Low temperature fabrication of Fe 2 O 3 nanorod film coated with ultra-thin g-C 3 N 4 for a direct z-scheme exerting photocatalytic activities.

We engineered high aspect ratio Fe 2 O 3 nanorods (with an aspect ratio of 17 : 1) coated with g-C 3 N 4 using a sequential solvothermal method at very low temperature followed by a thermal evaporation method. Here, the high aspect ratio Fe 2 O 3 nanorods were directly grown onto the FTO substrate under relatively low pressure conditions. The g-C 3 N 4 was coated onto a uniform Fe 2 O 3 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-C 3 N 4 @Fe 2 O 3 nanorods, exhibited outstanding photocatalytic activities compared to those of bare Fe 2 O 3 nanorods. In terms of 4-nitrophenol degradation, 0.75g-C 3 N 4 @Fe 2 O 3 nanorods degraded all of the organic pollutant within 6 h under visible irradiation at a kinetic constant of 12.71 × 10 -3 min -1 , about 15-fold more rapidly than bare Fe 2 O 3 . Further, the hydrogen evolution rate was 37.06 μmol h -1 g -1 , 39-fold higher than that of bare Fe 2 O 3 . We suggest that electron and hole pairs are efficiently separated in g-C 3 N 4 @Fe 2 O 3 nanorods, thus accelerating surface photoreaction via a direct z-scheme under visible illumination.