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Cr3+ doped nanoporous anodic alumina: Facile microwave assisted doping to realize nanoporous ruby and phase dependent photoluminescence
摘要： Microwave-assisted solution technique (MAST) was used for the homogeneous doping of Cr3+ in nanoporous anodic alumina (NAA) which when heat-treated transforms into nanoporous ruby. The rise in annealing temperature led to the phase transition in the sequence: amorphous- δ- θ- α-alumina as evidenced by XRD. The dopant was homogenously distributed as seen from the elemental mapping and the Cr3+ content was 0.5 at%. Di?use re?ectance spectroscopy (DRS) displayed the characteristic blue and green absorption bands and the color-tone varied from light-green at 700 °C to the pink appearance at 1350 °C owing to the dopant di?usion. Two broad photoluminescence (PL) excitation bands centered at ～550 nm and ～400 nm were observed whose intensity increased with the annealing temperature. All the alumina phases exhibited characteristic phase dependent PL showing variation in the luminescence intensity and peak position. The characteristic R-line for α-phase was intense and observed at 694 nm with 4 m s lifetime in accordance with that expected for Ruby. Crystal ?eld parameters were obtained from the PL excitation spectra and Dq/B values were found to be higher than 2.3 for all the phases of NAA con?rming the presence of Cr3+ ions in the strong crystal ?eld. With annealing, the CIE coordinates moved towards the red region. The presented work shows a promising easy and inexpensive method for dopant incorporation into alumina and explores the understanding of phase-dependent emission of Cr3+ doped NAA for their potential applications in the areas of nano-optics and composite luminescent nanomaterials.
关键词： Nanoporous anodic alumina,Cr3+ doping,Photoluminescence,Phase transition
更新于2025-11-21 11:18:25
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Photo-Sensitive Pb5S2I6 Crystal Incorporated Polydopamine Biointerface Coated on Nanoporous TiO2 as an Efficient Signal-on Photoelectrochemical Bioassay for Ultrasensitive Detection of Cr(VI) ions
摘要： An ultrasensitive Visible light-triggered photoelectrochemical (PEC) sensor was designed based on ideal photoactive lead sulfoiodide (Pb5S2I6) as low band gap crystal, which hydrothermally synthesized rapidly at low temperature (160°C) in hydrochloride acid media followed by its incorporation into polydopamine as reactive photo-biointerface, through a facile in situ electropolymerization method, coated on nanoporous TiO2 grown by anodization on Ti foil. The structure of as-prepared samples and their photoelectrochemical properties were fully characterized. This unique photo-sensitive Pb5S2I6 catalyst-based PEC bioassay was constructed for the detection of low-abundant Cr(VI) ion in real samples. Applying central composite design, individual and mutual interaction effects were evaluated to obtain optimized solution pH, applied potential and radiant light wavelength as operational factors influencing the PEC efficiency for Cr(VI) detection. At optimal condition, the proposed sensor due to effective suppress in electron–hole recombinations showed a very low detection limit of 3.0 nM, over a broad linear concentration range of 0.01 μM-80 μM in addition to high sensitivity versus 1.9 μA/μM Cr(VI). Proposed PEC sensor displayed high selectivity, reproducibility and stability as well as improved excitation conversion efficiency, which make it highly applicable using solar energy. The potential applicability of the designed sensor was evaluated in water, tomato juice and hair color.
关键词： Photoelectrochemical biosensor,Nanoporous TiO2,Cr(VI) ions,Visible light excitation.,Pb5S2I6 crystal
更新于2025-11-21 11:01:37
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Transparent Sn-doped In2O3 electrodes with a nanoporous surface for enhancing the performance of perovskite solar cells
摘要： We report on a simple and efficient process to enhance the performance of perovskite solar cells by using ITO electrodes with a nanoporous surface formed by wet-etching of self-agglomerated Ag nanoparticles. Effective removal of the Ag nanoparticles embedded in the surface of the ITO electrodes result in a nanoporous structure without changing the ITO's sheet resistance (10.17 Ω/square) and optical transmittance (89.08%) at a 550 nm wavelength. Examinations with a scanning electron microscope, a transmission electron microscope, and two-dimensional porous mapping show that the nanoporous ITO surface has an increased contact area with the electron transport layer, which enhanced the carrier extraction efficiency of the perovskite solar cells. Compare to perovskite solar cells fabricated on typical ITO with a flat surface morphology, the perovskite solar cells fabricated on the nanoporous-surface ITO show a higher fill factor of 81.1% and a power conversion efficiency of 20.1%. These results indicate that modified ITO surfaces with nano-scale porosity provide a simple and efficient method to improve the power conversion efficiency of perovskite solar cells without a complicated process.
