Low-temperature ionic layer adsorption and reaction grown anatase TiO 2 nanocrystalline films for efficient perovskite solar cell and gas sensor applications

A low-temperature (90 °C) and directly grown anatase titanium dioxide (TiO2) nanocrystalline film using successive ionic layer adsorption and reaction (SILAR) for perovskite solar cell and gas sensor applications. TiO2 nanocrystalline electron transfer layer (ETL) improves the power conversion efficiency (PCE) of perovskite solar cells due to faster charge transport kinetics as well as slower charge recombination process. The optimized TiO2 nanocrystalline ETL (15 L) demonstrates as high as ~10% PCE with a short circuit current density of 18.0 mA/cm2, open circuit voltage of 0.81 V and fill factor of 66.3% in perovskite solar cells. Furthermore, room-temperature ammonia sensing characteristics of TiO2 nanocrystalline film (25 L) were  demonstrated for various concentration levels of ammonia in dry air conditions. A high room-temperature response of 80% was achieved at 100 ppm of ammonia with rapid response and recovery signatures of 30 and 85 s, and nearly fifteen days stability, respectively. The response of the sensor to other gases such as formaldehyde, petrol, ethanol acetone, and ammonia etc, indicated a high selectivity towards volatile organic compounds of ammonia gas. The room temperature operation, with high selectivity, repeatability and fast transition times, suggests potentially useful in flexible and cost-effective production in optoelectrochemical device technology

Natural carbonized sugar as a low-temperature ammonia sensor material: experimental, theoretical and computational studies

Carbonized sugar (CS) has been synthesized via microwave-assisted carbonization of market-quality tabletop sugar bearing in mind the advantages of this synthesis method, such as being useful, cost-effective, and eco-friendly. The as-prepared CS has been characterized for its morphology, phase purity, type of porosity, pore-size distribution, and so on. The gas-sensing properties of CS for various oxidizing and reducing gases are demonstrated at ambient temperature, where we observe good selectivity toward liquid ammonia among other gases. The highest ammonia response (50%) of a CS-based sensor was noted at 80 °C for 100 ppm concentration. The response and recovery times of the CS sensor are 180 and 216 s, respectively. This unveiling ammonia-sensing study is explored through a plausible theoretical mechanism, which is further well-supported by computational modeling performed using density function theory. The effect of relative humidity on the CS sensor has also been studied at ambient temperature, which demonstrated that the minimum and maximum (20–100%) relative humidity values revealed 16 and 62% response, respectively

Gold sensitized sprayed SnO2 nanostructured film for enhanced LPG sensing

We report LPG sensing of gold (Au)-sensitized SnO2 nanostructured film fabricated by an easy spray pyrolysis deposition method whose surface morphology is confirmed by field-emission scanning electron microscopy and atomic force microscopy images and structure by X-ray diffraction pattern. Energy dispersive X-ray spectrometer analysis has carried out for finding elemental composition. The SnO2 film is uniform and consists of spherical particles of ∼10nm. The highest gas response observed at 780ppm LPG concentration for pristine SnO2 is 28%, at operating temperature 623K, which is greatly improved on Au sensitization up to 57% with 60s rapid response time at 598K operating temperature. The high gas response is due to electronic effect and catalytic spill-over effect of Au sensitization. The improved sensing mechanism has throughly been explored

Metal-free heterogeneous and mesoporous biogenic graphene-oxide nanoparticle-catalyzed synthesis of bioactive benzylpyrazolyl coumarin derivatives

We report the preparation of graphene oxide nanoparticles (GONPs), a metal-free, heterogeneous, non-toxic, reusable and mesoporous green-(acid)-catalyst obtained by sugar carbonization through a micro-wave chemical synthesis method for the synthesis of bio-active benzylpyrazolyl coumarin derivatives (BCDs) under thermal conditions (50 [degree]C) in ethanol solvent. The obtained products were purified by re-crystallization from ethanol, assuring usability of GONPs in multicomponent reactions (MCRs) that could find wide application in the synthesis of a variety of biologically potent molecules of therapeutic significance

Determining the Effect of Cation (Ti/Zr) Doping in Bismuth Oxide for Electrochemical CO2 Reduction to Formic Acid: A DFT Study

First-principles-based density functional theory (DFT)calculationswere used to explore the electrochemical CO2 reduction(ECR) activity of cation-doped Bi2O3. We studiedthe ECR reaction over pure and doped Bi2O3 (100)surfaces and demonstrated Gibbs free energy diagrams of HCOOH formationvia COOH and HCOO pathways. Compared with pure bismuth oxide, dopingcan alter the rate-determining step and reduce the Gibbs free energyfrom 2.98 to 0.11 eV. The CO2 reduction activity was foundto be most productive on the TiZr-Bi2O3 surface with onset potentials of -0.23 and 0.55 V via theCOOH and HCOO pathways, respectively. The probability of CO formationthrough the ECR reaction was also investigated using Gibbs free energycalculations, and it was found that Bi2O3, Ti-Bi2O3, Zr-Bi2O3, andTiZr-Bi2O3 displayed insufficient ECRactivity to produce CO. We also compared the selectivity of the ECRreaction and the hydrogen evolution reaction (HER) to demonstratethe practicality of the electrocatalysts

