Intercalation of Nanosized FeC in Iron/Carbon To Construct Multifunctional Interface with Reduction, Catalysis, Corrosion Resistance, and Immobilization Capabilities.

As a robust reducing system in industrial wastewater treatment, iron/carbon (Fe/C) microelectrolysis suffers from surface passivation and low utilization efficiency. Herein, we introduced FeC into the Fe/C system to develop a core-shell Fe/FeC/C nanorod with a multifunctional interface (FeC/C) providing reduction, catalysis, adsorption, and corrosion resistance. The results proved that the fabricated Fe/FeC/C possesses 5.6 times higher reduction capacity (220 mg/g) for Cr(VI) reduction but a relatively lower Fe leakage (2.7 mg/L) than Fe/C. On the basis of the results of electrochemical characterization (Tafel polarization curves and electrochemical impedance spectroscopy), the corrosion-resistant FeC/C shell can significantly prevent surface passivation of the Fe core, whereas FeC efficiently catalyzes electron transfer from the inner Fe to the external carbon surface. Moreover, the reductive species involved in Cr(VI) removal were identified as hydrogen atoms, adsorbed Fe(II) ions, and electrons tunneling from Fe. STEM, XPS, and Mössbauer spectroscopies were further adopted to characterize the interface reaction of Fe/FeC/C during the Cr(VI) removal process. Finally, the reaction mechanism for Cr(VI) reduction over Fe/FeC/C was proposed, and the distribution of active sites was inferred.