with Ag NPs. The prepared plasmonic NH2-TiO2 NB/Ag nanocomposites (NCs) are characterized by diffuse reflectance spectroscopy, Raman spectroscopy, XRD, HR-TEM and XPS. The NH2-TiO2 NB/Ag NCs have strong light absorption and high dye loading. The DSSC integrated with 2wt% Ag NPs anchored NH2-TiO2 NB/Ag-2 NC photoanode has exhibited improved photovoltaic performance with power conversion efficiency (PCE) of 7.56 %, which was ∼97 % greater over the PCE of DSSC constructed using unmodified TiO2 NBs photoanode (3.84 %).

Discrimination of resected glioma tissues using surface enhanced Raman spectroscopy and Au@ZrO2 plasmonic nanosensor

Gliomas present one of the most prevalent malignant tumors related to the central nervous system. Surgical extraction is still a preferred route for glioma treatment. Nonetheless, neurosurgeons still have a considerable challenge to detect actual margins of the targeted glioma intraoperatively and correctly because of its great natural infiltration. Here we evaluated the possibility of using surface-enhanced Raman spectroscopy to analyze freshly resected brain tissues. The developed method is based on the application of Au@ZrO2 nanosensor. The plasmonic properties of the sensor were first tested on the analysis of Rhodamine 6G, where concentrations down to 10-7 mol/L can be successfully detected. We also compared the performance of the nanosensor with silver plasmonic nanoparticles, where similar results were obtained regarding the reduction of the fluorescence background and enhancement of the intensity of the measured analytical signal. However, application of silver nanospheres led to increased variations in spectral data due to its probable aggregation. Applied ZrO2@Au nanosensor thus dramatically lowers the fluorescence present in the Raman data, and considerably improves the quality of the measured signal. The developed method allows for rapid discrimination between the glioma's periphery and central parts, which could serve as a steppingstone toward highly precise neurosurgery.

Microalgae-enhanced bioremediation of Cr(VI) ions using spent coffee ground-derived magnetic biochar MoS2–Ag composites

Composites of magnetic biochar derived from spent coffee grounds were prepared using MoS2 decorated by plasmonic silver nanoparticles (MoS2–Ag), which were used for the bioremediation Cr6+ ions. The composites were characterized by electron microscopy, X-ray diffraction, Raman, and UV-VIS spectroscopy. The bioremediation of Cr6+ ions was enhanced almost two times compared to microalgae, Spirulina maxima. Such an increased activity is attributed to heterojunction formation of Biochar@MoS2–Ag composite due to the synergetic effects of surface plasmon resonance of AgNPs inducing amplified local electric field, thus simultaneously increasing the absorption of MoS2 under visible or near-infrared light. The combination of Biochar@MoS2–Ag and Spirulina maxima powder was effective for the separation (microalga-based absorption and accumulation of Cr6+ ions) of photo-induced carriers (composite-assisted to breakdown Cr6+ ions). This study offers efficient eco-friendly treatment of Cr6+ ions by reporting the first enhanced bioremediation of Cr(VI) ions by microalgae using MoS2–Ag-modified biochar obtained from consumed coffee grounds.

Femtosecond Laser Fabrication of Silver Microstructures in Nanoporous Glasses

This paper presents the results of studying the process of laser formation of microstructures from silver nanoparticles in nanoporous quartz glasses. Glass samples were impregnated with organometallic molecules Ag(hfac)COD in a supercritical carbon dioxide environment. The formation of point and linear microstructures was carried out by high-frequency (70 MHz) femtosecond laser radiation with a wavelength of 525 nm and energy in the pulse up to 1 nJ. It was found that the formation of microstructures occurs due to photo- and thermal decomposition of precursor molecules with the formation of plasmonic silver nanoparticles. It is shown that the developed temperatures can exceed the melting point of glass, which leads to the appearance of microstructures with altered refractive index. A qualitative model explaining the individual stages of cluster formation in the glass volume under point laser impact is presented.

