Intense visible emission from ZnO/PAAX (X = H or Na) nanocomposite synthesized via a simple and scalable sol-gel method

Bottom Deposition Enables Stable All-Solid-State Batteries with Ultrathin Lithium Metal Anode

Modern strides in energy storage underscore the significance of all-solid-state batteries (ASSBs) predicated on solid electrolytes and lithium (Li) metal anodes in response to the demand for safer batteries. Nonetheless, ASSBs are often beleaguered by non-uniform Li deposition during cycling, leading to compromised cell performance from internal short circuits and hindered charge transfer. In this study, the concept of "bottom deposition" is introduced to stabilize metal deposition based on the lithiophilic current collector and a protective layer composed of a polymeric binder and carbon black. The bottom deposition, wherein Li plating ensues between the protective layer and the current collector, circumvents internal short circuits and facilitates uniform volumetric changes of Li. The prepared functional binder for the protective layer presents outstanding mechanical robustness and adhesive properties, which can withstand the volume expansion caused by metal growth. Furthermore, its excellent ion transfer properties promote uniform Li bottom deposition even under a current density of 6 mA·cm-2. Also, scanning electron microscopy analysis reveals a consistent plating/stripping morphology of Li after cycling. Consequently, the proposed system exhibits enhanced electrochemical performance when assessed within the ASSB framework, operating under a configuration marked by a high Li utilization rate reliant on an ultrathin Li.

High-Performance Self-Powered Quantum Dot Infrared Photodetector with Azide Ion Solution Treated Electron Transport Layer

The demand for self-powered photodetectors (PDs) capable of NIR detection without external power is growing with the advancement of NIR technologies such as LIDAR and object recognition. Lead sulfide quantum dot-based photodetectors (PbS QPDs) excel in NIR detection; however, their self-powered operation is hindered by carrier traps induced by surface defects and unfavorable band alignment in the zinc oxide nanoparticle (ZnO NP) electron-transport layer (ETL). In this study, an effective azide-ion (N3 -) treatment is introduced on a ZnO NP ETL to reduce the number of traps and improve the band alignment in a PbS QPD. The ZnO NP ETL treated with azide ions exhibited notable improvements in carrier lifetime and mobility as well as an enhanced internal electric field within the thin-film heterojunction of the ZnO NPs and PbS QDs. The azide-ion-treated PbS QPD demonstrated a increase in short-circuit current density upon NIR illumination, marking a responsivity of 0.45 A W-1, specific detectivity of 4 × 1011 Jones at 950 nm, response time of 8.2 µs, and linear dynamic range of 112 dB.

Modification in Toxicity of l-Histidine-Incorporated ZnO Nanoparticles toward Escherichia coli

This paper presents a comparative study of the toxicity of pristine-ZnO and l-histidine-incorporated ZnO toward Escherichia coli (E. coli) as a Gram-negative model organism. Pristine-ZnO and l-histidine-incorporated ZnO with different l-histidine concentrations were synthesized using an open aqueous solution bath technique. XRD studies revealed the formation of polycrystalline wurtzite ZnO. The average crystallite size of the synthesized l-histidine-incorporated ZnO decreased as the concentration of l-histidine increased. The FTIR spectra showed the presence of Zn-O, CO2-/CO3-, and C-N (only in l-histidine-incorporated ZnO samples) and -OH bond vibration signals in all samples. The chemical purity of all the samples was ensured using XPS analysis. The microbial activity of these samples was investigated using E. coli. The solution with 100 μg/mL ZnO in sterile distilled water showed up to 94% growth inhibition of E. coli, establishing antibacterial activity. However, l-histidine incorporated in ZnO showed reduced antibacterial activity with the increase of the concentration of l-histidine in ZnO. Furthermore, flow cytometry studies during the interaction of ZnO and E. coli confirmed the generation of reactive oxygen species (ROS), validating its antibacterial activity. The interaction of l-histidine-incorporated ZnO and E. coli showed declining ROS with the increase in the l-histidine concentration, indicating a ZnO toxicity reduction.

Impact on the Photocatalytic Dye Degradation of Morphology and Annealing-Induced Defects in Zinc Oxide Nanostructures

In this study, three different morphologies, nanoflower (NF), nano sponge (NS), and nano urchin (NU), of zinc oxide (ZnO) nanostructures were synthesized successfully via a mild hydrothermal method. After synthesis, the samples were annealed in the atmosphere at 300, 600, and 800 °C. Although annealing provides different degradation kinetics for different morphologies, ZnO NS performed significantly better than other morphologies for all annealing temperatures we used in the study. When the photoluminescence, electron paramagnetic resonance spectroscopy, BET surface, and X-ray diffraction analysis results are examined, it is revealed that the defect structure, pore diameter, and crystallinity cumulatively affect the photocatalytic activity of ZnO nanocatalysts. As a result, to obtain high photocatalytic activity in rhodamine B (RhB) degradation, it is necessary to develop a ZnO catalyst with fewer core defects, more oxygen vacancies, near band emission, large crystallite size, and large pore diameter. The ZnO NS-800 °C nanocatalyst studied here had a 35.6 × 10^-3 min^-1 rate constant and excellent stability after a 5-cycle photocatalytic degradation of RhB.