关键词： Contact area,Nanoporous surface,Sn-doped In2O3,Ag agglomeration,Perovskite solar cells
更新于2025-11-21 10:59:37
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Ultrafine Cu2O/CuO nanosheet arrays integrated with NPC/BMG composite rod for photocatalytic degradation
摘要： A free-standing Cu2O/CuO@nanoporous copper/bulk metallic glass (Cu2O/CuO@NPC/BMG) composite rod with a multimodal hierarchical porous structure has been successfully prepared by a facile two-step synthesis strategy consisting of dealloying and anodizing. The NPC/BMG composite is first fabricated by dealloying of Cu50Zr45Al5 BMG rod. Then the ultrafine Cu2O/CuO nanosheet arrays are synthesized by anodizing of the NPC/BMG rod followed by heat treatment. The as-obtained Cu2O/CuO@NPC/BMG composite possesses a multimodal hierarchical porous structure comprising interconnected pores ranging from micro, meso to macro sizes. It is worth pointing out that there are several “barren lands” without nanosheets grown on the surface of the composite. Further analyses indicate that the microstructures of substrate materials not only dominate the sizes of Cu2O/CuO sheets, but also influence the nucleation and growth of Cu2O/CuO sheets. Meanwhile, the possible formation mechanism of the Cu2O/CuO nanosheets is proposed. Accordingly, the Cu2O/CuO@NPC/BMG composite shows remarkably high photocatalytic degradation performance and excellent cycling stability for RhB due to the multimodal hierarchical porous structure, ultrafine Cu2O/CuO nanosheets in the entire NPC and the integration design strategy.
关键词： Metallic glass,Dealloying,Nanoporous,Anodizing,Nanosheet
更新于2025-11-14 17:03:37
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Surface-to-volume ratio drives photoelelectron injection from nanoscale gold into electrolyte
摘要： Hot charge carriers from plasmonic nanomaterials currently receive increased attention due to their promising potential in important applications such as solar water splitting. While a number of important contributions were made on plasmonic charge carrier generation and their transfer into the metal’s surrounding in the last decades, the local origin of those carriers is still unclear. With our study employing a nanoscaled bicontinous network of nanoporous gold, we take a comprehensive look at both subtopics in one approach and give unprecedented insights into the physical mechanisms controlling the broadband optical absorption and the generation and injection of hot electrons into an adjacent electrolyte where they enhance electrocatalytic hydrogen evolution. This absorption behavior is very different from the well-known localized surface plasmon resonance effects observed in metallic nanoparticles. For small ligament sizes the plasmon decay in our network is strongly enhanced via surface collisions of electrons. These surface collisions are responsible for the energy transfer to the carriers, thus, the creation of hot electrons from a broad spectrum of photon energies. As we reduce the gold ligament sizes below 30 nm, we demonstrate an occurring transition from absorption that is purely exciting 5d-electrons from deep below the Fermi level to an absorption which significantly excites “free” 6sp-electrons to be emitted. We differentiate these processes via assessing the internal quantum efficiency of the gold network photoelectrode as a function of the feature size providing a size-dependent understanding of the hot electron generation and injection processes in nanoscale plasmonic systems. We demonstrate that the surface effect - compared to the volume effect – becomes dominant and leads to significantly improved efficiencies. The most important fact to recognize is that in the surface photoeffect presented here, absorption and electron transfer are both part of the same quantum mechanical event.
关键词： Hot electron,Photoemission,Water splitting,Hydrogen evolution,Carrier injection,Surface damping,Nanoporous Au
更新于2025-10-22 19:40:53
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Three Dimensional Structures of NiO Nanoporous/ZnO Nanoarray Film for Enhanced Electrochromic Performance
摘要： An electrochromic device using the as-obtained NiO nanoporous/ZnO nanoarray working electrode was constructed and assembled. NiO nanoporous/ZnO nanoarray three dimensional structures was prepared on ITO glass substrate by a two-step route which combined chemical bath deposition method with hydrothermal method. NiO nanoporous/ZnO nanoarray electrode reveals noticeable improvement of electrochromism compared to unitary NiO nanoporous, including larger optical modulation (81%), higher coloration efficiency (78.5 cm2/C), faster response times (2.6 s and 9.7 s for coloring and bleaching), and favourable durability performance. Such enhancement is mainly attributed to the three dimensional structures of NiO nanoporous coated on ZnO nanoarray. Namely, (1) uniform hexagonal ZnO nanoarray loaded more amount of NiO nanoporous, (2) NiO nanoporous cross-linked with ZnO nanorods provided a loose interspace morphology, (3) stronger adhesion between ZnO nanorods and ITO rested with ZnO seed, (4) core-shell and cross-linked structures promoted electrolyte infiltration, and (5) appropriate bandgap improved the charges transfer.
