The recent advances in electrocatalysis for oxygen reduction reaction (ORR) for proton exchange membrane fuel cells (PEMFCs) are thoroughly reviewed. This comprehensive Review focuses on the low- and non-platinum electrocatalysts including advanced platinum alloys, core shell structures, palladium-based catalysts, metal oxides and chalcogenides, carbon-based non-noble metal catalysts, and metal-free catalysts. The recent development of ORR electrocatalysts with novel structures and compositions is highlighted. The understandings of the correlation between the activity and the shape, size, composition, and synthesis method are summarized. For the carbon based materials, their performance and stability in fuel cells and comparisons with those of platinum are documented. The research directions as well as perspectives on the further development of more active and less expensive electrocatalysts are provided.
In this review, we highlight the use of organic photoredox catalysts in a myriad of synthetic transformations with a range of applications. This Overview is arranged by catalyst class where the photophysics and electrochemical characteristics of each is,discussed to underscore the differences and advantages to each type of single electron redox agent. We highlight both net reductive and oxidative as well as redox neutral transformations that can be accomplished using purely organic photoredoxactive catalysts. An overview of the basic photophysics and electron transfer theory is presented in order to provide a comprehensive guide for employing this class Of catalysts in photoredox manifolds.
Schneider et al examine the mechanisms and materials of understanding titanium dioxide (TiO2) photocatalysis. They focus on topics such as time-resolved analysis of the photocatalytic process, the synthesis of TiO2 nanoparticles and nanoparticulate structures, and titanium-based single-site photocatalysts.
The halogen bond occurs when there is evidence of a net attractive interaction between an electrophilic region associated with a halogen atom in a molecular entity and a nucleophilic region in another, or the same, molecular entity. In this fairly extensive review, after a brief history of the interaction, we will provide the reader with a snapshot of where the research on the halogen bond is now, and, perhaps, where it is going. The specific advantages brought up by a design based on the use of the halogen bond will be demonstrated in quite different fields spanning from material sciences to biomolecular recognition and drug design.
Lee et al explore one-dimensional titanium oxide (TiO2) nanotubes. They focus on the growth techniques for TiO2 nanotubes, ordered TiO2 nanotube arrays, the properties of TiO2 nanotubes, and the modification and applications of TiO2 nanotubes.
Yi Ma et al examine titanium dioxide (TiO2)-based nanomaterials for photocatalytic fuel generations. They address various topics such as the basic properties of TiO2 semiconductor photocatalysts, the hydrogen generation of TiO2-based photocatalysts, and the photoreduction of CO2 to solar fuels on TiO2-based photocatalysts.
The interaction between an electronically excited photocatalyst and an organic molecule can result in the genertion of a diverse array of reactive intermediates that can be manipulated in a variety of ways to result in synthetically useful bond constructions. This Review summarizes dual-catalyst strategies that have been applied to synthetic photochemistry. Mechanistically distinct modes of photocatalysis are discussed, including photoinduced electron transfer, hydrogen atom transfer, and energy transfer. We focus upon the cooperative interactions of photocatalysts with redox mediators, Lewis and Bronsted acids, organocatalysts, enzymes, and transition metal complexes.