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Ultraviolet (UV) detectors have important applications in many fields. ZnO is an excellent semiconductor material for the preparation of UV detectors because of its large direct gap in forbidden bandwidth, its intrinsic response band in the UV region, and its high exciton binding energy. In this paper, high-performance ZnO thin films with the optically advantageous nonpolar structure were prepared by using an atomic layer deposition, and the dominant crystal plane gradually changes from the amorphous phase to the (100) crystal plane. The conventional photoconductor structure ZnO UV detector was enhanced by the surface plasmon exciton effect of Ag nanostructure. When the operating voltage is 5 V and the response light is 350 nm, there is a maximum optical responsiveness of up to 131 A/W. The UV/visible rejection ratio can reach 1824 times. When the ZnO thin film deposition thickness is 400 deposition cycles and about 72 nm, the ZnO thin film UV detector obtains the highest responsiveness (5 V, 365 nm) of 365 A/W. Comparing the photovoltaic performance of the ZnO thin-film detector with the enhanced ZnO thin-film detector and its optimal response wavelength, it is found that the enhanced ZnO thin-film detector increased the photoresponse value by about 100 times. The optimal response wavelength in the UV region is blue-shifted, and the UV-visible rejection ratio and optical response rate are significantly improved. [ABSTRACT FROM AUTHOR]

Band bending modification of metal/semiconductor hybrid nanostructures requires low-cost and effective designs in photoelectrochemical (PEC) water splitting. To this end, it is evinced that gradient doping of Au nanoparticles (NPs) inwards the ZnO nanorods (NRs) through thermal treatment facilitated faster transport of the photo-induced charge carriers. Systematic PEC measurements show that the resulting gradient Au-doped ZnO NRs yielded a photocurrent density of 0.009 mA/cm2 at 1.1 V (vs. NHE), which is 2.5-fold and 8-fold improved compared to those of Au-sensitized ZnO and the as-prepared ZnO NRs, respectively. The IPCE and ABPE efficiency tests confirmed the boosted photoresponse of gradient Au-incorporated ZnO NRs, particularly in the visible spectrum due to the synergistic surface plasmonic effect of Au NPs. A gradient Au dopant profile promoted the separation and transfer of the photo-induced charge carriers at the electrolyte interface via more upward band bending according to the elaborated electrochemical impedance spectroscopy and Kelvin probe force microscopy analyses. Therefore, this research presents an economical and facile strategy for preparing gradient plasmonic noble NP-incorporated semiconductor NRs, which have excellent potential in energy conversion and storage technologies. [ABSTRACT FROM AUTHOR]

In this paper, a two-dimensional structure of thin-layer silicon solar cells with a combination of silver nanoparticle arrays and a blazed grating is introduced. Applying Ag nanoparticles in the top surface of thin-layer solar cells imrpoves the coefficient of light transmission into the active layer and photon absorption because of the resonance surface plasmon effect. By using the FDTD method, the transmittance and absorption of light at both surfaces is investigated. The effect of such structural parameters as radius, distance of nanoparticles, angle of blazed grating and the grating constant has been reported. Finally, both surfaces are combined and the weighted mean values of the light absorbed by active layer are calculated. The results show that the light trapping efficiency can be improved under specified combinations of the structural parameters.

Band bending modification of metal/semiconductor hybrid nanostructures requires low-cost and effective designs in photoelectrochemical (PEC) water splitting. To this end, it is evinced that gradient doping of Au nanoparticles (NPs) inwards the ZnO nanorods (NRs) through thermal treatment facilitated faster transport of the photo-induced charge carriers. Systematic PEC measurements show that the resulting gradient Au-doped ZnO NRs yielded a photocurrent density of 0.009 mA/cm2 at 1.1 V (vs. NHE), which is 2.5-fold and 8-fold improved compared to those of Au-sensitized ZnO and the as-prepared ZnO NRs, respectively. The IPCE and ABPE efficiency tests confirmed the boosted photoresponse of gradient Au-incorporated ZnO NRs, particularly in the visible spectrum due to the synergistic surface plasmonic effect of Au NPs. A gradient Au dopant profile promoted the separation and transfer of the photo-induced charge carriers at the electrolyte interface via more upward band bending according to the elaborated electrochemical impedance spectroscopy and Kelvin probe force microscopy analyses. Therefore, this research presents an economical and facile strategy for preparing gradient plasmonic noble NP-incorporated semiconductor NRs, which have excellent potential in energy conversion and storage technologies.

