Additional file 1: of Mesoporous Nickel Oxide (NiO) Nanopetals for Ultrasensitive Glucose Sensing

Supporting information. (PDF 521 kb

TiO₂–Co₃O₄ Core–Shell Nanorods: Bifunctional Role in Better Energy Storage and Electrochromism

A suitably designed heterostructured TiO₂–Co₃O₄ core–shell nanorod array has been found to exhibit improved supercapacitive as well as electrochromic properties as compared to the nanowires of either of the oxides when used individually. The core–shell nanostructures have been grown on an FTO coated glass substrate by preparing TiO₂ nanorods through hydrothermal reaction followed by growing a Co₃O₄ shell layer by electrodeposition. The core–shell electrode shows high specific and areal capacitance of ∼342 F/g and ∼140 mF/cm² (at scan rate of 100 mV/s), respectively. Such an improvement in supercapacitive behavior, as compared to the behavior of the existing ones, is likely due to increased surface area and modified charge dynamics within the core–shell heterojunction. Additionally, these core–shells also exhibit stable and power efficient bias induced color change between transparent (sky blue) and opaque (dark brown) states with coloration efficiency of ∼91 cm²/C. Porous morphology and strong adhesion to the surface of transparent conducting glass electrode give rise to superior cyclic stability in both energy storage and electrochromic applications, which make these core–shell structures suitable candidates for future electronic devices

TiO₂–Co₃O₄ Core–Shell Nanorods: Bifunctional Role in Better Energy Storage and Electrochromism

A suitably designed heterostructured TiO₂–Co₃O₄ core–shell nanorod array has been found to exhibit improved supercapacitive as well as electrochromic properties as compared to the nanowires of either of the oxides when used individually. The core–shell nanostructures have been grown on an FTO coated glass substrate by preparing TiO₂ nanorods through hydrothermal reaction followed by growing a Co₃O₄ shell layer by electrodeposition. The core–shell electrode shows high specific and areal capacitance of ∼342 F/g and ∼140 mF/cm² (at scan rate of 100 mV/s), respectively. Such an improvement in supercapacitive behavior, as compared to the behavior of the existing ones, is likely due to increased surface area and modified charge dynamics within the core–shell heterojunction. Additionally, these core–shells also exhibit stable and power efficient bias induced color change between transparent (sky blue) and opaque (dark brown) states with coloration efficiency of ∼91 cm²/C. Porous morphology and strong adhesion to the surface of transparent conducting glass electrode give rise to superior cyclic stability in both energy storage and electrochromic applications, which make these core–shell structures suitable candidates for future electronic devices

Fano Scattering: Manifestation of Acoustic Phonons at the Nanoscale

Size-dependent asymmetric low-frequency Raman line shapes have been observed from silicon (Si) nanostructures (NSs) due to a quantum confinement effect. The acoustic phonons in Si NSs interact with an intraband quasi-continuum to give rise to Fano interaction in the low-frequency range. The experimental asymmetric Raman line shape has been explained by developing a theoretical model that incorporates the quantum-confined phonons interacting with an intraband quasi-continuum available in Si NSs as a result of discretization of energy levels with unequal separation. We discover that a phenomenon similar to Brillouin scattering is possible at the nanoscale in the low-frequency regime and thus may be called “Fano scattering” in general. A method has been proposed to extract information about nonradiative transitions from the Fano scattering data where these nonradiative transitions are involved as an intraband quasi-continuum in modulation with discrete acoustic phonons

Organic Nanostructures on Inorganic Ones: An Efficient Electrochromic Display by Design

Improved electrochromism has been reported from a hybrid nanoheterostructure-based array designed using transition-metal oxides and conducting polymers. An improvement in color contrast, coloration efficiency, and operating voltage makes these hybrid core–shell-type nanostructures (NSs) suitable for power efficient and reversible electrochromic applications showing switching between transparent and opaque states rather than resulting in colored/bleached switching. Nanopetals (NPs) of nickel oxide have been used as the backbone to grow nanohemispheres (NHs) of polyaniline onto a fluorine-doped tin oxide electrode using a two-step synthesis methodology consisting of a hydrothermal method, followed by an electrodeposition method. The coaxial NPs/NHs core–shell arrays exhibit a better electrochromic performance compared to their individual constituents. Devices fabricated using these hybrid NSs show power efficient optical switching between transparent and opaque with fast response and a good cycle life of approximately 1500. The coloration efficiency of the fabricated device has been calculated to be more than 145 cm²/C and an optical modulation of more than 45%

