External Electric Field-Enhanced Fenton-Like Reactivity of Multiprincipal Element Alloy

Benefiting from high configurational entropy and tunable composition, multiprincipal element alloys (MPEAs) have emerged as promising candidates for heterogeneous catalysis. Only recently have MPEAs been explored for peroxymonosulfate (PMS)-based Fenton-like reactions. In the past, it has been known that an external electric field (EEF) can accelerate Fenton-like reactions by transferring free electrons to PMS. Herein, MPEAs supported on carbon nanofibers (MPEA/CNFs) were synthesized to investigate the effects of EEF on their catalytic performance as well as the reaction mechanism. In the presence of EEF, the degradation rate increased 20-fold (k = 270.6 M^-1·min^-1) compared with the nonelectrified system, and metal leaching was significantly reduced (around 10 times), resulting in enhanced stability and excellent recyclability of the MPEA/CNFs catalyst. The improvement was attributed to the <i>in situ</i> generation of hydrogen peroxide (H₂O₂) by the CNF substrate in the presence of EEF. Surprisingly, the generated H₂O₂ was not decomposed into reactive species for pollutant degradation. Computational studies revealed that although the active site in MPEAs remained unchanged, the H₂O₂ was adsorbed onto the metal element adjacent to the active site, which significantly increased the binding energy between PMS and MPEA by 4.8 times, facilitating electron transfer and enhancing the nonradical pathway. This study offers valuable insights into the application and mechanism of MPEA catalysts in Fenton-like reactions.