Photocatalysis is an effective technology for NO removal even at low concentrations in the ambient atmosphere. However, the low efficiency of this advanced process and the tendency of producing toxic byproducts hinder the practical application of photocatalysis. To overcome these problems, the Bi@Ba2TiO4/BaBi4Ti4O15 photocatalytic composites were successfully prepared by a one-step hydrothermal method. The as-synthesized photocatalysts exhibited an efficient photocatalytic performance and generated low amounts of toxic byproducts. X-ray diffraction studies show that Bi3+ is successfully reduced on the surface of Ba2TiO4/BaBi4Ti4O15 (BT/BBT). After L-Ascorbic acid (AA) modification, the photocatalytic NO removal efficiency of Bi@Ba2TiO4/BaBi4Ti4O15 is increased from 25.55% to 67.88%, while the production of the toxic byproduct NO2 is reduced by 92.02%, where the initial concentration of NO is diluted to ca. 800 ppb by the gas stream and the flow rate is controlled at 301.98 mL·min−1 in a 150 mL cylindrical reactor. Furthermore, ambient humidity has little effect on the photocatalytic performance of theBi@Ba2TiO4/BaBi4Ti4O15, and the photocatalyst exhibits excellent reusability after repeated cleaning with deionized water. The improved photocatalytic effect is attributed to the addition of AA in BT/BBT being able to reduce Bi3+ ions to form Bi nanoparticles giving surface plasmon effect (SPR) and generate oxygen vacancies (OVs) at the same time, thereby improving the separation efficiency of photogenerated carriers, enhancing the light absorption, and increasing the specific surface areas. The present work could provide new insights into the design of high-performance photocatalysts and their potential applications in air purification, especially for NO removal.

This work examined the possibility of overcoming narrow band optical absorption of organic dyes in the range of 350–700nm via surface plasmon effect mediated by RF‐sputtered tungsten (W) thin film on mesoporous TiO2 for dye‐sensitised solar cells (DSSCs) application. The UV–visible spectroscopic measurement showed optical absorption of W‐film in the spectral range of 350–700nm with a dominant characteristic feature in the range of 350–550nm. W‐thin film‐coated TiO2 was used as an electron acceptor in DSSCs and observed ∼28% enhancement in short circuit current density compared to that of in a pristine TiO2‐based DSSC which did not use W‐thin film on TiO2. It is attributed to the local field‐induced enhancement in optical absorption which resulted in improved exciton generation and effective charge transport in DSSCs enabled by W‐thin film coating onto mesoporous TiO2. [ABSTRACT FROM AUTHOR]

An important direction in the development of X-ray computed tomography sensors in systems with increased scanning speed and spatial resolution is the creation of an array of miniature current sources. In this paper, we describe a new material based on gold nanostars (GNS) embedded in nanoscale diamond-like carbon (DLC) films (thickness of 20 nm) for constructing a pixel current source with photoinduced electron emission. The effect of localized surface plasmon resonance in GNS on optical properties in the wavelength range from UV to near IR, peculiarities of localization of field and thermal sources, generation of high-energy hot electrons, and mechanisms of their transportation in vacuum are investigated. The advantages of the proposed material and the prospects for using X-ray computed tomography in the matrix source are evaluated.

In this paper, we propose a design process for a plasmonic grating structure to induce the resonance at a target wavelength. In a specific condition, surface gratings may induce the surface plasmon propagation due to the diffraction and the resonance wavelength of the surface plasmon propagation is dependent on the grating shape. The grating configuration was designed by the topology optimization scheme based on the reaction-diffusion equation. To shift the resonance wavelength to the target wavelength, this paper maps the frequency response function to a probability distribution function (PDF). The mean value from the PDF becomes a part of the objective function and the design objective is set to minimize the distance between the present resonance wavelength and the target wavelength while keeping the energy intensity. The process of simulation and optimization was performed using the commercial package COMSOL combined with MATLAB programming. [ABSTRACT FROM AUTHOR]

