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.