Mechanically rechargeable zinc-air batteries are considered promising for powering electric vehicles due to their high theoretical energy density, but a few practical hurdles impede their implementation. Understanding the key technical blockades that restrict their implementation will enable quick deployment of these batteries in electric vehicles. This Review analyzes the performance of various on-road electric vehicle segments powered by lithium-ion batteries and compares this with the current rechargeable zinc-air battery development. We discuss the theoretical limits and vehicle-specific blockades involved in achieving the performance of mechanically rechargeable zinc-air battery-powered electric vehicles, equivalent to those powered by lithium-ion batteries. Based on the identified blockades, we present ideas on future research direction on positive and negative electrodes, and battery operation and architecture. Finally, we discuss the conditions under which these batteries can be implemented in various electric vehicle segments. Mechanically rechargeable zinc-air batteries are promising for powering electric vehicles but their implementation is restricted. This Review analyzes the performance of lithium-ion battery-powered electric vehicles and applies these thoughts to vehicles powered by rechargeable zinc-air batteries.

Cyanobacteria are known for their efficient oxygenic photosynthesis, capturing solar energy to produce oxygen and organic compounds under various light conditions. In this work, we employed Synechocystis pevalekii cyanobacteria in a DSSC-based device and studied their photoelectrochemical (PEC) properties. The genome-scale metabolic model was simulated under dark and light conditions using MATLAB 2020b's COBRA Toolbox (Gurobi optimizer) to understand the light driven reactions. Guided by these simulations, the PEC devices were made in two different configurations, wherein one, the microbes are free-floating and in the second, they are anchored onto an anode as biofilm. The role of concentration of microbes, their age, conditioning and nutrient media on PEC performance is analysed. Finally, the photocurrent response of a single microbe on an agar-based biofilm was studied with a scanning electrochemical microscope (SECM) using a 1 mu m Pt-tip as the working electrode, under both dark and light conditions. This single microbial device serves as a benchmark to identify or calculate the maximum possible PEC performance from a bulk microbial device.

Hybrid halide perovskite nanocrystals (NCs) have attracted significant attention for application in optoelectronic devices due to their excellent optical properties and low-cost synthesis. Yet their application in optoelectronic devices is limited due to the lack of understanding of their electronic properties. In this study, we investigated the influence of grain multiplicity on the hysteresis of single-grain nanocrystals (SG-NCs), multigrain nanocrystals (MG-NCs), and polycrystalline thin films (PTFs) of all-inorganic CsPbBr3 perovskite. The current-voltage characteristics of lateral ITO/CsPbBr3/ITO devices were analyzed at different scan rates and illumination levels. We found that in PTFs, hysteresis occurs over a wide voltage range due to grain boundaries facilitating ion migration, while the hysteresis is limited to a short voltage range in SG-NCs due to the polarization and ion confinement within the nanocrystals. Interestingly, MG-NCs exhibit long- and short-range hysteresis due to the presence of grain boundaries within the nanocrystal structure, while ions are confined in the nanocrystals. Hence, the presence of a grain boundary influences the hysteresis in the I-V curve. Our study provides a better understanding of the charge transport behavior of perovskite-based materials, which could further aid in developing high-performance perovskite-based memory devices for neuromorphic computing.

The hydrogen evolution reaction (HER) driven by electrocatalytic water splitting is attaining prevalent attention for the manufacturing of clean and green hydrogen energy. Herein, we report the simple one-step hydrothermal synthesis of cobalt sulfide nanoflakes decorated with reduced graphene oxide (CoS/rGO) nanocomposites as an effective electrode material for HER. The CoS/rGO nanocomposites exhibited the rGO nanosheet-decorated hierarchically interconnected CoS nanoflakes structure. The CoS/rGO nanocomposites exhibited an excellent HER activity with a low overpotential of 371 mV and a small Tafel slope of 103 mV/dec. More interestingly, the catalytic stability of CoS/rGO nanocomposites is comparatively higher than the pristine CoS NFs. These results suggest that the facile nanocomposites of CoS/rGO could be a prominent catalytic material for effective green hydrogen production.(c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

