ON THE USAGE OF TURNOVER NUMBERS AND QUANTUM YIELDS IN HETEROGENEOUS PHOTOCATALYSIS

This paper discusses two issues which have led to, and continue to cause, confusion in the heterogeneous photochemical literature: (i) turnover numbers (turnover rates, turnover frequencies) and (ii) quantum yields. Attention is called to the use of these two parameters when describing the catalytic activity of a photocatalyst on the one hand and the efficiency of a photon on the other. A parameter is defined (relative photonic efficiency) and a simple method is proposed which provides a means of validating data between experiments and between laboratories. In addition, the process efficiency can be assessed and the photocatalytic activity of different materials and a given photocatalyst material from various sources can be validated.