Photon Absorption Capability Research Articles

Eggshell-enhanced composites: Innovative radiation shielding materials for diagnostic X-ray applications

Concrete, a widely-utilized construction material for diagnostic room, heavily relies on Portland cement which is a major contributor to carbon emissions. Thus, this study focused on replacing cement with combination with clay (bentonite and kaolin) and eggshell powder (ESP) as possible shielding materials for diagnostic x-rays. 2 cm blocks are made from combination of clay-ESP, clay-cement and cement-ESP with replacement portions of 0%, 25%, 50% and 75%. Radiation shielding parameters (RAR, LAC, MAC and HVL) of these samples are investigated using a general x-ray machine at 60, 80, 100 and 120 kVp. In addition, elemental composition and compressive strength test are also performed on the blocks. As a result, between all combination, cement-ESP shows the highest RAR, LAC and MAC, however addition of ESP in cement did not show a significant photon absorption capability. Meanwhile, addition of ESP in the mixing portion for both clay results the RAR and MAC to increase due to presence of Si and Ca element in the blocks. In addition, clay-cement combination shows comparable shielding properties value and compressive strength to pure cement block. Therefore, since the objective of this study is to substitute cement with an environmentally friendly material, this particular combination is adequate for serving as a protective barrier for diagnostic purposes.

Investigating a batch-flow photocatalytic LED system for diclofenac removal in wastewater treatment plants: Assessing the influence of reaction conditions on photocatalytic efficiency

This work introduces an innovative batch-flow photocatalytic LED system aimed at efficiently removing diclofenac from wastewater. The study highlights the novelty of fabricating TiO2-loaded carbon fiber photocatalysts through a hydrothermal process, exhibiting a blue shift in their absorption spectrum and enhancing their photon absorption capability. A crucial design feature is the spectral matching between the LED light source and the photocatalyst, which is critical for achieving high photodegradation efficiency. A significant innovation of our study is the testing of the system under real conditions at an operational sewage treatment plant. Here, the designed system demonstrated high efficacy in degrading diclofenac across various treatment stages, highlighting its robustness and adaptability to changing environmental conditions. The highest degradation efficiency was achieved with sewage from the secondary settling tank, where nearly 90 % efficiency was observed after 6 h of irradiation. Moreover, the use of renewable energy sources emphasizes the system's sustainability, presenting a greener alternative to traditional wastewater treatment methods. The investigation not only showcases the system's effectiveness in diclofenac degradation but also its adaptability and stability under real-world conditions, marking a significant advancement in sustainable wastewater treatment technologies.

Adsorption, excitation analysis, and the mechanism of tetracycline photodegradation by Ca12O12-PEDOT, Mg12O12-PEDOT, and Zn12O12-PEDOT hybrid materials: Perspective from first-principles study

Tetracycline (TC) residues threaten aquatic ecosystems by infiltrating water bodies and disrupting aquatic life, potentially affecting the food chain. In our quest to address this ecological concern, we embarked on a fascinating investigation exploring the photodegradation of tetracycline using nanocomposite materials: Ca12O12-PEDOT, Mg12O12-PEDOT, and Zn12O12-PEDOT within the framework of density functional theory (DFT) at the ωB97XD/def2svp method. The results obtained showed that tc@Ca12O12-PEDOT composite exhibited unparalleled stability with an adsorption distance of 1.922 Å, surpassing its counterparts tc@Mg12O12-PEDOT and tc@Zn12O12-PEDOT. The tc@Ca12O12_PEDOT system displayed a compact energy gap, suggesting its superior photon absorption capability from the valence band compared to the others. The sequential order of stabilization energies was observed as follows: Zn12O12-PEDOT > Mg12O12-PEDOT > Ca12O12-PEDOT, with values of 73.26 kcal/mol, 49.35 kcal/mol, and 10.66 kcal/mol, respectively. The analysis of charge transfer showed that tc@Mg12O12_PEDOT had the highest magnitude of charge transfer, followed by tc@Zn12O12_PEDOT and tc@Ca12O12_PEDOT. The characterization of the hole and electron separation through the computed back donation revealed a distinct pattern: tc@Zn12O12_PEDOT > tc@Mg12O12_PEDOT > tc@Ca12O12_PEDOT. The presence of t-index >0 indicated substantial hole and electron separation due to charge transfer. The investigation into hole and electron distribution exhibited a small Hole Distribution Index (HDI), signifying a narrow spatial extent of this charge separation. The order of spatial extent was found to be tc@Zn12O12_PEDOT > tc@Ca12O12_PEDOT > tc@Mg12O12_PEDOT. Similar conclusions can be drawn for the Electron Distribution Index (EDI). When comparing tc@Mg12O12_PEDOT with tc@Ca12O12_PEDOT, we observed a fascinating redshift in the first excited state (41.83 nm), second excited state (27.01 nm), and third excited state (7.59 nm).