In the pursuit of efficient optoelectronics devices, hybrid lead halide perovskite quantum dots (PQDs) have emerged as highly promising semiconductor materials due to their intriguing properties. While these materials have been used in many applications, the fundamental understanding of their behavior remains relatively unexplored, especially for the mixed halide perovskite samples. To facilitate the advancement of PQD technologies for commercial applications, it is essential to gain insights into the role of ion migration. This study delves into the fundamental aspects of ion migration in halide perovskite nanocrystals. Porous electrodes for supercapacitor application were fabricated using CsPbBr3-xIx (x=0,1,2) nanocrystals prepared via the ligand-assisted re-precipitation (LARP) method. Three-electrode electrochemical measurements and several other characterizations were conducted under dark conditions to evaluate device performance and elucidate the impact of mixed halides on device kinetics and stability. X-ray photoelectron spectroscopy before and after the electrochemical measurement reveals intriguing findings. Notably, the analysis uncovered the phase segregation in the metal halide perovskite nanocrystals with particular emphasis on CsPbBr2I due to its distinctive mixed-halide behavior. The specific capacitance increases with the increasing cycles. Interestingly, as the iodide content increases, there is no selective halide expulsion as the structure collapses rapidly. Halide perovskite nanocrystals are promising materials for energy storage applications due to their high surface area and improved stability. However, selective iodine expulsion from the mixed halide perovskite nanocrystals leads to irreversible structural degradation. This article demonstrates that the storage capacity increases as the iodine repulsion increases till there is a structural degradation due to halide ion migration. image

In the present study, a facile and simple hydrothermal technique was employed for the preparation of reduced graphene oxide (rGO) incorporated NiCo2S4 and analyzed the hydrogen evolution reaction (HER) activity in alkaline media. The face centered cubic crystal structure is confirmed from the X-ray diffraction analysis and hexagonal cage like structure of NiCo2S4 was visualized by FESEM analysis. With the increased number of facets in hexagonal cage structure, the electrochemical-active surface area (ECSA) gets increased, and the HER performance gets increased for bare NiCo2S4. The additional ECSA is caused by the existence of rGO in the case of ternary nanocomposite (rGO-NiCo2S4). The obtained small over potential (370 mV) and small Tafel slope (139 mV/dec) proves the excellent HER activity of rGO-NiCo2S4 nanocomposite. The optimized rGO-NiCo2S4 as excellent HER electrocatalyst provides a highly stable polarization curve up to 10 h and it can be more useful to replace the high-cost platinum noble electrocatalyst.(c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Light induced changes in the optoelectronic properties affect the performance and the stability of halide perovskites. In this work, we report the real-time visualization of the photobrightening (PLB) effect using confocal laser scanning microscopy wherein the photon induced enhancement in photoluminescence is observed and their role in conductivity and photovoltaic properties are studied. The methodology is inspired from the Fluorescence Recovery After Photobleaching (FRAP) technique that is traditionally used to study biological cells. The role of composition, and surface/grain boundaries of perovskites, wavelengths, and intensity of illuminating photons, and time of illumination on the photobrightening or photobleaching is thoroughly investigated. The CH3NH3PbI3 exhibits a dominant photobrightening effect, with green photons showing more PLB than blue or red photons. The study of PLB between films and single crystals clearly shows the effect is a surface phenomenon. The presence of mixed iodide/bromide or pure bromide in the halide site and formamidinium or cesium in the A site suppressed the PLB. The strain relaxation in the organic site is found to be responsible for the PLB effect, and it enhanced the overall conductivity in material leading to better photovoltaic performance.

Thehysteresis effects due to electronic-ionic conductivity canbe utilized to develop memory devices for information storage andbrain-like computing. Halide perovskites-based devices exhibit frequenthysteresis in their current-voltage curves, making them suitablefor neuromorphic computing. Despite recent advances in this field,the exact mechanism behind switching between high and low resistivestates in halide perovskite memristors is still under debate. Thisstudy aims to understand the switching mechanism and charge transportin the ITO/MAPbBr(3)/Au device's geometry by analyzingtheir SET-RESET states through current-voltage characteristicsand impedance spectroscopy at different applied biases and under differentlight intensities. A clear shift in the SET voltage due to increasedlight power correlates with the electronic-ionic coupling andion migration. In the impedance spectroscopy measurement, the AC conductivityshows a negative slope at the SET state, especially at the low-frequencyregime due to the ion-induced voltage, which gets screened by photogeneratedcharge carriers.

A highly functional electron transport layer (ETL) is essential for fabricating stable and efficient perovskite solar cells (PvSCs). Among the various n-type materials, mesoporous titanium dioxide (m-TiO2) is the most widely used ETL in combination with a compact layer. Despite contributing to good efficiency devices, low electron mobility, and a high annealing temperature (>450 degrees C) to form a crystalline film in the anatase phase, the use of m-TiO2 is a bottleneck for perovskite technology. Aluminum-doped zinc oxide (AZO) is a potential replacement for m-TiO2 as an ETL due to its relatively high electron mobility, high transparency, and low-temperature processing. Here, we demonstrate a lowtemperature solution-processed TiO2/AZO bilayer thin film as ETL in a planar PvSCs configuration, which exhibits a power conversion efficiency of 13.94% with a JSC of 19.49 mA/cm(2), a VOC of 1.05V, and a FF of 68% with a pixel area of 0.25 cm(2). The unencapsulated TiO2/AZO-ETL-based PvSCs retained 70% of their initial efficiency after 1000 h in an ambient atmosphere. Our studies demonstrated that the solution-processed TiO2/AZO bilayer ETLs provide a promising approach for developing low-temperature, high-performance, and stable planar PvSCs.

