Nitrogen-doped carbon dots as electron “bridge” in heterostructure of alpha-Fe2O3/NCDs/g-C3N4 for efficient degradation of indole using heterogeneous photo-Fenton

A special component, acting as “bridge” in composite photocatalyst, can remarkably improve the transfer and migration of charges by strengthening interfacial contact and constructing conductive channels. Nitrogen-doped carbon dots (NCDs) may be suitable for the bridge due to great conductivity, sufficient surface groups and more delocalized electrons. Here, we fabricated a composite of α-Fe2O3/NCDs/g-C3N4 for heterogeneous photo-Fenton degradation of indole and investigated the “bridge” roles of NCDs. Although the introduction of NCDs reduced surficial adsorption and light absorption abilities, the composite has a significant improvement in photocurrent density and EIS spectra, which were attributed to the bridge of NCDs between α-Fe2O3 and g-C3N4 through Fe-O-C and N-CN bonds. Besides, great conductivity of NCDs is another important factor for the transfer channels of charges. Finally, a Z-scheme mechanism was proposed for explanation of the transfer and migration of charges.