Charge Transfer Kinetics in Halide Perovskites: On the Constraints of Time-Resolved Spectroscopy Measurements.

Understanding photophysical processes in lead halide perovskites is an important aspect of optimizing the performance of optoelectronic devices. The determination of exact charge carrier extraction rate constants remains elusive, as there is a large and persistent discrepancy in the reported absolute values. In this review, we concentrate on experimental procedures adopted in the literature to obtain kinetic estimates of charge transfer processes and limitations imposed by the spectroscopy technique employed.

Stable Operation of Paired CO Reduction/Glycerol Oxidation at High Current Density.

Despite the considerable efforts made by the community, the high operation cell voltage of CO electrolyzers is still to be decreased to move toward commercialization. This is mostly due to the high energy need of the oxygen evolution reaction (OER), which is the most often used anodic pair for CO reduction. In this study, OER was replaced by the electrocatalytic oxidation of glycerol using carbon-supported Pt nanoparticles as an anode catalyst.

Au-decorated SbSe photocathodes for solar-driven CO reduction.

Photoelectrodes with FTO/Au/SbSe/TiO/Au architecture were studied in photoelectrochemical CO reduction reaction (PEC CORR). The preparation is based on a simple spin coating technique, where nanorod-like structures were obtained for SbSe, as confirmed by SEM images. A thin conformal layer of TiO was coated on the SbSe nanorods ALD, which acted as both an electron transfer layer and a protective coating.

Effect of Single-Crystal TiO/Perovskite Band Alignment on the Kinetics of Electron Extraction.

The kinetics of electron extraction at the electron transfer layer/perovskite interface strongly affects the efficiency of a perovskite solar cell. By combining transient absorption and time-resolved photoluminescence spectroscopy, the electron extraction process between FACsPb(IBr) and TiO single crystals with different orientations of (100), (110), and (111) were probed from subpicosecond to several hundred nanoseconds. It was revealed that the band alignment between the constituents influenced the relative electron extraction process.

Renewable Syngas Generation via Low-Temperature Electrolysis: Opportunities and Challenges.

The production of syngas (i.e., a mixture of CO and H) via the electrochemical reduction of CO and water can contribute to the green transition of various industrial sectors.

One-step electrodeposition of binder-containing Cu nanocube catalyst layers for carbon dioxide reduction.

To reach industrially relevant current densities in the electrochemical reduction of carbon dioxide, this process must be performed in continuous-flow electrolyzer cells, applying gas diffusion electrodes. Beyond the chemical composition of the catalyst, both its morphology and the overall structure of the catalyst layer are decisive in terms of reaction rate and product selectivity. We present an electrodeposition method for preparing coherent copper nanocube catalyst layers on hydrophobic carbon paper, hence forming gas diffusion electrodes with high coverage in a single step.

Comparison of TiO and ZnO for Heterogeneous Photocatalytic Activation of the Peroxydisulfate Ion in Trimethoprim Degradation.

The persulfate-based advanced oxidation process is a promising method for degrading organic pollutants. Herein, TiO and ZnO photocatalysts were combined with the peroxydisulfate ion (PDS) to enhance the efficiency. ZnO was significantly more efficient in PDS conversion and SO generation than TiO.

Effects of Iron Species on Low Temperature CO Electrolyzers.

Electrochemical energy conversion devices are considered key in reducing CO emissions and significant efforts are being applied to accelerate device development. Unlike other technologies, low temperature electrolyzers have the ability to directly convert CO into a range of value-added chemicals. To make them commercially viable, however, device efficiency and durability must be increased.

Local hydrophobicity allows high-performance electrochemical carbon monoxide reduction to C products.

While CO can already be produced at industrially relevant current densities CO electrolysis, the selective formation of C products seems challenging. CO electrolysis, in principle, can overcome this barrier, hence forming valuable chemicals from CO in two steps. Here we demonstrate that a mass-produced, commercially available polymeric pore sealer can be used as a catalyst binder, ensuring high rate and selective CO reduction.

Membrane Electrode Assembly for Electrocatalytic CO Reduction: Principle and Application.

Electrocatalytic CO reduction reaction (CO RR) in membrane electrode assembly (MEA) systems is a promising technology. Gaseous CO can be directly transported to the cathode catalyst layer, leading to enhanced reaction rate. Meanwhile, there is no liquid electrolyte between the cathode and the anode, which can help to improve the energy efficiency of the whole system.

Systematic screening of gas diffusion layers for high performance CO electrolysis.

Certain industrially relevant performance metrics of CO electrolyzers have already been approached in recent years. The energy efficiency of CO electrolyzers, however, is yet to be improved, and the reasons behind performance fading must be uncovered. The performance of the electrolyzer cells is strongly affected by their components, among which the gas diffusion electrode is one of the most critical elements.

characterization of continuous flow CO electrolyzers: current status and future prospects.

The performance of continuous-flow CO electrolyzers has substantially increased in recent years, achieving current density and selectivity (particularly for CO production) meeting the industrial targets. Further improvement is, however, necessary in terms of stability and energy efficiency, as well as in high-value multicarbon product formation. Accelerating this process requires deeper understanding of the complex interplay of chemical-physical processes taking place in CO electrolyzer cells.

Development of a Near-Infrared Photoacoustic System for Selective, Fast, and Fully Automatized Detection of Isotopically Labeled Ammonia.