Constructing the semiconductor heterojunction photocatalyst is the most promising method for environmental pollutant degradation. In this work, solid-state direct z-scheme MoS 2 /Au/g-C 3 N 4 heterojunction nanocomposites with different percentages of MoS 2 (2%, 4%, and 6%) were successfully prepared by hydrothermal and impregnation processes. Under sunlight irradiation, this direct z-scheme heterojunction nanocomposites act as an efficient photocatalyst for the degradation of Methylene blue (MB) and 2, 4-Dicholorophenol (2, 4-DCP) in 60 min. The gold nanoparticles (AuNPs) were deposited on the surface of g-C 3 N 4 was confirmed by TEM analysis. The highest photocatalytic activity of 6%MoS 2 /Au/g-C 3 N 4 exhibited 100% degradation of MB (10 mg/L) within 60 min. A significant improvement in degradation activity was obtained by the efficient separation and transfer of photogenerated charge carriers. Also, radical trapping analysis and EPR results confirmed that the O 2 •– plays an important role in MB degradation. Similarly, the 2, 4-DCP herbicide was found to be degraded (40%) within 60 min. These findings demonstrate that depending on the loading quantity of MoS 2 , the MoS 2 /Au/g-C 3 N 4 nanocomposites exhibit increased photocatalytic activity for the degradation of these pollutants in comparison to bare g-C 3 N 4. [Display omitted] • Solid-state direct z-scheme MoS 2 /Au/g-C 3 N 4 heterojunction nanocomposites were synthesized. • 6%MoS 2 /Au/g-C 3 N 4 exhibits better photocatalytic pollutants degradation under natural sunlight. • Lifetime decay profile data confirm the suppressed recombination of the charge carrier process. • Photocurrent response, impedance data, and ESR analysis supports the enhanced photocatalytic activity. [ABSTRACT FROM AUTHOR]

• Synergistics effects of Fe 3 O 4 nanoparticles and Au nanolayer in solar evaporation. • Solar steam fluxes of 3.76 kg m−2 h−1 by Fe 3 O 4 /Au photoabsorber under 3 sun. • Reduction of brackish well water's salinity to below the drinking water standards. For the first time, we investigated the synergistic effect of Fe 3 O 4 nanoparticles (NPs) and Au nanolayer in interfacial solar steam generation (ISSG) of well water. Herein, single- or double- layer photoabsorbers were prepared by coating poplar wood with different concentrations of Fe 3 O 4 NPs and/or various thicknesses of Au nanolayer. The maximum evaporation efficiency for the single-layer photoabsorber composed of Fe 3 O 4 was 80% under 3 sun (1 sun=1 kW m−2) illumination. The most efficient single-layer photoabsorber coated by Au nanolayer resulted in the evaporation efficiency of 83.2% under 3 sun. The double-layer photoabsorber of Fe 3 O 4 over Au nanolayer (Fe 3 O 4 /Au) and Au layer over Fe 3 O 4 (Au/Fe 3 O 4) were prepared. The Fe 3 O 4 /Au reached the evaporation efficiency of 88.7% and the evaporation rate of 3.76 kg m−2 h−1 under 3 sun due to the synergistic effects of surface plasmon effect in Au NPs as well as black color and visible light absorbing ability of Fe 3 O 4 NPs. [Display omitted] [ABSTRACT FROM AUTHOR]

The plasmonic amorphous MoO 3−x nanodots/g-C 3 N 4 nanosheets were successfully fabricated using ultrasonic cavitation. Owing to deriving from the localized Anderson tail states of a-MoO 3−x , the synergy of ordered architecture and the formed built-in electric field, the constructed Z-scheme heterostructures exhibit high photocatalytic water splitting activity and good photothermal conversion efficiency. [Display omitted] • Plasmonic amorphous MoO 3−x nanodots/g-C 3 N 4 nanosheets were fabricated. • Z-scheme heterostructure exhibits high photocatalytic water splitting performance. • Z-scheme heterostructure delivers good photothermal conversion efficiency. • Enhanced performance is due to the localized Anderson tail states of a-MoO 3−x. Semiconductor-based plasmonic materials have attracted extensive attention for photocatalytic systems. However, their photocatalytic reactions are hindered by limited light-harvesting ability and the transfer rate of photo-generated electrons. Herein, vacancy engineering and phase engineering are rationally integrated to develop amorphous molybdenum oxide (a-MoO 3−x) nanodots anchored on g-C 3 N 4 as a highly active photocatalyst. Through high localized surface plasmon resonance (LSPR) effect of a-MoO 3−x nanodots and tunable electrical properties induced by the heterostructural interface, the Z-scheme a-MoO 3−x /g-C 3 N 4 heterostructure demonstrates broadband absorption and the excited photo-generated electrons. Further theoretical calculations demonstrate that the enhancement of photocatalytic and photothermal performance is mainly attributed to the highly localized Anderson tail states of a-MoO 3−x. Consequently, the a-MoO 3−x /g-C 3 N 4 heterostructure exhibits a photocurrent density of ∼36.5 μA cm−2, which is about 2.7 and 4.1 times higher than that of pure g-C 3 N 4 nanosheets (∼13.5 μA cm−2) and a-MoO 3−x nanodots (∼9 μA cm−2), respectively. The photocatalytic performance enhancement relying on defects and long-range disorder of a-MoO 3−x in Z-scheme heterostructure is explored. [ABSTRACT FROM AUTHOR]