Organic-inorganic perovskites have proven to be outstanding solar cell light-absorbing materials due to their spectacular properties such as high tolerance to defects, bandgap tunability, high carrier mobility, long diffusion length, and high absorption coefficient. However, the associated stability issues in harsh conditions hinder their commercial prospects. In addition to the instability of the absorbing perovskite layer, the usage of organic transport layers and its vulnerable interface with the absorbing layer also contributes to the overall instability of the device. Taking a cue from inorganic solar cell counterparts, researchers have now turned their attention to the development of inorganic perovskites to improve the stability of perovskite solar cells (PSCs). Work in this direction has led to power conversion efficiency (PCE) beyond 19% with improved stability. Here, we review the progress made toward the development of all-inorganic perovskite materials and their integration into PSCs as stable absorbers. We have discussed in extensive detail the work done so far for different inorganic perovskite materials, their associated device performance, and stability. Besides this, we have also discussed the integration of inorganic transport layers in PSCs replacing the organic counterparts used traditionally and their effect on the stability of the device. The stability of all-inorganic PSCs under different harsh environmental conditions has also been discussed in detail. Finally, we have presented a summary and outlook on the realization of all-inorganic efficient and stable PSCs toward their commercial adaptability.

A lanthanide-doped inorganic down-shifting nano-phosphor that converts the intense ultra-violet (UV) light photons to visible-light photons is highly attractive for dye-sensitized solar cells (DSSCs) to enhance light harvesting and power conversion efficiencies. In the present research, for the first time, a highly luminescent Ce3+-doped SrF2 (Ce3+:SrF2) nanophosphor is employed as a down-shifting nanophosphor material in the photoanode of DSSC. The nanophosphor was synthesized by co-precipitation technique, followed by a rapid microwave calcination approach. The structural and morphological properties of the synthesized nanophosphor are investigated by X-ray diffraction, Xray photoelectron spectroscopy, field emission scanning electron microscopy, and transmission electron microscopy analyses. The optical absorption and emission characteristics of the Ce3+:SrF2 down-shifting nanophosphor are investigated. Interestingly, the nanophosphor displayed a broad luminescence in the visible region under UV wavelength excitation. Absorption studies show that the Ce3+:SrF2 nanophosphor absorbs the deep-UV and near-UV radiations, protecting the iodide electrolyte from thermal degradation. To further study the performance of the down-shifting layer in DSSC, the Ce3+:SrF2/TiO2 nanocomposite-based photoanodes were used to fabricate the DSSCs. As a result, the nanocomposite-based device has demonstrated an excellent photo-conversion efficiency of 8.8%. The improvement in the incident-photon-to-current efficiency curve and electrochemical values (J(sc) = 15.2 mA cm(-2), V-oc = 0.82 V, and FF = 0.73) are due to the enhanced visible-light photon harvesting and high chemical stability.

The high trap-state density and low conductivity in compact TiO2 (c-TiO2) layer limits the power conversion efficiency (PCE) of organic-inorganic hybrid perovskite solar cells (HPSCs). Metal doping in c-TiO2 has been proven to be a successful strategy for enhancing the PCE of HPSCs. Herein, Zr is incorporated in the c-TiO2 layer with different doping concentrations, and its impact on the photovoltaic performance of methylammonium lead iodide (MAPbI(3)) HPSCs is investigated. Inclusion of Zr enhances the charge carrier collection at TiO2/perovskite junction as well as conductivity of TiO2 layer. It is demonstrated that Zr-doping reduces the dark current significantly by suppressing non-geminated recombinations, leakage path, and electron trap-states. As a result, the HPSCs with optimum Zr-doping (10 vol%) exhibits open-circuit voltage (V-OC) of 1.076 V, short-circuit current density (J(SC)) of 23.57 mA cm(-2), and PCE of 18.16% under one-sun illumination conditions. UV absorption confirms the increase in bandgap upon Zr-doping that leads to favorable band alignment with the perovskite layer. Further, the engineered solar cells are probed for current density-voltage (J-V) hysteresis, operational stability, leakage current, intensity-dependence behavior, and electrochemical impedance spectroscopy (EIS).

