Interference effects in H₂O₂ quantification: A comparative study of three common methods in photocatalytic systems

Precise measurement of the production of H₂O₂ during the photocatalytic process is important for the performance assessment of photocatalysts. N,N-diethyl-1,4-phenylenediamine (DPD) method, iodometry method and cerium sulfate Ce(SO₄)₂ titration method are currently the most widely employed in relevant research. However, the effectiveness and reliability of these methods have rarely been systematically investigated. In this study, using g-C₃N₄, TiO₂, ZnSe and resorcinol formaldehyde (RF) as model photocatalysts, a comparative analysis of these three methods was conducted. The results demonstrate that certain byproducts are formed during the production of H₂O₂, and they act as interferents that compromise the accuracy of the measurement. Although Ce(SO₄)₂ titration method is accurate for standard H₂O₂ solutions, it usually overestimates the production of H₂O₂ in the photocatalytic process. Nitrogen species, particularly NO₂^-, are key interferents influencing the measurement. Moreover, the iodometric method is highly susceptible, as NO₂^- amplifies the formation of through a catalytic cycle, which induces a significant and time-dependent overestimation. Among the methods, the DPD method demonstrates excellent anti-interference capability.