Downshifting luminescence amplification by multi-phase energy harvesting

Lanthanide-based luminescent nanoprobe with the second near-infrared (NIR-II) emission under NIR excitation is widely used in deep tissue bioimaging, biological detection, drug delivery, cancer therapy and information storage due to their unique advantages, such as deep penetration depth, tunable lifetime, and emission wavelength. However, due to the small absorption cross-section and low brightness, the practical application of NIR-II luminescent lanthanide nanoprobe remains a formidable challenge. Here, we present an unconventional nanoparticle design that incorporates co-sensitization along with an additional exterior energy harvesting mechanism. This design expands the energy capture pathway, maximizes the NIR photon absorption capability of as-synthesized nanocrystals, and facilitates energy hopping within Yb3+ sublattices, resulting in remarkably amplified downshifting NIR-II emission from Yb3+ at 980 nm under 808 nm excitation. This study introduces a sophisticated heterogeneous nanostructure that can bring about significant improvements in their photophysical properties, offering promising prospects in the field.

Stitching electron localized heptazine units with “carbon patches” to regulate exciton dissociation behavior of carbon nitride for photocatalytic elimination of petroleum hydrocarbons

The electron localized heptazine units make it difficult to separate photoinduced electeron-hole pairs for graphitic carbon nitride (g-C3N4), which limits the application prospect of graphitic-like carbon nitride. Changing inherent N-(C)3 bridging mode of in-plane heptazine units and built more electron channel could be a reasonable strategy. Herein, “carbon patches” were introduced to stitch heptazine units, high speed electron transfer path were thus constructed due to delocalized p orbital electron in “carbon patches” as a result. Simultaneously, interlayers’ high speed electron transfer channel was also constructed by distorted molecular layer because of presence of large electronegative interstitial phosphorus atoms. Such photoinduced electron-holes’ spatial separation in-plane and interlayers were built concurrently and confirmed by XANES and DFT calculation for the first time. The resulted PCCNv series photocatalysts exhibited superior photon absorption capability, excellent charge carriers’ separation kinetics, good O2 molecule adsorption as well as activation capability, the resulted abundant reactive radicals contributed to petroleum hydrocarbons photocatalytic degradation significantly. This work shed light on efficient separation of photoinduced excition for carbon nitride in photocatalysis, simultaneously presented a promising candidate non-metal photocatalytic environmental material for marine oil spill remediation.

Studies on the silver incorporated titania aerogel nanostructure as a photoanode in quasi solid dye- sensitized solar cells

Dye-sensitized solar cells (DSSC) have a significant impact on photovoltaic technology because of their quick, low-cost manufacture, light weight, and high power conversion efficiency (PCE). Numerous research works were undergone on different titania nanostructure used as photoanode in DSSC. High surface area titania nanoarchitecture has effective for more dye absorption to improve the cell performance. Titania aerogels have a high specific surface area and high porosity compared to other titania nanostructures. Incorporation of noble metals into titania aerogel enhanced PCE. In noble metals, silver has promising material because of its cost-effective, less ohmic resistance etc. compared to Au. In this work, we prepared silver doped titania aerogel and studied its photovoltaic performance in the quasi solid DSSC performance. Silver-incorporated titania aerogel was synthesized by the facile sol–gel route. Structural, optical, photovoltaic properties and cell stability of a prepared photoanode material were measured. PXRD revealed that the anatase phase is retained after the incorporation of silver. HRSEM images and EDS spectra confirmed the interconnecting network of titania aerogel and the presence of silver respectively. Due to the Localized Surface Plasmonic Resonance (LSPR) effect, the absorption spectra of the composite exhibited a red-shift around 650 nm. PL spectra showed the decreasing intensity in composites which is the evidence of suppressing electron-hole recombination and improving electron injection. The incorporation of silver has improved the photon absorption capability of the photoanode tends to enhance photocurrent density as well as PCE of QS-DSSC.