Organic Nanostructures on Inorganic Ones: An Efficient Electrochromic Display by Design

Improved electrochromism has been reported from a hybrid nanoheterostructure-based array designed using transition-metal oxides and conducting polymers. An improvement in color contrast, coloration efficiency, and operating voltage makes these hybrid core–shell-type nanostructures (NSs) suitable for power efficient and reversible electrochromic applications showing switching between transparent and opaque states rather than resulting in colored/bleached switching. Nanopetals (NPs) of nickel oxide have been used as the backbone to grow nanohemispheres (NHs) of polyaniline onto a fluorine-doped tin oxide electrode using a two-step synthesis methodology consisting of a hydrothermal method, followed by an electrodeposition method. The coaxial NPs/NHs core–shell arrays exhibit a better electrochromic performance compared to their individual constituents. Devices fabricated using these hybrid NSs show power efficient optical switching between transparent and opaque with fast response and a good cycle life of approximately 1500. The coloration efficiency of the fabricated device has been calculated to be more than 145 cm²/C and an optical modulation of more than 45%

Organic Nanostructures on Inorganic Ones: An Efficient Electrochromic Display by Design

Improved electrochromism has been reported from a hybrid nanoheterostructure-based array designed using transition-metal oxides and conducting polymers. An improvement in color contrast, coloration efficiency, and operating voltage makes these hybrid core–shell-type nanostructures (NSs) suitable for power efficient and reversible electrochromic applications showing switching between transparent and opaque states rather than resulting in colored/bleached switching. Nanopetals (NPs) of nickel oxide have been used as the backbone to grow nanohemispheres (NHs) of polyaniline onto a fluorine-doped tin oxide electrode using a two-step synthesis methodology consisting of a hydrothermal method, followed by an electrodeposition method. The coaxial NPs/NHs core–shell arrays exhibit a better electrochromic performance compared to their individual constituents. Devices fabricated using these hybrid NSs show power efficient optical switching between transparent and opaque with fast response and a good cycle life of approximately 1500. The coloration efficiency of the fabricated device has been calculated to be more than 145 cm²/C and an optical modulation of more than 45%

Spectral Anomaly in Raman Scattering from p‑Type Silicon Nanowires

An anomalous nature of Raman spectral asymmetry has been reported here from silicon nanowires (SiNWs) prepared from a heavily doped p-type Si wafer using a metal induced etching technique. Raman spectra of SiNWs prepared from two p-type Si wafers with different doping levels show different behaviors in terms of asymmetry as characterized by the asymmetry ratio. The SiNWs prepared from high doped p-type wafer show an anomaly in asymmetry in addition to the red shift and broadening of the Raman line shape due to the presence of the “FAno-quaNTUM” (FANTUM) effect. The heavy doping in the wafer provides a continuum of energy states to be available to interact with confined optic phonons which results in electron–phonon interaction. SiNWs prepared from low doped p-type wafer show a red shift and asymmetric broadening due to the quantum confinement effect alone. Careful analysis has been provided to clearly understand the role of Fano and quantum effects in p-type SiNWs with high doping and their relative contribution in Raman line-shape half-widths. A theoretical framework for supporting the presence of the FANTUM effect has also been proposed to show that how a system with appropriate Fano and quantum effects’ relative contribution may result in a near-symmetric Raman line shape

Quantifying the Short-Range Order in Amorphous Silicon by Raman Scattering

Quantification of the short-range order in amorphous silicon has been formulized using Raman scattering by taking into account established frameworks for studying the spectral line-shape and size dependent Raman peak shift. A theoretical line-shape function has been proposed for representing the observed Raman scattering spectrum from amorphous-Si-based on modified phonon confinement model framework. While analyzing modified phonon confinement model, the term “confinement size” used in the context of nanocrystalline Si was found analogous to the short-range order distance in a-Si thus enabling one to quantify the same using Raman scattering. Additionally, an empirical formula has been proposed using bond polarizability model for estimating the short-range order making one capable to quantify the distance of short-range order by looking at the Raman peak position alone. Both the proposals have been validated using three different data sets reported by three different research groups from a-Si samples prepared by three different methods making the analysis universal