Periodate Activation by Contact-Electrification for Organic Pollutant Degradation: Performance and Mechanisms

Contact-electro-catalysis (CEC) shows significant potential for integration with advanced oxidation processes (AOPs), but the full scope of its synergistic benefits and underlying mechanisms remains insufficiently elucidated. Here, we developed a CEC-AOP system by leveraging CEC to activate periodate (PI) for the degradation of organic contaminants. The resultant CEC-periodate (CEC-PI) system exhibited outstanding oxidation kinetics (kobs = 0.053 ± 0.0060 min–1) and an oxidant activation efficiency of ∼30% for sulfamethoxazole (SMX) degradation. This CEC-PI system exhibited superior performance compared to CEC integration with other common oxidants (e.g., hydrogen peroxide, peracetic acid, peroxymonosulfate, and peroxydisulfate) for SMX removal under identical conditions. Quenching experiments and electron paramagnetic resonance spectroscopy verified that 1O2 and O2·– are the primary reactive oxygen species (ROS) responsible for SMX degradation, with O2·– potentially serving as a precursor for 1O2 generation. Electrochemical analyses confirmed the essential role of contact electrons in activating the oxidant, while density functional theory calculations demonstrated a significant reduction in the electron-transfer energy barrier between the catalyst and the oxidant due to the CEC process. Furthermore, the system demonstrated low energy consumption, maintained over 90% degradation efficiency after five consecutive cycles, and showed effective removal of multiple organic contaminants, indicating a strong potential for scale-up applications. By combining triboelectric materials with periodate under ultrasonication, this work not only clarifies the oxidative efficacy of the CEC-PI system but also reveals, for the first time, the underlying mechanism of CEC-enhanced periodate activation. These findings provide an important theoretical basis for expanding the application of CEC in the control of environmental pollutants.