Herein, phase pure and highly crystalline Ce:LuAG nano-ceramics were fabricated using a novel, ultra-fast microwave sintering approach. The influence of microwave sintering on the microstructural, photoluminescence, and dielectric characteristics of Ce:LuAG nano-ceramic powders was examined. Microwave-assisted sintering of Ce:LuAG nano-ceramic powders yielded high crystallinity, low lattice strain, and reduced grain size. The process also improved the sintering kinetics and enhanced the surface diffusion between the grains, resulting in enhanced luminescence and dielectric properties. The Cole-Cole impedance plots showed single semicircular arcs, indicating non-Debye relaxation and a high dielectric constant in the microwave-sintered Ce:LuAG nano-ceramic and highlighting its potential for use in optoelectronics.

This work presents a detailed microstructure-property correlation of high power diode laser nitrided titanium based on its dendrite and martensite microstructures, structural phase and microhardness. For the laser nitrided titanium, cooling rate was estimated for the first time using empirical power law relationship by considering the martensite width and dendrite arm spacings and the results were validated by analytical thermal model. A processing window was formulated for laser gas nitriding of titanium by relating the experimental parameters such as laser processing parameters, nitrogen gas pressure and titanium nitride phases. The novelty of this work is demonstration of laser nitriding of titanium in laminar flow nitrogen gas environment using a simple acrylic container setup that avoids design and fabrication of a complex gas nozzle delivery system. In this setup, a thin transparent acrylic sheet was used as optical window instead of expensive quartz glass, to transmit high power diode laser beam at 980 nm wavelength to irradiate the substrate work piece in a closed container. This simple laser nitriding technique has created characteristic golden colored TiN surface with high surface hardness. Dendrite and martensite microstructures of the laser nitrided titanium were analyzed by optical and FESEM microscopy. EDAX analysis revealed the presence of nitrogen in laser nitrided titanium and X-ray diffraction confirmed the TiN phases. The microhardness of laser nitrided titanium is six times higher than its substrate.

The present report explores third order nonlinear optical behavior of phase pure Yb3+:YAG nanoparticles for the first time by Z-scan technique. The measurement was carried out using diode pumped continuous wave (CW) Nd:YAG laser at 532 nm. The Yb:YAG nanoparticles exhibit characteristic near-infrared (NIR) emission at 1030 nm under 940 nm excitation. The nanoparticles exhibit high nonlinear refractive index (n(2) = 8.649 x 10(-8) cm(2)/W) and low nonlinear absorption coefficient (beta= 0.109 x 10(-4 )cm/W) giving an appreciable figure of merit (FOM) of similar to 74.50. The excitation power (8.2-10.5W cm(-2 )) dependent emission spectra were recorded to study exchange energy interaction of Yb3+ ions with YAG host lattice. By utilizing the nonlinear refractive index 'n(2)' from Z-scan measurement, thermo-optic coefficient (dn/dt) was calculated to demonstrate Yb3+ :YAG nanomaterial for high power compact solid state laser gain amplifier systems.

Silver nanoparticle was synthesized using D-glucosamine chitosan base as green reducing agent at elevated temperature in alkaline pH ranges. The excess of D-glucosamine chitosan base was used as it is both stabilizing and reducing agent at different pHs, regulates the shape and size of the silver nanoparticles. The progressive growth of silver nanoparticles was monitored by UV-Visible spectral studies. A sharp peak at 420 nm indicates the formation of spherical silver nanoparticles. The size and shape of silver nanoparticles were observed from Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) methods. The anisotropically grown nanoparticles were used as probe for Surface Enhanced Raman Studies (SERS) using ATP (4-aminothiophenol) as a model system. The catalytic behavior of silver nanoparticles was exploited for 4-nitrophenol reduction and observed that the reduction reaction follows pseudo first order kinetics with a rate constant 0.65 min. The antibacterial activity of silver nanoparticles was also tested for both gram-positive and-negative microorganisms, in which higher zone of inhibition was observed for gram negative microorganism. (C) 2019 Published by Elsevier B.V.

