Continuous Flow Photoelectrochemical Reactor with Gas Permeable Photocathode: Enhanced Photocurrent and Partial Current Density for CO Reduction.

Photoelectrochemical (PEC) CO reduction using a photocathode is an attractive method for making valuable chemical products due to its simplicity and lower overpotential requirements. However, previous PEC processes have often been diffusion-limited leading to low production rates of the CO reduction reaction, due to inefficient gas diffusion through the liquid electrolyte to the catalyst surface, particularly at high current densities. In this study, a gas-permeable photocathode in a continuous flow PEC reactor is incorporated, which facilitates the direct supply of CO gas to the photocathode-electrolyte interface, unlike dark reaction-based flow reactors.

Effect of Feature Shape and Dimension of a Confinement Geometry on Selectivity of Electrocatalytic CO Reduction.

The local confinement effect, which can generate a high concentration of hydroxide ions and reaction intermediates near the catalyst surface, is an important strategy for converting CO into multi-carbon products in electrocatalytic CO reduction. Therefore, understanding how the shape and dimension of the confinement geometry affect the product selectivity is crucial. In this study, we report for the first time the effect of the shape (degree of confinement) and dimension of the confined space on the product selectivity without changing the intrinsic property of Cu.

Retarding Ion Migration for Stable Blade-Coated Inverted Perovskite Solar Cells.

The fabrication of perovskite solar cells (PSCs) through blade coating is seen as one of the most viable paths toward commercialization. However, relative to the less scalable spin coating method, the blade coating process often results in more defective perovskite films with lower grain uniformity. Ion migration, facilitated by those elevated defect levels, is one of the main triggers of phase segregation and device instability.

Atomic-Scale Homogeneous RuCu Alloy Nanoparticles for Highly Efficient Electrocatalytic Nitrogen Reduction.

Ruthenium (Ru) is the most widely used metal as an electrocatalyst for nitrogen (N ) reduction reaction (NRR) because of the relatively high N adsorption strength for successive reaction. Recently, it has been well reported that the homogeneous Ru-based metal alloys such as RuRh, RuPt, and RuCo significantly enhance the selectivity and formation rate of ammonia (NH ). However, the metal combinations for NRR have been limited to several miscible combinations of metals with Ru, although various immiscible combinations have immense potential to show high NRR performance.

Generation of high-density nanoparticles in the carbothermal shock method.

The carbothermal shock (CTS) method has attracted considerable attention in recent years because it enables the generation of finely controlled polyelemental alloy nanoparticles (NPs). However, fabricating high surface coverage of NPs with minimized exposure of the carbon substrate is essential for various electrochemical applications and has been a critical limitation in CTS method. Here, we developed a methodology for creating NPs with high surface coverage on a carbon substrate by maximizing defect sites of cellulose during CTS.

Synergistic Effect of Cu O Mesh Pattern on High-Facet Cu Surface for Selective CO Electroreduction to Ethanol.

Although the electroconversion of carbon dioxide (CO ) into ethanol is considered to be one of the most promising ways of using CO , the ethanol selectivity is less than 50% because of difficulties in designing an optimal catalyst that arise from the complicated pathways for the electroreduction of CO to ethanol. Several approaches including the fabrication of oxide-derived structures, atomic surface control, and the Cu /Cu interfaces have been primarily used to produce ethanol from CO . Here, a combined structure with Cu and high-facets as electrocatalysts is constructed by creating high-facets of wrinkled Cu surrounded by Cu O mesh patterns.

Nanoscale Wrinkled Cu as a Current Collector for High-Loading Graphite Anode in Solid-State Lithium Batteries.

Solid-state lithium batteries have been intensively studied as part of research activities to develop energy storage systems with high safety and stability characteristics. Despite the advantages of solid-state lithium batteries, their application is currently limited by poor reversible capacity arising from their high resistance. In this study, we significantly improve the reversible capacity of solid-state lithium batteries by lowering the resistance through the introduction of a graphene and wrinkle structure on the surface of the copper (Cu) current collector.

Interface Matters: Enhanced Photoluminescence and Long-Term Stability of Zero-Dimensional Cesium Lead Bromide Nanocrystals Gas-Phase Aluminum Oxide Encapsulation.

Cesium lead halide perovskite nanocrystals (PNCs), while possessing facile chemical synthesis routes and high photoluminescence (PL) properties, are still challenged by issues of instability and degradation. Although atomic layer deposition (ALD) of metal oxides has been one of the common encapsulation approaches for longer term stability, its application inevitably resulted in severe loss of emission efficiency and at times partial loss of structural integrity of perovskites, creating a bottleneck in its practical viability. We demonstrate a nondestructive modified gas-phase technique with codeposition of both precursors trimethylaluminum and water to dramatically enhance the PL emission in zero-dimensional (0D) CsPbBr PNCs alumina encapsulation.