Formation of plasmonic silver nanoparticles by glucosamine reduction: Application to a colorimetric sensor for determination of glucosamine in its pharmaceutical preparations

The purpose of this study is to develop a novel method for synthesizing silver nanoparticles using glucosamine as reducing agent and to utilize the developed method for colorimetric detection and quantitative determination of the non-chromophoric drug, glucosamine. Silver nanoparticles are prepared by reducing 0.02 mol/L silver nitrate by glucosamine in 0.075 mol/L ammonia and stabilizing the nanoparticles with 0.1% polyvinylpyrrolidone and the mixture is heated at 90 °C for 5 min. The prepared silver nanoparticles dispersed in water exhibit a bright yellow color due to a localized surface plasmon resonance band at 412 nm. The principle of glucosamine sensing is based on measuring the intensity of the surface plasmon resonance band at 412 nm which is directly proportional to the concentration of glucosamine with a linearity range (1 – 9 μg/mL), limit of detection 0.33 μg/mL and limit of quantitation 1.0 μg/mL. The proposed method was validated according to the ICH guidelines, and it was found to be accurate, precise, selective, and robust. The method was applied for determination of glucosamine in Joflex® capsules using the standard addition approach with mean % recovery ± standard deviation of 100.077 ± 1.786. The method is simple, rapid, and cost-effective and can be used for determination of glucosamine in bulk and in its pharmaceutical preparations.

Ternary Heterostructures Based on BaTiO3/MoO3/Ag for Highly Efficient and Reusable Photocatalytic Applications

AbstractThis work shows the fabrication of an efficient ternary heterostructure photocatalyst by integrating ferroelectric BaTiO3 (BTO) as the bottom layer, semiconductor MoO3 as the middle layer and plasmonic silver nanoparticles (Ag NPs) as the top layer, respectively. The BaTiO3/MoO3/Ag (BMA) heterostructure exhibits a higher photodegradation and photocatalytic efficiency of 100% for rhodamine B (RhB) dye under a UV–Visible light illumination of 60 min when compared with its binary heterostructure counterparts BaTiO3/Ag (BA) and MoO3/Ag (MA). The increased photocatalytic activity in BMA heterostructure is attributed to its enhanced interfacial electric field due to the electric double layer formation at BTO‐MoO3 and MoO3‐Ag interfaces. The higher blueshift in the surface plasmon resonance (SPR) peak observed for the BMA heterostructure clearly indicates an increased electron transfer toward the top Ag NPs layer under optical illumination. The higher resistive switching (RS) ratio, the increased difference in voltage minima, and the improved photocurrent generation, as evident from the I–V characteristics, illustrate the enhanced charge carrier generation and separation in BMA heterostructure. A smaller arc radius observed for the Nyquist plot of BMA heterostructure clearly showcases its increased interfacial charge transfer (CT). The CT mechanism and reusability of the BMA heterostructure are also studied.

Plasmonic nanoparticles doped metal oxide hybrid materials for efficient photocatalytic dye degradation and strong anti-biofilm activity

Plasmonic silver nanoparticles (AgNPs) doped ZnO (Ag-ZnO) nanoplates were synthesized by simple wet chemical method in presence of hexylamine with an intent to improve the visible light mediated photocatalytic activity of ZnO. Powder X-ray diffraction (PXRD) analysis confirmed the integration of AgNPs with ZnO nanoplates. High-resolution transmission electron microscopic (HR-TEM) and X-ray photoelectron spectroscopy (XPS) analysis confirmed the formation of ZnO nanoplates and AgNPs doping. The concentration of Ag in ZnO nanoplates was increased by increasing hexylamine concentration. Ag-ZnO hybrid nanoplates exhibited efficient degradation of organic dyes (methyl orange (MO), methylene blue (MB), Eosin Y (EY) and rhodamine B (RB)) in presence of sun light compared to the pristine ZnO. Further, AgNPs doping with ZnO strongly enhanced anti-biofilm activity and showed strong prevention of colonization. The increase of AgNPs concentration in ZnO nanoplates exhibited enhancement of both photocatalytic and anti-biofilm activity that might be attributed to the improved light absorption in the visible region.