关键词： NiO nanoporous,ZnO nanorod array,electrochromic,three dimensional
更新于2025-09-23 15:23:52
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Modeling and optimization of characterization of nanostructure anodized aluminium oxide membranes
摘要： This study indicates the importance of statistical analysis and modeling to investigate the synthesis and optimization of anodized aluminium oxide (AAO) properties for template-assisted synthesis of nanostructure particles. The response surface methodology was used to optimize pore size and porosity of AAO. The impacts of four main parameters including type of acidic electrolyte, concentration of acid, bath temperature and electrical potential of anodization on characterization of AAO were investigated. Statistical analysis showed that the linear and quadratic terms of these variables had significant effects. Based on the statistical analysis, a possible mechanism of the anodization was proposed. The proposed mechanism helped us to develop an analytical model. The analytical model could predict the experimental results with an appropriate accuracy. Results indicated the rate-limiting reaction in anodization process is water dissociation which was conducted at the pore bottom of the AAO. In addition, concentrated electrical field at pore base induced water splitting so that the activation energy of water dissociation decreased ten times and reached to 9898.5 J/mol.
关键词： Statistical analysis,Anodized aluminium oxide,Electrochemical synthesis,Pore perforation,Nanoporous materials
更新于2025-09-23 15:23:52
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Stacked Nanoporous Anodic Alumina Gradient-Index Filters with Tunable Multispectral Photonic Stopbands as Sensing Platforms
摘要： This study presents the development and optical engineering of stacked nanoporous anodic alumina gradient-index (NAA-GIFs) filters with tunable multi-spectral photonic stopbands for sensing applications. The structure of these photonic crystal (PC) is formed by stacked layers of NAA produced with sinusoidally modified effective medium. The progressive modification of the sinusoidal period during the anodization process enables the generation and precise tuning of the characteristic photonic stopbands (PSB) (i.e. one per sinusoidal period in the anodization profile) of these PC structures. Four types of NAA-GIFs featuring three distinctive PSBs positioned within the visible spectral region are developed. The sensitivity of the effective medium of these NAA-GIFs is systematically assessed by measuring spectral shifts in the characteristic PSBs upon infiltration of their nanoporous structure with analytical solutions of D-glucose with several concentrations (0.025 – 1 M). This study provides new insights into the intrinsic relationship between the nanoporous architecture of these PCs and their optical properties, generating opportunities to fabricate advanced optical sensing systems for high-throughput and multiplexed detection of analytes in a single sensing platform.
关键词： nanoporous anodic alumina,sensing platforms,stacked,multispectral bands,photonic crystals,gradient index filters
更新于2025-09-23 15:23:52
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Influence of porosity and pore size on sputtering of nanoporous structures by low-energy Ar ions: Molecular dynamics study
摘要： In this paper we have carried out molecular dynamics simulation of the low-energy Ar ion irradiation of nanoporous homogeneous material with different porosity and pore sizes. Our results demonstrate that in a model with small pores (Rpore = 0.8 nm) and relatively low (22%) porosity, the pores at near-surface layers collapsed due to the ion bombardment, whereas in a model with larger pores (Rpore = 2.8 nm) and higher (44%) porosity no significant structural changes occurred under the same irradiation conditions. To study thermal stability of porous structures and to reveal the effects of both the pore radius and the porosity on pore collapsing, our nanoporous structures were subjected to gradual heating. The simulation results demonstrate distinct mechanisms of structural changes in the nanoporous materials depending on the value of the excess surface energy per unit volume.
关键词： low-k dielectrics,plasma treatment,nanoporous material,pore collapse,sputtering
更新于2025-09-23 15:23:52
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[IEEE 2018 14th International Conference on Advanced Trends in Radioelecrtronics, Telecommunications and Computer Engineering (TCSET) - Lviv-Slavske, Ukraine (2018.2.20-2018.2.24)] 2018 14th International Conference on Advanced Trends in Radioelecrtronics, Telecommunications and Computer Engineering (TCSET) - Nanoengineering of anisotropic materials for creating the active optical cells with increased energy efficiency
摘要： In this paper the state-of-the-art for exploiting the unique physical and chemical properties of crystalline nanomaterials and their possible applications for creating optical cells with increased energy efficiency are discussed. Using a method of growing crystals from a solution the KDP and TGS nanocrystals were grown in the mesopores of the Al2O3 matrix where the direction of growth was discussed. To investigate the developed nanocomposites the X-ray analysis was used and it showed the predominant crystal orientation of the KDP and TGS in the direction [001] which coincides with the direction of the cylindrical pores. Thus, the possibility of growing of the KDP and TGS nanocrystals in the mesopores of the Al2O3 matrix was developed and provides the prospect of creating optical cells with increased energy efficiency.
关键词： X-ray analysis,anisotropic materials,crystalline nanocomposites,nanoporous matrices,Al2O3,nanofiller KDP and TGS
更新于2025-09-23 15:23:52