Enhanced H2 evolution and the interfacial electron transfer mechanism of titanate nanotube sensitized with CdS quantum dots and graphene quantum dots

Synergistic the modulation of photon absorption capability and interfacial charge transfer of the photocatalyst are highly required for developing high-performance heterojunction photocatalysts. The ternary CdS-graphene quantum dots-titanate nanotubes (CdS-GQDs-TNTs) nanocomposite have been prepared by an in situ growth method. The physicochemical characterization reveals that the GQDs are firmly decorated on both inner and outer surface of TNT through the formation of Ti–O–C chemical bonding, and CdS QDs are loaded on the outer surface of TNTs through strong interfacial interaction. The intimate integrated CdS-GQDs-TNTs nanocomposite exhibits much superior photocatalytic performance toward H2 production compared with binary GQDs-TNTs and pure TNTs photocatalyst, which can be attributed to the combined interaction of the stronger visible light harvesting, the longer lifetime of photogenerated electron−hole pairs, faster interfacial charge transfer rate, fast and long-distance electron transport pass. The interfacial charge transfer mechanism of CdS-GQDs-TNTs ternary composite are proposed based on photoelectrochemical measurements.

Large-scale, broadband absorber based on three-dimensional aluminum nanospike arrays substrate for surface plasmon induced hot electrons photodetection

Performance of plamson induced hot electrons-based photodetectors largely relies on the photon absorption capability. To improve the optical absorption, many perfect absorbers based on the periodic metallic nanostructures have been designed and fabricated through low-throughput, costly and time-consuming lithographic processes, which seriously limit the future potential applications of plasmonic hot electrons optoelectronics devices. Here, a large-scale, broadband absorber consisting of ITO film, ZnO layer, Au film and Al nanospike array substrate was designed and fabricated for hot electrons-based photodetection. The new designed absorber’s absorptivity can be up to 70% in the broad wavelength range from 400 nm to 800 nm (even up to 90% in the wavelength range from 400–550 nm) and most of the absorption comes from the Au film, which is effective for the generation of hot electrons. The enhanced broadband absorption is ascribed to the surface plasmon polariton mode and localized surface plasmon resonance mode supported by the nanospike arrays. The influence of geometry and material parameters on the optical absorption properties is also specifically investigated through numerical simulation. The efficient and broadband absorption of a nanospikes device results in a much larger photocurrent compared with that of a planar reference device. Our approach, which is compatible with large-scale manufacturing, paves the way for the practical implementation of hot electrons-based optoelectronic devices.

Surface Engineering of Defective Hematite Nanostructures Coupled by Graphene Sheets with Enhanced Photoelectrochemical Performance

The major challenge in improving the photoelectrochemical performance of Fe2O3 lies on increasing the photon absorption capability and the charge transfer efficiency. In this work, we facilely mane...

Plasmon hybridisation of self-assembled 3d multiphase nano-titanium oxide towards broadband photon absorption

Nanomaterials with a broadband photon absorption capability are essential for better performing solar cells. Plasmonic nanostructures and Quantum Dots, often fabricated via complex time intensive methods, have a narrow absorption spectrum. In this paper, we report a plasmon hybridised self-assembled 3D nano network of multiphase titanium oxide, which was synthesised via a single step bottoms-up method, and is structurally both multi-layered and three dimensional in nature. The surface plasmonic effect was induced on the self-assembled nanomaterial through its hybridisation with Au and Au/palladium alloy that resulted in the achievement of an enhanced and broadened absorption spectrum extending over the entire visible as well as the near infrared region of the solar spectrum. Further studies were also carried out to examine the impact of various factors like the size, composition and degree of hybridisation of the self-assembled 3D multiphase nano titanium oxide network on its photon absorption capability.

