Suggested terms and definitions in photocatalysis and radiocatalysis

Abstract

This document has two principal goals. First, it summarizes some of the issues that pertain to the complexities encountered in photocatalysis. Secondly, it presents suggested terms and definitions proposed to describe those phenomena, which fall under the umbrella of “photocatalysis” and “radiocatalysis”. A distinction is made between the different phenomena that are related to either or both photochemistry and photocatalysis, and to radiation chemistry and radiocatalysis. Consistent definitions of terms in these areas are given. Definitions of important parameters that describe photocatalytic and radiocatalytic phenomena quantitatively are also proposed. As with the related Glossary of Terms in Photochemistry, this document is a dynamic working document to provide the base for lively discussion and debate by the interested community. The terms and definitions will no doubt need to be revisited from time to time as the fields of photocatalysis and radiocatalysis progress and new discoveries reported. Some of the terms used in photochemistry are also given for completion, either verbatim or modified to address the issues of photocatalysis.

A study of process variables for the photocatalytic degradation of rhodamine B

“…Visible light is preferentially absorbed by the dye, which needs to be adsorbed by the catalyst in order to inject the electrons to begin the photocatalytic reaction. This activation mechanism is known as photoassisted (Serpone and Emeline, 2002) and is strongly dependent on the dye adsorption.…”

Photophysical Processes Related to Photoadsorption and Photocatalysis on Wide Band Gap Solids: A Review

“…The Scheme (Figure 3) displays some typical events related to photoadsorption and photocatalysis which occur in the bulk in the near surface area [1] and at the surface of wide band gap solids under illumination. The Scheme has been firstly presented in [13].…”

“…The heterogeneous photocatalysis can be defined as "Photocatalysis taking place at the interfacial boundary between two phases (solid-liquid; solid-gas; liquid-gas)" [1]. Symbolically photocatalytic reaction is expressed by the equation…”

“…In the same manner, photoadsorption defined as "adsorption, typically chemisorption (i.e., a stoichiometric reaction of adsorbate molecules with a solid surface), initiated by light absorbed either by the adsorbate or by the adsorbent," [1] can be presented as A + Cat +hν −→ A Cat (2) where A are adsorbate molecules and ACat are photoadsorbed species. Note, eq.…”

“…(2)). By definition, photoexcitation is "the act by which an excited state is produced in an entity (molecule or solid photocatalyst) by the absorption of ultraviolet, visible or infrared radiation [1]. In turn, in the light of photoexcitation of photocatalyst, the concept of surface photoadsorption (photocatalytic) center will be discussed in some details.…”