Surface encapsulation of nanophosphors by nanoscale silica (SiO2) coating is an effective strategy to enhance the luminescence property for opto-electronic application. The present work investigates about the synthesis of silica encapsulated LuAG:Pr3+ nanocrystals by surfactant assisted co-precipitation and rapid microwave calcination. The ultrafast microwave heating of silica encapsulated LuAG:Pr at 1050 degrees C for 10 min resulted in the formation of well-crystallized nanocrystals in cubic phase that evidenced by XRD Rietveld analysis. FE-SEM and HR-TEM examinations revealed the formation of similar to 6 nm nanoscale silica film encapsulation on LuAG:Pr nanocrystals. EDS elemental and XPS investigations confirmed the presence of SiO2 layer encapsulation on the surface of nanoparticle. The nanoscale silica encapsulated LuAG:Pr nanocrystals displayed two-fold enhancement in luminescence red emission than uncoated counterpart nanocrystals. The continuous nanoscale silica coating served as an integrating sphere that confides incident photons by means of multiple reflections and improved the light extraction. Temperature dependent photoluminescence analysis of the silica coated LuAG:Pr3+ nanocrystal was also studied. It revealed the original emission intensity was stable up to 425 K and start decreasing to 55% at 520 K, which promoted stable high temperature luminescence behavior. Thermoluminescence investigation was also performed for uncoated and silica-coated LuAG:Pr nanocrystals by irradiated them with high energy gamma-ray (Co-60) source at 200 Gy for 2 min. The trap-depth in terms of activation energy (E) and frequency factor (s) of the gamma ray irradiated nanoparticles was estimated by computerized GCD operation.

SrF2 based upconversion nanoparticles (UCNPs) were synthesized by hydrothermal method using ethylenediaminetetraacetic acid (EDTA) as surfactant, by doping with single-lanthanide-activator Er ion and sensitizer-activator Yb3+−Er3+ ion-pair. The excited state absorption (ESA) and energy transfer upconversion (ETU) properties were investigated respectively by synthesizing SrF2:2%Er and SrF2:20%Yb,2%Er nanoparticles. EDTA aided hydrothermal synthesis resulted in nano-rod, nano-plate and nano-sphere morphological particles. The hydrothermally grown SrF2:Yb,Er UCNPs are formed as nano-spheres in size ~ 30 to 60 nm. It gives a high specific surface area of 47.17 to 23.58 m2 g−1. The nano-spherical SrF2:Yb,Er resulted an intense red upconversion emission at 660 nm, under the near-infrared (NIR) 980 nm excitation, due to its high specific surface area and ETU mechanism. The post-calcined SrF2:Yb3+,Er3+ gives better red-to-green emission intensity ratio compared to the as-prepared counterparts. SrF2:Er3+ gives very weak red emission due to ESA mechanism. The optical energy gap of SrF2:Yb,Er UCNP was calculated using the barycentre of green emission at 524 and 542 nm from the thermally coupled energy levels of 2H11/2 and 4S3/2. It gives an optical energy gap of 766 cm−1 and the estimated thermal sensitivity is 1.22% K−1 at 300 K. The result is in agreement with other published reports. We also demonstrated the NIR-to-NIR (980-to-850 nm) upconversion emission in the SrF2:Yb3+, Er3+ nanoparticle.

A novel synthesis approach is proposed to prepare strong NIR emitting Yb3+ doped YAG (Yb:YAG) nanoparticles at different Yb3+ concentrations by a modified refluxer assisted homogeneous precipitation using dual polymeric surfactant functionalization approach. Ultrafast microwave calcination has achieved Yb:YAG nanoparticles in pseudo-spherical morphology under the influence of polymeric dual SDS-PEG surfactants, evidenced from HR-TEM observation. XRD pattern of Yb:YA(G) nanoparticles calcined at 900 degrees C resulted in cubic phase formation without the evolution of YAlO3 and Y3AlO4 intermediate phases. XPS analysis revealed the presence of Yb3+ and Yb2+ mixed valence states in high-Yb doped YAG, whereas only Yb3+ is seen in moderately-Yb doped YAG nanoparticles. UV-Visible diffuse reflectance spectrum exhibit characteristic optical absorption at 940 nm is attributed to F-2(7/2) -> F-2(5/2) electronic transitions of Yb3+ ions. From these spectral data, optical parameters such as Stark energy splitting (Delta E), absorption coefficient (alpha), refractive index (n) and absorption cross section (sigma(abs)) are estimated. Photoluminescence spectra of moderately (5 at%) doped Yb:YAG nanoparticles showed strong near infrared emission at 1030 nm due to Yb3+ ions that confirmed by XPS analysis. Also, the stimulated emission cross section (sigma(em)) is calculated using Fuchtbauer-Ladenburg equation. The fluorescence decay lifetime result also implies that the moderately doped YY-5S sample exhibits higher decay lifetime of 2.08 ms. In addition, present work explores the thermally stimulated luminescence properties of Yb:YAG nanoparticles for the first time by high energy gamma-ray irradiation at different dose rates. TSL kinetic parameters such as structural factor (mu(g)), order of kinetics (b), trap depth in terms of activation energy (E) and frequency factor (s) are estimated.