Photoelectrochemical sensing and mechanism investigation of hydrogen peroxide using a pristine hematite nanoarrays

In this paper, a facile hydrothermal combined with subsequent two-step post-calcination method was used to fabricate hematite (α-Fe2O3) nanoarrays on fluorine-doped SnO2 glass (FTO). The morphology, crystalline phase, optical property and surface chemical states of the fabricated α-Fe2O3 photoelectrode were characterized by scanning electron microscopy, X-ray diffraction, ultraviolet visible spectroscopy and X-ray photoelectron spectroscopy correspondingly. The α-Fe2O3 photoelectrode exhibits excellent photoelectrochemical (PEC) response toward hydrogen peroxide (H2O2) in aqueous solutions, with a low detection limit of 20 μM (S/N = 3) and wide linear range (0.01-0.09, 0.3-4, and 6-16 mM). Additionally, the α-Fe2O3 photoelectrode shows satisfying reproducibility, stability, selectivity and good feasibility for real samples. Mechanism analysis indicates, comparing with H2O, H2O2 possesses much more fast reaction kinetics over α-Fe2O3 surface, thus the recombination of photogenerated charges are reduced, followed by much more photogenerated electrons are migrated to the counter electrode via external circuit. The insight on the enhanced photocurrent, which is corelative to the concentration of H2O2 in aqueous solution, will stimulate us to further optimize the surface structure of α-Fe2O3 to gain highly efficient α-Fe2O3 based sensors.