Different environmental and industrial technologies seek for fast and automatic ammonia detection systems, capable of the selective measurement of the concentration of its isotopes at sub-ppm levels, without any interference with the common contaminants. In this work, we report the quasi-simultaneous measurement of NH and NH concentrations based on a near-infrared diode laser-based photoacoustic system. Using a widely tunable external cavity diode laser, four nearby wavelengths within the range of 1531.

CO Conversion on N-Doped Carbon Catalysts via Thermo- and Electrocatalysis: Role of C-NO Moieties.

N-doped carbon (N-C) materials are increasingly popular in different electrochemical and catalytic applications. Due to the structural and stoichiometric diversity of these materials, however, the role of different functional moieties is still controversial. We have synthesized a set of N-C catalysts, with identical morphologies (∼27 nm pore size).

Intermittent Operation of CO Electrolyzers at Industrially Relevant Current Densities.

We demonstrate the dynamic operation of CO electrolyzer cells, with a power input mimicking the output of a solar photovoltaic power plant. The zero-gap design ensured efficient intermittent operation for a week, while avoiding significant performance loss.

Anode Catalysts in CO Electrolysis: Challenges and Untapped Opportunities.

The field of electrochemical carbon dioxide reduction has developed rapidly during recent years. At the same time, the role of the anodic half-reaction has received considerably less attention. In this Perspective, we scrutinize the reports on the best-performing CO electrolyzer cells from the past 5 years, to shed light on the role of the anodic oxygen evolution catalyst.

: Electron-Acceptor-Induced Degradation of CsPbBr Photocathodes.

Lead halide perovskites (LHPs) have emerged as perspective materials for light harvesting, due to their tunable band gap and optoelectronic properties. Photocatalytic and photoelectrochemical (PEC) studies, employing LHP/liquid junctions, are evolving, where sacrificial reagents are often used. In this study, we found that a frequently applied electron scavenger (TCNQ) has dual roles: while it leads to rapid electron transfer from the electrode to TCNQ, enhancing the PEC performance, it also accelerates the decomposition of the CsPbBr photoelectrode.

Impact of Reaction Parameters and Water Matrices on the Removal of Organic Pollutants by TiO/LED and ZnO/LED Heterogeneous Photocatalysis Using 365 and 398 nm Radiation.

In this work, the application of high-power LED and commercial, low-price LED for heterogeneous photocatalysis with TiO and ZnO photocatalysts are studied and compared, focusing on the effect of light intensity, photon energy, quantum yield, electrical energy consumption, and effect of matrices and inorganic components on radical formation. Coumarin (COU) and its hydroxylated product (7-HC) were used to investigate operating parameters on the OH formation rate. In addition to COU, two neonicotinoids, imidacloprid and thiacloprid, were also used to study the effect of various LEDs, matrices, and inorganic ions.

The Mystery of Black TiO: Insights from Combined Surface Science and In Situ Electrochemical Methods.

Titanium dioxide (TiO) is often employed as a light absorber, electron-transporting material and catalyst in different energy and environmental applications. Heat treatment in a hydrogen atmosphere generates black TiO (b-TiO), allowing better absorption of visible light, which placed this material in the forefront of research. At the same time, hydrogen treatment also introduces trap states, and the question of whether these states are beneficial or harmful is rather controversial and depends strongly on the application.

Local Chemical Environment Governs Anode Processes in CO Electrolyzers.

A major goal within the CO electrolysis community is to replace the generally used Ir anode catalyst with a more abundant material, which is stable and active for water oxidation under process conditions. Ni is widely applied in alkaline water electrolysis, and it has been considered as a potential anode catalyst in CO electrolysis. Here we compare the operation of electrolyzer cells with Ir and Ni anodes and demonstrate that, while Ir is stable under process conditions, the degradation of Ni leads to a rapid cell failure.

Visible Light-Generated Antiviral Effect on Plasmonic Ag-TiO-Based Reactive Nanocomposite Thin Film.

The recent coronavirus pandemic pointed out the vulnerability of humanity to new emerging infectious diseases. Experts warn that future pandemics may emerge more frequently with greater devastating effects on population health and the world economy. Although viruses are unable to propagate on lifeless surfaces, they can retain their infectivity and spread further on contact with these surfaces.

Structural Features Dictate the Photoelectrochemical Activities of Two-Dimensional MoSe and WSe Nanostructures.

The exfoliation of layered materials into two-dimensional (2D) semiconductors creates new structural domains, for example, basal planes, defect-rich in-planes, and edge sites. These surface species affect the photoelectrochemical (PEC) performance, which in turn determines their applicability in solar energy conversion technologies. In this study, a custom-designed microdroplet cell-based spatially resolved PEC approach was employed to identify the structural parts and to measure the PEC activity of the mechanically exfoliated MoSe and WSe nanosheets for bulk, few-layer, and monolayer specimens.

Photocorrosion at Irradiated Perovskite/Electrolyte Interfaces.

Metal-halide perovskites transformed optoelectronics research and development during the past decade. They have also gained a foothold in photocatalytic and photoelectrochemical processes recently, but their sensitivity to the most commonly applied solvents and electrolytes together with their susceptibility to photocorrosion hinders such applications. Understanding the elementary steps of photocorrosion of these materials can aid the endeavor of realizing stable devices.