Trace FeCu@PC Derived from MOFs for Ultraefficient Heterogeneous Electro-Fenton Process: Enhanced Electron Transfer and Bimetallic Synergy

A Fe0/Cu0-based bimetallic submicro-particle core with porous carbon (PC) shell hybrid rods, i.e., core–shell structured FeCu@PC-800/6, was successfully fabricated from the mixture of MIL-88B(Fe) and Cu-BDC through pyrolysis at 800 °C for 6 h and employed as novel heterogeneous electro-Fenton (Hetero-EF) catalysts to remove sulfamethazine (SMT). A trace dose catalyst (25.0 mg L–1) could achieve efficient catalytic activity (turnover frequency (TOFd), 3.92 L g–1 min–1) due to the synergy of catalytic reactivity among iron, copper, and PC, possessing the pseudo-first-order rate for SMT removal that was 3.27-foldsand 4.08-fold of the Fe@PC-800/6/Hetero-EF and Cu@PC-800/6/Hetero-EF process, respectively. According to experiments and density functional theory (DFT) calculations, Hetero-EF reactions enhanced by internal-microelectrolysis (IME) were proposed, in which Cu0 promoted the electrons transfer of Fe0 to PC while the introduced Cu+ could promote the decomposition of H2O2 and the cycle of Fe3+/Fe2+. A possible mechanism and SMT degradation pathway were suggested for this Hetero-EF process, confirming that the surface-bound hydroxyl radical played a major role. This FeCu@PC-800/6 catalyst was cost-effective and could be reused after thermal treatment in H2, demonstrating super efficiency for organic contaminants degradation by EF process.