We report on the upconversion emission of Sm 3+ ions doped tellurite glass in the presence of Yb 3+ ions and silver nanoparticles. The enhancement of infrared-to-visible upconversion emissions is achieved under 980 nm excitation wavelength and attributed to the high absorption cross section of Yb 3+ ions and an efficient energy transfer to Sm 3+ ions. Further enhancements are attributed to the plasmonic effect via metallic nanoparticles resulting in the large localized field around rare earth ions. However, under excitation at 406 nm, the addition of Yb 3+ content and heat-treated silver nanoparticles quench the luminescence of Sm 3+ ions likely due to quantum cutting and plasmonic diluent effects, respectively. [ABSTRACT FROM AUTHOR]

Band bending modification of metal/semiconductor hybrid nanostructures requires low-cost and effective designs in photoelectrochemical (PEC) water splitting. To this end, it is evinced that gradient doping of Au nanoparticles (NPs) inwards the ZnO nanorods (NRs) through thermal treatment facilitated faster transport of the photo-induced charge carriers. Systematic PEC measurements show that the resulting gradient Au-doped ZnO NRs yielded a photocurrent density of 0.009 mA/cm 2 at 1.1 V (vs. NHE), which is 2.5-fold and 8-fold improved compared to those of Au-sensitized ZnO and the as-prepared ZnO NRs, respectively. The IPCE and ABPE efficiency tests confirmed the boosted photoresponse of gradient Au-incorporated ZnO NRs, particularly in the visible spectrum due to the synergistic surface plasmonic effect of Au NPs. A gradient Au dopant profile promoted the separation and transfer of the photo-induced charge carriers at the electrolyte interface via more upward band bending according to the elaborated electrochemical impedance spectroscopy and Kelvin probe force microscopy analyses. Therefore, this research presents an economical and facile strategy for preparing gradient plasmonic noble NP-incorporated semiconductor NRs, which have excellent potential in energy conversion and storage technologies.

In this study, we developed a new way to increase the efficiency of dye-sensitized solar cells by using TiO2/silver/carbon nanotube composites as the working electrode. Silver nanoparticles and multi-walled carbon nanotubes were mixed with TiO2 nanoparticles and used as working electrodes in a dye-sensitized solar cell. The effect of the silver nanoparticles and multi-walled carbon nanotubes on the efficiency of the dye-sensitized solar cell was studied as function of their volume fractions using several microscopic and spectroscopic characterization techniques such as scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, ultra-violet-vis and electrochemical impedance spectroscopy. It was found that the silver nanoparticles could induce surface plasmonic phenomena, where the light absorption was enhanced in the ultra-violet wavelength range. Additionally, the carbon nanotubes could increase the electron mobility in the working electrode due to their high surface-to-volume ratio and superior electrical conductivity. The efficiency of the silver/carbon nanotube/TiO2 nanocomposite working electrode was compared with that of a conventional TiO2 working electrode under one-sun illumination (100 mWcm–2, AM 1.5 G). The TiO2/Ag/carbon nanotube nanocomposite working electrode had a two-fold higher efficiency (3.76%) than the conventional pure TiO2 working electrode (1.88%). [ABSTRACT FROM PUBLISHER]

In this paper, we propose waveguide design at infrared wavelength with asymmetric dielectric surface gratings. Surface gratings are able to generate the surface plasmon polariton effect at the outlet of radiated light through an aperture. The property and the shape of gratings are key factors behind generating collimated beams from subwavelength slits or holes surrounded by corrugated surfaces. Grating design is conducted by structural optimization based on the phase field method. The design objective is set to maximize the Poynting vector in the measuring area, and it is focused on finding a clear shape of grating structure for the manufacturing feasibility to be taken into account. The simulation and optimization process is performed by using the commercial package COMSOL associated with the MATLAB programming. [ABSTRACT FROM AUTHOR]

