Polydopamine-Mediated Contact-Electro-Catalysis for Efficient Partial Oxidation of Methane.

The direct conversion and efficient utilization of methane pose a critical scientific challenge. Indirect activation via reactive oxygen species (ROS) offers a high probability of contact with methane and conversion efficiency under mild conditions. However, reported product yields are suboptimal due to challenges in activating oxygen and facilitating mass transfer in suspension systems. We propose the use of contact-electro-catalysis (CEC), employing polydopamine (PDA) as a catalyst that undergoes electron transfer with oxygen under ultrasound, generating ROS that drives the partial oxidation of methane (POM). Corresponding experimental results indicate that CHOH and most HCHO are produced directly from CH. Furthermore, through in situ characterizations, we have shown that light pretreatment of the catalysts in an oxygenated atmosphere facilitates the forming of more C=O functional groups with strong electron-withdrawing properties, thereby significantly enhancing overall product yields, particularly for CHOH. Within two hours, product yields reach 1.5 mmol g for HCHO and 0.9 mmol g for CHOH. This work introduces a novel approach for efficient POM, while highlighting the distinctive catalytic properties of PDA.