The synergetic enhancement of the porous ZrO2@TiO2 heterostructure and the plasmonic silver nanoparticles for efficient surface‐enhanced Raman scattering

Rapid identification and analysis of pesticide residue on real‐world sample by a portable platform is of growing interest for monitoring food safety and safeguarding human health. Herein, we developed a robust surface‐enhanced Raman spectroscopy (SERS) sensor based on ZrO2@TiO2/Ag substrate for the analysis of pesticide residues. The synergetic effects of the metal organic framework (MOF)‐derived porous ZrO2@TiO2 heterostructure induced charge transfer enhancement and the electromagnetic enhancement from the plasmonic silver nanoparticles (AgNPs) hotspot generate significant SERS enhancement signal. The SERS substrate exhibits superior long‐term stability and signal homogeneity for SERS quantitative analysis. The platform has the capability to detect not only model molecule of 4‐ATP but also pesticides of triazophos and fonofos at the extremely low concentration of 10−8 M. Moreover, we simulate the quantitative detection of pesticide residue on real objects by spraying pesticides on dendrobium and chrysanthemum leaves, followed by transferring to the SERS platform to perform analysis. The nearly linear fitting curve with a wide concentration range suggests the superior qualitative detection capability. Remarkably, two components and three components of the pesticides are readily identified in a rapid way. The approach provides the rapid analysis, low‐cost device, and portable and quantitative pesticide identification and offers a clear path to multicomponent analysis at a trace level.

Defect-enriched red phosphorus nanosheets as efficient and stable photothermal absorber material for interfacial solar desalination

The development of efficient photothermal materials has gained increasing attention for solar thermal-energy conversion. A good photothermal material has a strong light-absorption property, low thermal conductivity, high wettability, and high solar-to-thermal conversion efficiency. In this study, we prepared uniform, sub-micron, and defect-rich red phosphorus (RP) nanosheets via a simple ball-milling method to demonstrate their efficient and durable solar steam generation properties. Three RPs of different sizes were prepared by controlling the milling time (0 h: RP0, 30 h: RP30, and 60 h: RP60). Notably, RP60 exhibited the smallest particle (lateral) size, nanosheet morphology, and defect-rich surface. Furthermore, RP60 exhibited the distinctive properties of a small band gap (1.44 eV), low thermal conductivity (0.07 W/m·K), and low heat capacity (0.66 J/g·K) with exceptional wettability. With simulated sunlight illumination (100 mW/cm2, 1 sun), the RP60 photothermal absorber demonstrated a high water evaporation rate of 1.34 kg/m2·h with a stable solar steam generation efficiency of 74.1 % for over 10 h. A one-dimensional water path and porous polyurethane support facilitated the water supply, large contact area, heat localization, and steam escape. By employing plasmonic resonance-heating silver nanoparticles on the RP60, we achieved a significantly improved solar steam generation efficiency of over 96.0 % and a water evaporation rate of 1.75 kg/m2·h. This study highlights the critical role of morphology, particle size, and defects control in improving the photothermal properties for efficient and durable interfacial seawater desalination.

Broad-band-enhanced and minimal hysteresis perovskite solar cells with interfacial coating of biogenic plasmonic light trapping silver nanoparticles

ABSTRACT Perovskite solar cells (PSCs) have evolved into a viable potential alternative energy source due to their cost-effectiveness and simple fabrication techniques. Despite the immense research interest attracted by PSCs, their rooftop application remains constrained by their low efficiency and hysteretic nature. To address these issues, in this paper, the introduction of silver metallic nanoparticles (AgNPs) with plasmonic effect was achieved by an experimental approach to stimulate the generation and transport of charge carriers, which subsequently results to minimal hysteresis and broadband-enhanced plasmonic devices. Due to the far-field light scattering effect, AgNPs improve the light-trapping of the devices. As a result, electrical characteristics and light absorption are significantly enhanced, leading to broadband increase in photovoltaic performance. With the introduction of one coating cycle of AgNPs, the highest power conversion efficiency (PCE) of the perovskite solar cells increases from a reference value of 4.543 to 10.856%. The fill factor (FF) of such a device was 0.650, the current density (J sc) was 18.998 mA/cm2, and voltage (V oc) was 0.879 V. This device shows an improvement of ~139.0% in PCE, ~61.7% in FF, ~43.7% in J sc and ~2.8% in V oc over the pristine device that lacks AgNPs. The findings of this study contribute to further insight and understanding of plasmonic PSCs by offering useful references and recommendations for PSCs with noble metal NPs incorporation.

Enhancing Evanescent Wave Coupling of Near-Surface Waveguides with Plasmonic Nanoparticles.