Raman and X-ray photoelectron spectroscopic investigation of solution processed Alq3/ZnO hybrid thin films

In this study, we characterize the solution processed tris-(8-hydroxyquinoline)aluminum(Alq₃)/ZnO hybrid thin films using Raman and X-ray photoelectron spectroscopic (XPS) techniques. Raman studies reveal the sol-gel derived spin-coated ZnO thin film has hexagonal wurtzite structure. The incorporation of Alq₃ molecules in the hybrid film results in the formation of bonding onto the surface of highly crystalline ZnO nanoparticles. The XPS confirms the incorporation of Alq₃ in the hybrid thin films and corroborates that the Alq₃ molecules may be adsorbed onto the surface of ZnO nanoparticles (chemisorption), showing the existence of chemical interaction between Alq₃ and ZnO in the hybrid films. These studies support that the chemisorbed Alq₃ molecules onto the ZnO nanoparticles may facilitate the charge transfer (non-radiative) between Alq₃ and ZnO in the hybrid thin films which will be useful to enhance the optical and electrical properties for the optoelectronic device applications.

Self-Assembled Hybrid ZnO Nanostructures as Supports for Copper-Based Catalysts in the Hydrogenolysis of Glycerol

This study describes the use of new ZnO/PAAH hybrid nanomaterials (PAAH = polyacrylic acid) as copper catalyst supports for the hydrogenolysis of glycerol. A study of the synthesis parameters (washing process, temperatures of synthesis and calcination) of these hybrid supports has allowed us to vary their morphology and specific surface area and ultimately the sizes and dispersion of the copper nanoparticles, and to perform a general analysis of their effects on the catalytic performance of the materials. All catalysts were synthesized by the urea deposition-precipitation method (DPU) and were fully characterized to establish a structure–activity relationship. Optimization of the synthesis and catalytic conditions allowed remarkable yields/conversions of the order of 70% for selectivities in 1,2 propanediol of 90%.

P3HT-based visible-light organic photodetectors using PEI/PAA multilayers as a p-type buffer layer

A low leakage current is critical for achieving organic photodetectors (OPDs) with high detectivity. The insertion of buffer layers is an effective approach for reducing the reverse-biased leakage current. In this study, polyelectrolyte multilayers comprising polyethyleneimine (PEI) and polyacrylic acid (PAA) were introduced by a spin-assisted layer-by-layer technique into an OPD as a p-type buffer layer. Although PEI/PAA multilayers are insulators, when used as a buffer layer in our device, they suppressed the leakage current and also provided a high photocurrent due to the light-assisted tunneling effect. The prepared device configuration was ITO/(PEI/PAA)2/P3HT:PC60BM/Yb/Al. The performances of the OPDs were investigated by measuring the current-voltage characteristics, external quantum efficiency, and transient photocurrent. In addition, the operating mechanism of the OPDs was confirmed by impedance analysis. The device comprising (PEI/PAA)2 showed a specific detectivity of 3.11 × 1012 Jones and a bandwidth of 103.2 kHz at -1 V and 525 nm. This performance is a numerical value that can be used in devices such as a line scan camera. In addition, because this device is fabricated by a low-temperature solution process, flexible and large-area substrates can be used.

ZnO as a Functional Material, a Review

Zinc oxide (ZnO) is a fascinating wide band gap semiconductor material with many properties that make it widely studied in the material science, physics, chemistry, biochemistry, and solid-state electronics communities. Its transparency, possibility of bandgap engineering, the possibility to dope it into high electron concentrations, or with many transition or rare earth metals, as well as the many structures it can form, all explain the intensive interest and broad applications. This review aims to showcase ZnO as a very versatile material lending itself both to bottom-up and top-down fabrication, with a focus on the many devices it enables, based on epitaxial structures, thin films, thick films, and nanostructures, but also with a significant number of unresolved issues, such as the challenge of efficient p-type doping. The aim of this article is to provide a wide-ranging cross-section of the current state of ZnO structures and technologies, with the main development directions underlined, serving as an introduction, a reference, and an inspiration for future research.

Doping of ZnO inorganic-organic nanohybrids with metal elements

We present a general and in-depth study of the effect of dopants in hybrid inorganic/organic ZnO/PAA (polyacrylic acid) nanocomposites. These dopants vary as much by their ionic size, as by their electronic valence and some of them have been used in ZnO due to their known magnetic and/or optical properties. The chemical nature of the dopants controls their ability to incorporate into ZnO crystal lattice. Three concentrations (0.1%, 1% and 5%) of dopants were studied in order to compare the effect of the concentration with the results obtained previously in the literature. Our results confirm in the first place the trend observed in the literature, that increase in dopant concentration leads to quenching of visible luminescence for ZnO nanocrystals obtained by very different processes. However, the degradation of photoluminescence quantum yield (PL QY) is not inevitable in our nanocomposites. At low doping concentration for some dopants with a small or comparable ionic radius than Zn²⁺, PL QY can be maintained or even improved, making it possible to tune the visible emission spectrum between 2.17 eV and 2.46 eV. This opens up the prospect of synthesizing phosphors without rare earth for white LEDs, whose spectrum can be tuned to render warm or cold white light, by a chemical synthesis process with a low environmental impact.

p-GaN/n-ZnO nanorods: the use of graphene nanosheets composites to increase charge separation in self-powered visible-blind UV photodetectors

ZnO-based heterojunctions have found applications as self-powered ultraviolet photodetectors (PDs). However, high doping levels are not compatible with high mobility for metallic doped ZnO-based PDs so further development has been inhibited. This study demonstrates a method to increase the open-circuit voltage (V _oc) that allows keeping a sufficiently high level of mobility of ZnO, using a ZnO nanorod/GaN heterojunction that incorporates graphene nanosheets as the active layer. These hybrid PDs have triple the value for V _oc of PDs that have only pure ZnO and better exhibit photo-response characteristics. The results of surface Kelvin probe microscopy and x-ray photoelectron spectrometer show that the complex defects that occur because Zn interstitials form a shallow donor in ZnO are mainly responsible for the increase in the value of V _oc. Using this functional nanostructure as an active layer represents a new method for the manufacture of high-performance self-powered PDs.