More Like this

1. A Comparative Study of Structural, Optical and Electrical Properties of Fe-ZnO Nanoparticles Synthesized by Precipitation and Microwave Method for Photovoltaic Applications

   https://doi.org/10.21926/jept.2103035  

   Neupane, Ganga R. ; Kaphle, Amrit ; Mcllroy, David N. ; Echeverria, Elena ; Sankaran, Prasanna ; Hari, Parameswar ( May 2021 , Journal of Energy and Power Technology)

   Iron doped ZnO (Fe-ZnO) nanoparticles were synthesized using two techniques that are economical as well as scalable to yield tunable properties of nanoparticles for facilitating down conversion in an absorbing layer of a solar cell. To evaluate the suitability of Fe-ZnO nanoparticles prepared by two deposition methods, we present a comparison of optical, electrical, and structural properties of Fe-ZnO using several experimental techniques. Structural properties were analyzed using transmission electron microscopy and x-ray diffraction spectroscopy (XRD) with Rietveld analysis for extracting information on compositional variations with Fe doping. The chemical composition of nanoparticles was analyzed through X-ray photoelectron spectroscopy (XPS). The optical properties of nanoparticles were studied using photoluminescence and UV-Vis absorption spectroscopy. In addition, fluorescence lifetime measurement was also performed to study the changes in an exponential decay of lifetimes. The electrical transport properties of Fe-ZnO were analyzed by impedance spectroscopy. Our studies indicate that ethanol as a solvent in a microwave method would produce smaller nanoparticles up to the size of 11 nm. In contrast, the precipitation method produces secondary phases of Fe2O3 beyond 5% doping. In addition, our studies show that the optical and electrical properties of resulting Fe-ZnO nanoparticles depend on the particle sizes and themore »synthesis techniques used. These new results provide insight into the role of solvents in fabricating Fe-ZnO nanoparticles by precipitation and microwave methods for photovoltaic and other applications.« less
2. Cascade synthesis and optoelectronic applications of intermediate bandgap Cu3VSe4 nanosheets

   https://doi.org/10.1038/s41598-020-78649-9  

   Liu, Mimi ; Lai, Cheng-Yu ; Zhang, Meng ; Radu, Daniela R. ( December 2020 , Scientific Reports)

   Two-dimensional (2D) ternary materials recently generated interest in optoelectronics and energy-related applications, alongside their binary counterparts. To date, only a few naturally occurring layered 2D ternary materials have been explored. The plethora of benefits owed to reduced dimensionality prompted exploration of expanding non-layered ternary chalcogenides into the 2D realm. This work presents a templating method that uses 2D transition metal dichalcogenides as initiators to be converted into the corresponding ternary chalcogenide upon addition of copper, via a solution-phase synthesis, conducted in high boiling point solvents. The process starts with preparation of VSe₂nanosheets, which are next converted into Cu₃VSe₄sulvanite nanosheets (NSs) which retain the 2D geometry while presenting an X-ray diffraction pattern identical with the one for the bulk Cu₃VSe₄. Both the scanning electron microscopy and transmission microscopy electron microscopy show the presence of quasi-2D morphology. Recent studies of the sulfur-containing sulvanite Cu₃VS₄highlight the presence of an intermediate bandgap, associated with enhanced photovoltaic (PV) performance. The Cu₃VSe₄nanosheets reported herein exhibit multiple UV–Vis absorption peaks, related to the intermediate bandgaps similar to Cu₃VS₄and Cu₃VSe₄nanocrystals. To test the potential of Cu₃VSe₄NSs as an absorber for solar photovoltaic devices, Cu₃VSe₄NSs thin-films deposited on FTO were subjected to photoelectrochemical testing, showing p-type behavior andmore »stable photocurrents of up to ~ 0.036 mA/cm². The photocurrent shows a ninefold increase in comparison to reported performance of Cu₃VSe₄nanocrystals. This proves that quasi-2D sulvanite nanosheets are amenable to thin-film deposition and could show superior PV performance in comparison to nanocrystal thin-films. The obtained electrical impedance spectroscopy signal of the Cu₃VSe₄ NSs-FTO based electrochemical cell fits an equivalent circuit with the circuit elements of solution resistance (R_s), charge-transfer resistance (R_ct), double-layer capacitance (C_dl), and Warburg impedance (W). The estimated charge transfer resistance value of 300 Ω cm²obtained from the Nyquist plot provides an insight into the rate of charge transfer on the electrode/electrolyte interface.

