The Importance of the Macroscopic Geometry in Gas‐Phase Photocatalysis

• Published in: Advanced science 2022-05, Vol.9 (13), p.e2105363-n/a
• Main Authors: Matter, Fabian, Niederberger, Markus
• Format: Article
• Language: English
• Subjects: aerogels; Catalysis; Chemical reactions; Crystal structure; Environmental impact; Gas flow; Gases; Geometry; monoliths; Morphology; Nanoparticles; Optimization; Particle size; Photocatalysis; photoreactors; Pollutants; Review; Reviews; Semiconductors; Titanium
• ISSN: 2198-3844; 2198-3844
• DOI: 10.1002/advs.202105363

Photocatalysis has the potential to make a major technological contribution to solving pressing environmental and energy problems. There are many strategies for improving photocatalysts, such as tuning the composition to optimize visible light absorption, charge separation, and surface chemistry, ensuring high crystallinity, and controlling particle size and shape to increase overall surface area and exploit the reactivity of individual crystal facets. These processes mainly affect the nanoscale and are therefore summarized as nanostructuring. In comparison, microstructuring is performed on a larger size scale and is mainly concerned with particle assembly and thin film preparation. Interestingly, most structuring efforts stop at this point, and there are very few examples of geometry optimization on a millimeter or even centimeter scale. However, the recent work on nanoparticle‐based aerogel monoliths has shown that this size range also offers great potential for improving the photocatalytic performance of materials, especially when the macroscopic geometry of the monolith is matched to the design of the photoreactor. This review article is dedicated to this aspect and addresses some issues and open questions that arise when working with macroscopically large photocatalysts. Guidelines are provided that could help develop novel and efficient photocatalysts with a truly 3D architecture. The use of macroscopic monolithic photocatalysts holds great potential for technological exploitation if the geometry of the photocatalyst is optimally adapted to that of the photoreactor. This review article is devoted to this aspect and addresses some problems and open questions that could contribute to the development of novel and efficient photocatalysts with a truly 3D architecture.