The Role of Singlet Oxygen, Superoxide, Hydroxide, and Hydrogen Peroxide in the Photoelectrochemical Response of Phenols at a Supported Highly Fluorinated Zinc Phthalocyanine

Photoelectrochemical (PEC) sensing of phenolic compounds using singlet oxygen (O-1(2))-generating photocatalysts has emerged as a powerful detection tool. However, it is currently not known how experimental parameters, such as pH and applied potential, influence the generation of reactive oxygen species (ROS) and their photocurrents. In this article, the PEC response was studied over the 6 to 10 pH range using a rotating (ring) disk (R(R)DE) set-up in combination with quenchers, to identify the ROS formed upon illumination of a supported photosensitizer, F64PcZn. The photocurrents magnitude depended on the applied potential and the pH of the buffer solution. The anodic responses were caused by the oxidation of O-2(.-), generated due to the quenching of O-1(2) with -OH and the reaction of O-3(2) with [F64Pc(3-)Zn]. The cathodic responses were assigned to the reduction of O-1(2) and O-2(.-), yielding H2O2. These insights may benefit O-1(2) - based PEC sensing applications.