Evanescent field excitation is a powerful means to achieve a high surface-to-bulk signal ratio for bioimaging and sensing applications. However, standard evanescent wave techniques such as TIRF and SNOM require complex microscopy setups. Additionally, the precise positioning of the source relative to the analytes of interest is required, as the evanescent wave is critically distance-dependent. In this work, we present a detailed investigation of evanescent field excitation of near-surface waveguides written using femtosecond laser in glass. We studied the waveguide-to-surface distance and refractive index change to attain a high coupling efficiency between evanescent waves and organic fluorophores. First, our study demonstrated a reduction in sensing efficiency for waveguides written at their minimum distance to the surface without ablation as the refractive index contrast of the waveguide increased. While this result was anticipated, it had not been previously demonstrated in the literature. Moreover, we found that fluorescence excitation by waveguides can be enhanced using plasmonic silver nanoparticles. The nanoparticles were also organized in linear assemblies, perpendicular to the waveguide, with a wrinkled PDMS stamp technique, which resulted in an excitation enhancement of over 20 times compared to the setup without nanoparticles.

Antibacterial Activity of the Green Synthesized Plasmonic Silver Nanoparticles with Crystalline Structure against Gram-Positive and Gram-Negative Bacteria.

Nanoparticles (NPs) have attracted considerable interest in numerous fields, including agriculture, medicine, the environment, and engineering. The use of green synthesis techniques that employ natural reducing agents to reduce metal ions and form NPs is of particular interest. This study investigates the use of green tea (GT) extract as a reducing agent for the synthesis of silver NPs (Ag NPs) with crystalline structure. Several analytical techniques, including UV-visible spectrophotometry, Fourier transform infrared (FTIR) spectroscopy, high-resolution transmission electron microscopy (HR-TEM), and X-ray diffraction (XRD), were used to characterize the synthesized Ag NPs. The results of UV-vis revealed that the biosynthesized Ag NPs exhibited an absorbance plasmonic resonance peak at 470 nm. According to FTIR analyses, the attachment of Ag NPs to polyphenolic compounds resulted in a decrease in intensity and band shifting. In addition, the XRD analysis confirmed the presence of sharp crystalline peaks associated with face-centered cubic Ag NPs. Moreover, HR-TEM revealed that the synthesized particles were spherical and 50 nm in size on average. The Ag NPs demonstrated promising antimicrobial activity against Gram-positive (GP) bacteria, Brevibacterium luteolum and Staphylococcus aureus, and Gram-negative (GN) bacteria, Pseudomonas aeruginosa and Escherichia coli, with a minimal inhibitory concentration (MIC) of 6.4 mg/mL for GN and 12.8 mg/mL for GP. Overall, these findings suggest that Ag NPs can be utilized as effective antimicrobial agents.

Nanowatt-Level Photoactivated Gas Sensor Based on Fully-Integrated Visible MicroLED and Plasmonic Nanomaterials.

Photoactivated gas sensors that are fully integrated with micro light-emitting diodes (µLED) have shown great potential to substitute conventional micro/nano-electromechanical (M/NEMS) gas sensors owing to their low power consumption, high mechanical stability, and mass-producibility. Previous photoactivated gas sensors mostly have utilized ultra-violet (UV) light (250-400nm) for activating high-bandgap metal oxides, although energy conversion efficiencies of gallium nitride (GaN)LEDs are maximized in the blue range (430-470nm). This study presents a more advanced monolithic photoactivated gas sensor based on a nanowatt-level, ultra-low-power blue (λpeak = 435 nm) µLED platform (µLP). To promote the blue light absorbance of the sensing material, plasmonic silver (Ag) nanoparticles (NPs) are uniformly coated on porous indium oxide (In2 O3 ) thin films. By the plasmonic effect, Ag NPs absorb the blue light and spontaneously transfer excited hot electrons to the surface of In2 O3 . Consequently, high external quantum efficiency (EQE, ≈17.3%) and sensor response (ΔR/R0 (%) = 1319%) to 1ppm NO2 gas can be achieved with a small power consumption of 63nW. Therefore, it is highly expected to realize various practical applications of mobile gas sensors such as personal environmental monitoring devices, smart factories, farms, and home appliances.