Synergistic Coupling of Fe2O3 and Carbon Paper that Enables Photocatalytic Mineralization of Organic Contaminants in the Absence of Chemical Oxidants under Visible Light

Herein, we report that an engineered nanomaterial of Fe2O3-coated carbon paper (Fe2O3/CP) exhibits unusual activity for the complete photocatalytic degradation/mineralization of organic contaminants without needing any external chemical oxidants. The visible-light-induced degradation by the iron oxide-based photocatalyst without the assistance of chemical oxidants is very limited due to the short hole diffusion length of Fe2O3. The unique photocatalytic activity was only observed with Fe2O3/CP, whereas neither iron oxides nor bare CP alone exhibited any removal activity. Fe2O3/CP is a low-cost and nontoxic material consisting of earth-abundant elements only. Various spectroscopic and electrochemical characterizations suggest that the synergistic combination of Fe2O3 and CP facilitates the efficient charge separation across the Fe2O3–CP interface. Photogenerated electrons and holes are effectively separated into CP and Fe2O3, respectively. The surface oxygen-containing functional groups on CP seem to play a critical role as an electron acceptor, while the holes on Fe2O3 directly oxidize organic contaminants without generating hydroxyl radicals. Fe2O3/CP exhibited versatile photocatalytic activities for a variety of organic compounds, and it showed much higher photocatalytic activity than any other Fe2O3/carbon materials. The Fe2O3/CP nanocomposite working under visible light is proposed as a recoverable environmental photocatalyst that can remove aqueous organic contaminants without requiring external chemical oxidants.