   « less
3. Replication Data for: Protein Secondary Structure in Spider Silk Nanofibrils

   https://doi.org/10.7910/DVN/GMEEYL  

   Schniepp, Hannes C. ; Wang, Qijue ; McArdle, Patrick ; Wang, Stephanie L. ; Wilmington, Ryan L. ; Xing, Zhen ; Greenwood, Alexander ; Cotten, Myrian L. ; Qazilbash, M. Mumtaz ( January 2022 )

   Abstract

   This dataset contains raw data, processed data, and the codes used for data processing in our manuscript from our Fourier-transform infrared (FTIR) spectroscopy, Nuclear magnetic resonance (NMR), Raman spectroscopy, and X-ray diffraction (XRD) experiments. The data and codes for the fits of our unpolarized Raman spectra to polypeptide spectra is also included. The following explains the folder structure of the data provided in this dataset, which is also explained in the file ReadMe.txt. Browsing the data in Tree view is recommended. Folder contents Codes Raman Data Processing: The MATLAB script file RamanDecomposition.m contains the code to decompose the sub-peaks across different polarized Raman spectra (XX, XZ, ZX, ZZ, and YY), considering a set of pre-determined restrictions. The helper functions used in RamanDecomposition.m are included in the Helpers folder. RamanDecomposition.pdf is a PDF printout of the MATLAB code and output. P Value Simulation: 31_helix.ipynb and a_helix.ipynb: These two Jupyter Notebook files contain the intrinsic P value simulation for the 31-helix and alpha-helix structures. The simulation results were used to prepare Supplementary Table 4. See more details in the comments contained. Vector.py, Atom.py, Amino.py, and Helpers.py: These python files contains the class definitions used in 31_helix.ipynb and a_helix.ipynb. See more details in the comments contained. FTIR FTIR Raw Transmission.opj: This Origin data file contains the raw transmission data measured on single silk strand and used for FTIR spectra analysis. FTIR Deconvoluted Oscillators.opj: This Origin data file was generated from the data contained in the previous file using W-VASE software from J. A. Woollam, Inc. FTIR Unpolarized MultiStrand Raw Transmission.opj: This Origin data file contains the raw transmission data measured on multiple silk strands. The datasets contained in the first two files above were used to plot Figure 2a-b and the FTIR data points in Figure 4a, and Supplementary Figure 6. The datasets contained in the third file above were used to plot Supplementary Figure 3a. The datasets contained in the first two files above were used to plot Figure 2a-b, FTIR data points in Figure 4a, and Supplementary Figure 6. NMR Raw data files of the 13C MAS NMR spectra: ascii-spec_CP.txt: cross-polarized spectrum ascii-spec_DP.txt: direct-polarized spectrum Data is in ASCII format (comma separated values) using the following columns: Data point number Intensity Frequency [Hz] Frequency [ppm] Polypeptide Spectrum Fits MATLAB scripts (.m files) and Helpers: The MATLAB script file Raman_Fitting_Process_Part_1.m and Raman_Fitting_Process_Part_2.m contains the step-by-step instructions to perform the fitting process of our calculated unpolarized Raman spectrum, using digitized model polypeptide Raman spectra. The Helper folder contains two helper functions used by the above scripts. See the scripts for further instruction and information. Data aPA.csv, bPA.csv, GlyI.csv, GlyII.csv files: These csv files contain the digitized Raman spectra of poly-alanine, beta-alanine, poly-glycine-I, and poly-glycine-II. Raman_Exp_Data.mat: This MATLAB data file contains the processed, polarized Raman spectra obtained from our experiments. Variable freq is the wavenumber information of each collected spectrum. The variables xx, yy, zz, xz, zx represent the polarized Raman spectra collected. These variables are used to calculate the unpolarized Raman spectrum in Raman_Fitting_Process_Part_2.m. See the scripts for further instruction and information. Raman Raman Raw Data.mat: This MATLAB data file contains all the raw data used for Raman spectra analysis. All variables are of MATLAB structure data type. Each variable has fields called Freq and Raw, with Freq contains the wavenumber information of the measured spectra and Raw contains 5 measured Raman signal strengths. Variable XX, XZ, ZX, ZZ, and YY were used to plot and sub-peak analysis for Figure 2c-d, Raman data points in Figure 4a, Figure 5b, Supplementary Figure 2, and Supplementary Figure 7. Variable WideRange was used to plot and identify the peaks for Supplementary Figure 3b. X-Ray X-Ray.mat: This MATLAB data file contains the raw X-ray data used for the diffraction analysis in Supplementary Figure 5.
   More>>
4. Synthesis of SERS-active core–satellite nanoparticles using heterobifunctional PEG linkers