Facile synthesis of TiO2/ZnFe2O4 nanocomposite by sol-gel auto combustion method for superior visible light photocatalytic efficiency

Photocatalytic composite materials having photon absorption capability in the range of visible light were synthesized by loading TiO2 (5, 10, 15, and 20 wt%) on ferrite nanocomposites by sol-gel auto-combustion method. The synthesized nanocomposites were analyzed using X-ray diffraction, Transmission electron microscopy, diffuse reflectance spectroscopy and N2 adsorption techniques. The generation of photo active hydroxyl radicals for all the synthesized composites was found higher under the irradiation of red LED (RLED irradiation) which was confirmed by degradation of rhodamine B dye under irradiation of RLED. Photocatalytic activity of the synthesized nanocomposites was also carried out under irradiation of ultraviolet (UVLED) and blue (BLED) light emitting diodes, which is comparatively less than for the reaction under red LED irradiation. The operational parameters like catalyst amount, pH and concentration of dye solution were studied and ESI-MS degradation pathway is proposed by analyzing the degraded samples.

Enhanced conversion efficiency in nanocrystalline solar cells using optically functional patterns

The lower conversion efficiency of nanocrystalline silicon (nc-Si:H) solar cells is a result of its lower photon absorption capability of nc-Si:H. To increase photon absorption of nc-Si:H, the Ag substrates were fabricated with optically functional patterns. Two types of patterns, with random and regular structures, were formed by direct imprint technology. Owing to these optically functional patterns, the scattering of reflected light at the surface of the patterned Ag was enhanced and the optical path became longer. Thus, a greater amount of photons was absorbed by the nc-Si:H layer. Compared to flat Ag (without a surface pattern), the light absorption value of the nc-Si:H layer with a random structure pattern was increased at wavelengths ranging from 600 to 1100nm. In the case of the regular patterned Ag, the light absorption value of the nc-Si:H layer was higher than the flat Ag at 300 to 1100nm. Subsequently, nc-Si:H solar cells constructed on the optically functional pattern exhibit a 15.7% higher Jsc value and a 19.5% higher overall conversion efficiency, compared to an identical solar cell on flat Ag.

Performance enhancement of thin-film amorphous silicon solar cells with low cost nanodent plasmonic substrates

Performance of thin film photovoltaics largely relies on photon absorption capability. Here, we introduce a novel substrate with patterned aluminum nanodent arrays with unique light management capability. Hydrogenated amorphous silicon thin film solar cells have been fabricated on the nano-texturized substrate for optical property study and photovoltaic performance evaluation. Our measurements have shown significant enhancement on broadband light absorption using these patterned substrates via both geometrical light trapping and plasmonic coupling. Particularly, the enhancement factor reaches as high as 5–30 times at wavelength near the band edge. Numerical simulations confirm the measurements and uncover the mechanisms of the enhancement. More importantly, photovoltaic measurements on nanodent solar cells present improvements of over 31% and 27% in short circuit current and energy conversion efficiency respectively compared with planar solar cells. Therefore, the novel patterned substrates are promising candidates for low cost and high performance thin film solar cells.

Backward stimulated Bragg scattering in multiphoton active CdTexSe1−x quantum dots system

The backward stimulated Bragg scattering (SBgS) of CdTe(x)Se(1-x) quantum dots in chloroform is investigated at three pump laser wavelengths (532, 816, and 1064 nm) in nanosecond regime. The spectral and temporal structures of the backward stimulated scattering and pump threshold dependence on the concentration are presented in this paper. The energy conversion efficiency from input pump pulse to SBgS pulse was measured to be >or=14%. In addition, the samples exhibit multi- (two-, three-)photon absorption capability over the spectral range we investigated. More importantly, both mechanisms of SBgS and multiphoton absorption provided an enhanced optical limiting performance. The measured nonlinear transmissivity was changed from approximately 0.73 to approximately 0.17 for 532 nm laser pulses and from approximately 0.9 to approximately 0.35 for 816 nm laser pulses when the input pulse energy was changed from 10 to approximately 1500 microJ.