Mechanism in chlorine‐enhanced Pd catalyst for H 2 O 2 in situ synthesis in electro‐Fenton system

Palladium‐based catalysts have been widely employed in the electro‐Fenton process for in situ generation of H 2 O 2 . However, the process is still far from being practical on a large scale. In this work, a series of Cl x FePd/γ‐Al 2 O 3 /Al catalysts were prepared by a three‐step‐impregnation method. They exhibited excellent activity in H 2 O 2 in situ synthesis and high efficiency in phenol degradation. The characterization results showed that Cl could assist in increasing the content of Pd 0 and reducing the isoelectric point of catalysts, which led to the drastic promotion in the synthesis of H 2 O 2 . Theoretical calculations further demonstrated that Cl doping could facilitate the main reaction in H 2 O 2 synthesis, as well as inhibit side reactions such as dissociation of the OO bond. Furthermore, kinetic models were proposed and fitted. A plausible reaction mechanism as well as degradation pathways were elaborated based on electron spin resonance and gas chromatography–mass spectrometry results. These findings illustrate the value of palladium‐based Cl x FePd/γ‐Al 2 O 3 /Al catalysts for their application in the electro‐Fenton process.