   https://doi.org/10.1039/D1NA00676B  

   San Juan, Angela Michelle ; Chavva, Suhash Reddy ; Tu, Dandan ; Tircuit, Melanie ; Coté, Gerard ; Mabbott, Samuel ( December 2021 , Nanoscale Advances)

   Surface-enhanced Raman scattering (SERS) is a sensitive analytical technique capable of magnifying the vibrational intensity of molecules adsorbed onto the surface of metallic nanostructures. Various solution-based SERS-active metallic nanostructures have been designed to generate substantial SERS signal enhancements. However, most of these SERS substrates rely on the chemical aggregation of metallic nanostructures to create strong signals. While this can induce high SERS intensities through plasmonic coupling, most chemically aggregated assemblies suffer from poor signal reproducibility and reduced long-term stability. To overcome these issues, here we report for the first time the synthesis of gold core–satellite nanoparticles (CSNPs) for robust SERS signal generation. The novel CSNP assemblies consist of a 30 nm spherical gold core linked to 18 nm satellite particles via linear heterobifunctional thiol–amine terminated PEG chains. We explore the effects that the varying chain lengths have on SERS hot-spot generation, signal reproducibility and long-term activity. The chain length was varied by using PEGs with different molecular weights (1000 Da, 2000 Da, and 3500 Da). The CSNPs were characterized via UV-Vis spectrophotometry, transmission electron microscopy (TEM), ζ -potential measurements, and lastly SERS measurements. The versatility of the synthesized SERS-active CSNPs was revealed through characterization of optical stability and SERS enhancementmore »at 0, 1, 3, 5, 7 and 14 days.« less
5. Synthesis, Spectroscopic Characterization and Applications of Tin Dioxide

   https://doi.org/https://doi.org/10.1007/978-3-030-62761-4_11  

   Alghamdi, Hawazin ; Concepcion, Benjamin ; Baliga, Shankar ; and Misra, Prabhakar ( December 2020 , Chapter in Book: Contemporary Nanomaterials in Material Engineering Applications)

   Mubarak, Nabisab M. ; Walvekar, Rashmi ; Arshid, Numan ; and Khalid, Mohammad (Ed.)

   Metal oxides are useful for the detection and sensing of combustible and toxic gases, and for use in lithium batteries and solar cells. The present study focuses on the spectroscopic investigation of commercial and in-house laboratory synthesized tetragonal tin dioxide (SnO2), aimed at studying its physical and chemical properties at nanoscale levels and in bulk. We have investigated the pure powder form and thin films prepared on two different types of substrate, silicon and UV-Quartz, each with five different thicknesses (i.e. 41, 78, 96.5, 373, and 908 nm). Raman spectroscopy with two different laser excitation wavelengths, namely 780 and 532 nm, has been used to investigate the various SnO2 vibrational modes. Thermal effects on the primary vibrational features in the Raman spectra have been studied in the range 30–170 °C. X-ray diffraction (XRD) spectra have been recorded to confirm the rutile structure of tin dioxide and to obtain information on the spherical grain particle size of SnO2 with EDS analysis for the thin film samples. Scanning Electron Microscope (SEM) images have been recorded in order to understand the morphology of the particles of SnO2 at the nanoscale level. In addition, FT-IR spectra have been obtained to study the IR-active vibrationalmore »modes for the bulk and thin film samples on the two substrates. Moreover, UV-VIS spectra have been employed to determine the energy band gap for the SnO2 film samples by an efficient process facilitated by a Tauc plot technique utilizing an in-house developed python script.« less