Ti-doped α-Fe₂O₃ nanorods with controllable morphology by carbon layer coating for enhanced photoelectrochemical water oxidation

Abstract

Ti-doped α-Fe₂O₃ nanorods (NRs) with carbon layer coating were fabricated for photoelectrochemical (PEC) water oxidation. The α-Fe₂O₃ NRs were grown on the surface of a Ti foil substrate by hydrothermal synthesis. Ti⁴⁺ was diffused from the Ti substrate and doped into the α-Fe₂O₃ NRs by sintering at 800 °C. The presence of Fe²⁺ in the α-Fe₂O₃ lattice was achieved by annealing the NRs in a lack of oxygen atmosphere, e.g. in argon. The co-existence of Ti⁴⁺ and Fe²⁺ results in significant enhancement of the PEC performance compared with the hematite NRs obtained by annealing in air, showing the absence of Fe²⁺. The carbon layer coating was conducted by the carbonization of glucose. Impressively, the coated carbon layer can not only facilitate the charge transfer of the photogenerated carriers but also effectively restrain the structural aggregation of the NRs upon high temperature sintering. The carbon layer coated NRs exhibited 1.2 times higher photocurrent density than the uncoated NRs due to the reduced charge recombination and well-distinct NR structures.