On the Problem of Comparing Rates or Apparent Quantum Yields in Heterogeneous Photocatalysis

Breaking the impasse: Earlier this year Maschmeyer and Che outlined an approach for normalizing and comparing the apparent quantum yields (AQY) for hydrogen photogeneration catalyzed by semiconductor powders. In the plot of photocatalyst concentration versus AQY they proposed that the linear region was the most appropriate region for comparison. In his Correspondence Kisch refutes this proposal and states that the area at the onset of the plateau region (B) in a plot of catalyst concentration versus reaction rate is relevant. Maschmeyer and Che explain their rationale and conclude that the discussion has arisen because of different emphases in studying photocatalysis.