Low temperature fabrication of FeO nanorod film coated with ultra-thin g-CN for a direct z-scheme exerting photocatalytic activities.

We engineered high aspect ratio FeO nanorods (with an aspect ratio of 17 : 1) coated with g-CN using a sequential solvothermal method at very low temperature followed by a thermal evaporation method. Here, the high aspect ratio FeO nanorods were directly grown onto the FTO substrate under relatively low pressure conditions. The g-CN was coated onto a uniform FeO nanorod film as the heterostructure, exhibiting rational band conduction and a valence band that engaged in surface photoredox reactions by a direct z-scheme mechanism. The heterostructures, particularly 0.75g-CN@FeO nanorods, exhibited outstanding photocatalytic activities compared to those of bare FeO nanorods. In terms of 4-nitrophenol degradation, 0.75g-CN@FeO nanorods degraded all of the organic pollutant within 6 h under visible irradiation at a kinetic constant of 12.71 × 10 min, about 15-fold more rapidly than bare FeO. Further, the hydrogen evolution rate was 37.06 μmol h g, 39-fold higher than that of bare FeO. We suggest that electron and hole pairs are efficiently separated in g-CN@FeO nanorods, thus accelerating surface photoreaction a direct z-scheme under visible illumination.