Dynamical Interconversion between Excitons and Geminate Charge Pairs in Two-Dimensional Perovskite Layers Described by the Onsager-Braun Model.

Time-resolved photoluminescence (PL) and femtosecond transient absorption (TA) spectroscopy are employed to study the photoexcitation dynamics in a highly emissive two-dimensional perovskite compound (en)PbBr·3Br with the ethylene diammonium (en) spacer. We find that while the PL kinetics is substantially -dependent over the whole range of studied temperatures ∼ 77-350 K, the PL quantum yield remains remarkably nearly -independent up to ∼ 280-290 K, appreciably decreasing only at higher temperatures. Considerable differences are also revealed between the TA spectra and the responses to the excitation power at low and at room temperatures.

Delayed Photoluminescence and Modified Blinking Statistics in Alumina-Encapsulated Zero-Dimensional Inorganic Perovskite Nanocrystals.

We demonstrate enhancement of the photoluminescence (PL) properties of individual zero-dimensional (0D) CsPbBr perovskite nanocrystals (PNCs) upon encapsulation by alumina using an appropriately modified atomic layer deposition method. In addition to the increased PL intensity and improved long-term stability of encapsulated PNCs, our single-particle studies reveal substantial changes in the PL blinking statistics and the persistent appearance of the long-lived, "delayed" PL components. The blinking patterns exhibit a modification from the fast switching between fluorescent ON and OFF states found in bare PNCs to a behavior with longer ON states and more isolated OFF states in alumina-encapsulated PNCs.

Understanding effects of precursor solution aging in triple cation lead perovskite.

The solution process is the most widely used method to prepare perovskite absorbers for high performance solar cells due to its ease for fabrication and low capital cost. However, an insufficient level of reproducibility of the solution process is often a concern. Complex precursor solution chemistry is likely one of the main reasons for the reproducibility issue.

Improving Uniformity and Reproducibility of Hybrid Perovskite Solar Cells via a Low-Temperature Vacuum Deposition Process for NiO Hole Transport Layers.

Recently, the trend in inverted hybrid perovskite solar cells (PVSCs) has been to utilize NiO as hole transport layers. However, the majority of reported solution-processed NiO films require a high-temperature thermal annealing process, which is unfavorable for large-scale manufacturing and suffers from lack of uniformity. We report, for the first time, e-beam evaporation as a low-temperature vacuum process for the deposition of NiO hole transport layers for PVSCs.

Ultralong Radiative States in Hybrid Perovskite Crystals: Compositions for Submillimeter Diffusion Lengths.

Organic-inorganic hybrid perovskite materials have recently evolved into the leading candidate solution-processed semiconductor for solar cells due to their combination of desirable optical and charge transport properties. Chief among these properties is the long carrier diffusion length, which is essential to optimizing the device architecture and performance. Herein, we used time-resolved photoluminescence (at low excitation fluence, 10.

CsPb Br Single Crystals: Synthesis and Characterization.

CsPb Br is a ternary halogen-plumbate material with close characteristics to the well-reported halide perovskites. Owing to its unconventional two-dimensional structure, CsPb Br is being looked at broadly for potential applications in optoelectronics. CsPb Br investigations are currently limited to nanostructures and powder forms of the material, which present unclear and conflicting optical properties.

Highly transparent and UV-resistant superhydrophobic SiO(2)-coated ZnO nanorod arrays.

Highly transparent and UV-resistant superhydrophobic arrays of SiO2-coated ZnO nanorods are prepared in a sequence of low-temperature (<150 °C) steps on both glass and thin sheets of PET (2 × 2 in.(2)), and the superhydrophobic nanocomposite is shown to have minimal impact on solar cell device performance under AM1.5G illumination.

Demonstration of the feasibility of a complete ellipsometric characterization method based on an artificial neural network.

Ellipsometry is an optical technique that is widely used for determining optical and geometrical properties of optical thin films. These properties are in general extracted from the ellipsometric measurement by solving an inverse problem. Classical methods like the Levenberg-Marquardt algorithm are generally too long, depending on direct calculation and are very sensitive to local minima.

Recognition of diffraction-grating profile using a neural network classifier in optical scatterometry.

Optical scatterometry has been given much credit during the past few years in the semiconductor industry. The geometry of an optical diffracted structure is deduced from the scattered intensity by solving an inverse problem. This step always requires a previously defined geometrical model.