Composites of electrospun poly(ethylene oxide) (PEO) fibers and silver nanoparticles (Ag NPs) were used as a soft template for coating with TiO2 by atomic layer deposition (ALD). Whereas the as-deposited TiO2 layers on PEO fibers and Ag NPs were completely amorphous, the TiO2 layers were transformed into polycrystalline TiO2 nanotubes (NTs) with embedded Ag NPs after calcination. Their plasmonic effect can be controlled by varying the thickness of the dielectric Al2O3 spacer between Ag NPs and dye molecules by means of the ALD process. Electronic and spectroscopic analyses demonstrated enhanced photocurrent generation and solar-cell performance due to the intense electromagnetic field of the dye resulting from the surface plasmon effect of the Ag NPs. [ABSTRACT FROM AUTHOR]

Abstract: Photocatalysis has attracted significant interest to solve both the energy crisis and effectively combat environmental contamination. However, as the most widely used photocatalyst, titania (TiO2) suffers from inefficient utilization of solar energy due to its wide band gap. In the present paper, we describe a method to extend the absorption edge of photocatalyst to visible region by the surface plasmon effect of silver. Silver ions are photo-reduced onto the surface of titanate nanotubes, which are synthesized by a conventional hydrothermal method. The as-synthesized Ag/titanate composite is transformed into Ag/titania nanoparticles by annealing at different temperatures. It is found that the interaction of Ag nanoparticles with the supports (titanate/titania) plays a key role for the visible light activity. The samples annealed at low temperature (<350°C) do not show significant activity under our conditions, while the one annealed at 450°C shows fast-degradation of methyl orange (MO) under visible light irradiation. The detailed mechanisms are also discussed. [Copyright &y& Elsevier]

In recent years, nanostructures have improved the performance of solar cells and are regarded as the most promising microstructures. The optical properties of PEDOT:PSS/c-Ge hybrid solar cells (HSCs) based on the octagon germanium nanoparticles (O-GNPs) were numerically analyzed using the finite-difference time-domain (FDTD) method. The optimal structure of the hybrid solar cell is determined by changing the thickness of the organic layer and structural parameters of nanoparticles to enhance the optical absorption and eventually achieve high broadband absorption. By changing the structure parameter of O-GNPs, we studied its effect on solar cells. The optimization of geometric parameters is based on maximum absorption. The light absorption of our optimized HSCs is basically above 90% between 200 and 1500 nm. PEDOT:PSS is placed on top of O-GNPs to transmit the holes better, allowing O-GNPs to capture a lot of photons, to increase absorbance value properties in the AM1.5 solar spectral irradiated region. The transmittance is increased by adding poly-methyl methacrylate (PMMA). At the same time, the electrical characteristics of Ge solar cells were simulated by DEVICE, and short-circuit current (Jsc), open-circuit voltage (Voc), maximum power (Pmax), filling coefficient (FF) and photoelectric conversion efficiency (PCE) were obtained. According to the optimization results after adjusting the structural parameters, the maximum short-circuit current is 44.32 mA/cm2; PCE is 7.84 mW/cm2; FF is 69%. The results show that the O-GNPs have a good light trapping effect, and the structure design has great potential for the absorption of HSCs; it is believed that the conversion efficiency will be further improved through further research. [ABSTRACT FROM AUTHOR]

An important direction in the development of X-ray computed tomography sensors in systems with increased scanning speed and spatial resolution is the creation of an array of miniature current sources. In this paper, we describe a new material based on gold nanostars (GNS) embedded in nanoscale diamond-like carbon (DLC) films (thickness of 20 nm) for constructing a pixel current source with photoinduced electron emission. The effect of localized surface plasmon resonance in GNS on optical properties in the wavelength range from UV to near IR, peculiarities of localization of field and thermal sources, generation of high-energy hot electrons, and mechanisms of their transportation in vacuum are investigated. The advantages of the proposed material and the prospects for using X-ray computed tomography in the matrix source are evaluated. [ABSTRACT FROM AUTHOR]

Abstract: We report on the spectral tunability of white light by localized surface plasmon (LSP) effect in a colour converting hybrid device made of CdSe/ZnS quantum dots (QDs) integrated on InGaN/GaN blue light-emitting diodes (LEDs). Silver (Ag) nanoparticles (NPs) are mixed with QDs for generating LSP effect. When the plasmon absorption of Ag NPs is synchronized to the QW emission at 448nm, the NPs selectively absorb the blue light and subsequently enhance the QD emission. Using this energy transfer scheme, the (x, y) chromaticity coordinates of the hybrid white LED was tuned from (0.32,0.17) to (0.43,0.26), and thereby generated warm white light emission with correlated colour temperature (CCT) around 1800K. Moreover, a 47% enhancement in the external quantum efficiency (EQE) was realized. [Copyright &y& Elsevier]