Interfacial Design of Particulate Photocatalyst Materials for Green Hydrogen Production

Green hydrogen production using particulate photocatalyst materials has attracted much attention in recent years because this process could potentially lead to inexpensive and scalable solar-to-chemical energy conversion systems. Although the development of efficient particulate photocatalysts enabling one-step overall water splitting (OWS) with solar-to-hydrogen efficiencies in excess of 10 % remains challenging, promising photocatalyst candidates exhibiting OWS activity have been demonstrated. This review provides a comprehensive introduction to the solar-to-hydrogen energy conversion process of semiconductor photocatalyst materials and highlights recent advances in photocatalytic OWS via both one-step and two-step photoexcitation processes. The review also covers recent developments in the photocatalytic OWS of SrTiO3, including the establishment of large-scale photocatalytic systems, interfacial design using cocatalysts to enhance water splitting activity, and its photoelectrochemical (PEC) properties at the electrified solid/liquid interface. In addition, there is a special focus on visible-light-absorbing oxynitride and oxysulfide particulate photocatalysts with absorption edges near 600 nm. Methods for photocatalyst preparation and surface modification, as well as PEC properties, are also discussed. The semiconductor properties of particulate photocatalysts obtained from photoelectroanalytical evaluations using particulate photoelectrodes are evaluated. This review is intended to provide guidelines for the future development of particulate photocatalysts capable of efficient and stable OWS.Citation: Higashi T, Domen K. Interfacial Design of Particulate Photocatalyst Materials for Green Hydrogen Production. ChemSusChem. 2024 Nov 11;17(21):e202400663. doi: 10.1002/cssc.202400663. Epub 2024 Jul 8. PMID: 38794839

Selective chromium dissolution as an interfacial design strategy for enhanced oxygen evolution activity in CrFeCoNi oxy-carbide films

High-entropy compounds have demonstrated remarkable electrocatalytic activity for oxygen evolution reaction (OER) in water. In this study, amorphous FeNi, CrFeNi, and CrFeCoNi oxy-carbide films were prepared using a single-step electrodeposition technique in an aqueous medium. Among them, CrFeCoNi films displayed outstanding electrocatalytic OER performance, achieving an overpotential of 315 mV at a current density (J) of 10 mA cm−2. At J of 50 mA cm−2, selective dissolution of Cr-species within CrFeCoNi was observed, which enhanced both electrocatalytic activity and stability of the film. This oxidative Cr dissolution process not only expanded the electrochemically active surface area but also facilitated the reoxidation of Fe, Co, and Ni, thereby weakening the binding strength of intermediates at catalytic sites. In addition, selective Cr dissolution improved the conductivity of the films owing to newly formed metal–metal bonding, promoting electron transfer and improving the OER performance, achieving an overpotential of 264 mV at J of 10 mA cm−2. This single-step electrodeposition approach and selective dissolution mechanism provide an effective pathway for the design and development of high-entropy compound-based electrocatalysts for efficient water electrolysis

Toward the Analysis of Office Workers’ Mental Indicators Based on Wearable, Work Activity, and Weather Data

In recent years, many organizations have prioritized efforts to detect and treat mental health issues. In particular, office workers are affected by many stressors, and physical and mental exhaustion, which is also a social problem. To improve the psychological situation in the workplace, we need to clarify the cause. In this paper, we conducted a 14-day experiment to collect wristband sensor data as well as behavioral and psychological questionnaire data from about 100 office workers. We developed machine learning models to predict psychological indexes using the data. In addition, we analyzed the correlation between behavior (work content and work environment) and psychological state of office workers to reveal the relationship between their work content, work environment, and behavior. As a result, we showed that multiple psychological indicators of office workers can be predicted with more than 80% accuracy using wearable sensors, behavioral data, and weather data. Furthermore, we found that in the working environment, the time spent in “web conferencing”, “working at home (living room)”, and “break time (work time)’ had a significant effect on the psychological state of office workers.3rd International Conference on Activity and Behavior Computing, ABC 2021, 22 October 2021 through 23 October 2021, Onlinejournal articl

Estimating the quasi-Fermi level of holes at the surface of semiconductor photoanodes using outer-sphere redox couples

Semiconductor electrodes can catalyze photo-induced redox reactions with light illumination. Photoexcitation produces excited carriers that subsequently transfer to the front and back contacts as determined by the bulk and surface properties of the photoelectrodes. This transfer defines the resultant quasi-Fermi levels of the photo-generated carriers at the photoelectrode surface, which, in turn, impacts the efficiency of surface photoelectrochemical reactions. However, determining such quasi-Fermi levels is not a simple task. In this study, we introduce a method for estimating the quasi-Fermi level of holes using outer-sphere electron transfer reactions. The quasi-Fermi level of holes is estimated by linking the oxidation photocurrent on photoanodes to the separately measured electrode potential on a stable metal electrode. Using this method, the quasi-Fermi level of holes at the surface is monitored in response to variations in applied potential and light intensity. This approach effectively separates the photocurrents of the CdS model electrode between surface redox reaction and photocorrosion, while concurrently quantifying the dynamic quasi-Fermi level at the surface. This work facilitates quantitative understanding of photoelectrochemical reactions on semiconductor electrodes to design green chemical transformation systems

Production of Prompt Charmonia in e+e- Annihilation at sqrt[s] ≈ 10.6 GeV

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Photoelectrochemical properties of p-type CuBi2O4 prepared by spray pyrolysis

Solar-to-chemical energy conversion using semiconductor-based photoelectrodes for photoelectrochemical water splitting is a promising technology contributing to an environmentally friendly society. CuBi2O4 is a p-type semiconductor material that can be used in visible-light-responsive photocathodes. The fabrication of CuBi2O4 has been examined using wet processes such as spray pyrolysis of precursor solutions containing organic solvents and organic additives. Spray pyrolysis causes problems such as CO2 emission during the decomposition of the precursor solution. In this study, we established a carbon-free method for the fabrication of CuBi2O4 using a precursor solution comprising Cu(NO3)2 and Bi(NO3)3 dissolved in a diluted nitric acid aqueous solution. The impact of surface modification with Pt cocatalyst for hydrogen evolution reaction was investigated. This study provides rational guidelines for visible-light-absorbing photoelectrodes utilizing a carbon-free preparation process.departmental bulletin pape