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Heterogeneous photocatalysis: guidelines on experimental setup, catalyst characterization, interpretation, and assessment of reactivity
摘要： Soon after the publication of the first pioneering works on heterogeneous photocatalysis, the number of papers on this topic continuously increased. This intriguing field of research is very complex as it endows with an interdisciplinary overview that involves different aspects of chemistry, physics, material and environmental sciences. Even if photocatalytic applications in real processes are often difficult to be implemented and scaled-up, investigations at laboratory scale are easy to be performed, and in some cases they may give rise to misconceptions. For this reason, the present work aims to sum up most of the common experimental techniques and procedures generally used in heterogeneous photocatalysis and to highlight the guidelines and the rules that a rigorous analysis and study of a photocatalytic system must follow. The paper focuses on the importance of standardization of photocatalytic experiments with special attention on the possibility to compare results obtained under different experimental conditions.
关键词： engineering aspects,Heterogeneous photocatalysis,standardization,characterization techniques,experimental procedures
更新于2025-09-23 15:21:01
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Materials Science and Technology of Optical Fabrication || Novel Process and Characterization Techniques
摘要： There are many conventional optical-fabrication process and characterization techniques, and they are well documented in the literature [1, 2]. These include the following: ? Interferometry techniques and test plating to measure surface ?gure, wedge, and parallelism ? Needle pro?lometry, white-light interferometry, and atomic force microscopy (AFM) to measure surface roughness ? Optical, confocal, and dark-?eld microscopy and visual inspection to measure surface quality ? Baume density ?oats, pH sensors, and particle-size analyzers to characterize polishing slurries ? Hardness testers to characterize lap materials, particularly pitch In this chapter, some novel techniques (and perhaps obscure techniques) that provide additional insight into the optical-fabrication process are described. Chapters 2–5 focused on the phenomena that govern the basic properties of a workpiece during and after optical fabrication, namely surface ?gure, surface quality, surface roughness, and material removal rate. The novel process and characterization techniques explored in this chapter are described for an optical-fabrication engineer or an optician who might wish to use them.
关键词： optical-fabrication,AFM,interferometry,characterization techniques,polishing slurries
更新于2025-09-09 09:28:46
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A Mechanistic View of the Main Current Issues in Photocatalytic CO2 Reduction
摘要： After 40 years of research on photocatalytic CO2 reduction, there are still many unknowns about its mechanistic aspects even for the most common TiO2-based photocatalytic systems. These uncertainties include the pathways inducing visible-light activity in wide-band-gap semiconductors; the charge transfer between semiconductors and plasmonic metal nanoparticles; the unambiguous determination of the origin of C-bearing products; the very first step in the activation of the CO2 molecule; the factors determining the selectivity; the reasons of photocatalyst deactivation; the closure of the catalytic cycle by the hole-scavenging reagent; and the detailed reaction pathways and the most suitable techniques for their determination. This perspective discusses these controversial issues based on the most relevant investigations reported so far. For that purpose, we have tried to view the complex CO2 reduction in a holistic manner, considering today’s state-of-the-art approaches, strategies and techniques for the study of one of the hottest topics in energy research.
关键词： Advanced characterization techniques,CO2 reduction,Photocatalysis,Artificial photosynthesis,Reaction mechanism,Charge transfer
更新于2025-09-04 15:30:14
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Liquid‐Crystal High‐Frequency Microwave Technology: Materials and Characterization
摘要： Ever since the advent of microwave technology, tunable devices, such as phase shifters, resonators, and antennas, have been indispensable in applications requiring radiofrequency signal filtering, beam shaping, or steering. This necessity becomes even more relevant in view of a new era in high-bandwidth wireless communications in 5G networks, satellite links, and advanced radars for sensing and safety. As the operating frequency is pushed toward the millimeter-wave range or beyond, the performance of traditional microwave tunable elements, such as PIN diodes, micro-electromechanical system switches, ferrites, or ferroelectric films, degrades, while their fabrication complexity and cost increases. In this respect, liquid crystals present a promising solution, as they provide continuous tuning, low dielectric constants, moderate losses, low dispersion, and potentially low cost. Here, a comprehensive overview of the available microwave liquid crystal materials is provided, including their key application-relevant properties, and the techniques employed for their characterization, focusing on the spectrum above 1 GHz. Their performance metrics in terms of dielectric constant tunability, response speed, insertion losses are discussed and guidelines for their selection in different microwave applications are provided. Moreover, the differences observed in the experimental data regarding their characterization are highlighted and possible sources of the observed discrepancies are discussed.
关键词： microwave technology,liquid crystals,microwave characterization techniques
更新于2025-09-04 15:30:14