Effects of particle dispersion on the measurement of semi-conductor photocatalytic activity

Fourfold changes in the rate of salicylic acid degradation were induced when the same catalyst was milled for increasing times. This implies that two catalysts which differ in activity by a factor of four may do so because of differences in their dispersion rather than because they have different intrinsic activities. It is also shown the relative performance of two catalysts which differ in their surface properties changes when they are milled. However, the relative activities of a series of iron doped catalysts with no deliberate differences in surface properties were not changed by milling.