Duet Fe3C and FeNx Sites for H2O2 Generation and Activation toward Enhanced Electro-Fenton Performance in Wastewater Treatment

Heterogeneous electro-Fenton (HEF) reaction has been considered as a promising process for real effluent treatments. However, the design of effective catalysts for simultaneous H2O2 generation and activation to achieve bifunctional catalysis for O2 toward •OH production remains a challenge. Herein, a core-shell structural Fe-based catalyst (FeNC@C), with Fe3C and FeN nanoparticles encapsulated by porous graphitic layers, was synthesized and employed in a HEF system. The FeNC@C catalyst presented a significant performance in degradation of various chlorophenols at various conditions with an extremely low level of leached iron. Electron spin resonance and radical scavenging revealed that •OH was the key reactive species and FeIV would play a role at neutral conditions. Experimental and density function theory calculation revealed the dominated role of Fe3C in H2O2 generation and the positive effect of FeNx sites on H2O2 activation to form •OH. Meanwhile, FeNC@C was proved to be less pH dependence, high stability, and well-recycled materials for practical application in wastewater purification.