Predicting photoresist sensitivity using machine learning

We introduce a scheme for predicting photoresist sensitivity using machine learning (ML) work flow on the basis of previously reported experimental data. Different ML models, specifically Linear Regression, Kernel Ridge Regression, Gaussian Process Regressor, Random Forest Regressor, and Multilayer Perceptron Regressor, were evaluated to rapidly identify the best sensitivity prediction model. The experiment was carried out on the Google Colab platform using the Materials Simulation Toolkit for Machine Learning and Sci-kit Learn. Different ensemble models were utilized without splitting the dataset to determine the prediction accuracy of the ML models. The hyperparameter optimization was established with a 70/30 ratio, followed by a K-Fold cross-validation to improve the model prediction performance. The optimized ML model showed a prediction performance of R-2 = 0.83, RMSE = 10.53, and MARE = 0.68. Hence, by optimizing the hyperparameters used in the ML model, the sensitivity of the photoresist materials can be predicted with improved prediction performance

DFT-study supported synergistic electrochemical supercapacitor performance of Bi2MoS6 nanosheets

Synergistic electrochemical performance of the bismuth molybdenum sulphide (Bi2MoS6, BMS) nanosheets can be beneficial for fast ion exchange kinetics in electrolyte solution for energy storage performance. Bismuth sulphide (Bi2S3, BS), molybdenum sulphide (MoS2, MS), and BMS electrode materials of different morphologies are grown on stainless-steel (SS) conducting substrate using a wet chemical process. A 0 - 1 V operating potential window vs. Ag/AgCl has been utilized for half-cell analysis wherein, 947.4 F g- 1 specific capacitance is obtained for BMS nanosheet-like electrode at 0.6 Ag-1 current density with nearly 97 % stability which is better than BS and MS electrode materials. Full understanding of synergistic effect i.e., enhancement of electrochemical properties, has clearly been revealed by applying ab-initio theoretical calculations using density functional theory. The values of power density and energy density of the as-constructed symmetric supercapacitor device by using BMS electrode are respectively found to be 1130 Wkg- 1 and 85 Whkg- 1. A panel of forty-two LEDs coupled in series has been powered through symmetric device to demonstrating the practical application of the asprepared nanosheet-type BMS electrode material for commercial feasibility

Bismuth oxide-doped graphene-oxide nanocomposite electrode for energy storage application

Nanocrystalline and porous bismuth oxide-doped graphene oxide nanocomposite (Bi2O3-GO NC) electrode material synthesized via microwave irradiation method has been envisaged for supercapacitor application. Surface morphology, elemental configuration, phase purity, surface area, porosity, and binding energy etc., are initially screened and then preferred in electrochemical measurement analysis. The as-obtained Bi2O3-GO NC electrode adduces a better performance with quasi-faradaic redox reactions in electrochemical measurements over pristine GO in 6 M KOH electrolyte solution. The specific capacitance of the Bi2O3-GO NC electrode measured at current densities 5-14 A/g is varied from 1250 to 933 F/g. The as-assembled Bi2O3-GO//Bi2O3-GO symmetric supercapacitor device reveals an exceptional electrochemical performance with 25.83 W-h/kg specific energy at 337 W/kg specific power, and excellent stability of about 80% for 5000 cycles, evidencing usability potential of meta

Hydrogen Evolution Reaction Activities of Room-Temperature Self-Grown Glycerol-Assisted Nickel Chloride Nanostructures

Three-dimensional nanomaterials of desired structural/morphological properties and highly porous with a high specific surface area are important in a variety of applications. In this work, glycerol-mediated self-growth of 3-D dandelion flower-like nickel chloride (NiCl2) from nickel-foam (NiF) is obtained for the first time using a room-temperature (27 °C) processed wet chemical method for electrocatalysis application. Glycerol-mediated self-grown NiCl2 flowers demonstrate an excellent electrocatalytic performance towards the hydrogen evolution reaction (HER), which is much superior to the NiF (303 mV) and NiCl2 electrode prepared without glycerol (208 mV) in the same electrolyte solution. With a Tafel slope of 41 mV dec−1, the NiCl2 flower electrode confirms improved reaction kinetics as compared to the other two electrodes, i.e., NiF (106 mVdec−1) and NiCl2 obtained without glycerol (56 mV dec−1). The stability of the glycerol-based NiCl2 electrode has further been carried out for 2000 cycles with the overpotential diminution of just 8 mV, approving an electrocatalyst potential of glycerol-based NiCl2 electrode towards HER kinetics. This simple and easy growth process involves nucleation, aggregation, and crystal growth steps for producing NiCl2 nanostructures for electrocatalytic water splitting application through the HER process

Gold sensitized sprayed SnO2 nanostructured film for enhanced LPG sensing

We report LPG sensing of gold (Au)-sensitized SnO2 nanostructured film fabricated by an easy spray pyrolysis deposition method whose surface morphology is confirmed by field-emission scanning electron microscopy and atomic force microscopy images and structure by X-ray diffraction pattern. Energy dispersive X-ray spectrometer analysis has carried out for finding elemental composition. The SnO2 film is uniform and consists of spherical particles of ∼10nm. The highest gas response observed at 780ppm LPG concentration for pristine SnO2 is 28%, at operating temperature 623K, which is greatly improved on Au sensitization up to 57% with 60s rapid response time at 598K operating temperature. The high gas response is due to electronic effect and catalytic spill-over effect of Au sensitization. The improved sensing mechanism has throughly been explored