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-FeO) nanoarrays on fluorine-doped SnO glass (FTO). The morphology, crystalline phase, optical property and surface chemical states of the fabricated α-FeO photoelectrode were characterized by scanning electron microscopy, X-ray diffraction, ultraviolet visible spectroscopy and X-ray photoelectron spectroscopy correspondingly. The α-FeO photoelectrode exhibits excellent photoelectrochemical (PEC) response toward hydrogen peroxide (HO) 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-FeO photoelectrode shows satisfying reproducibility, stability, selectivity and good feasibility for real samples. Mechanism analysis indicates, comparing with HO, HO possesses much more fast reaction kinetics over α-FeO 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 HO in aqueous solution, will stimulate us to further optimize the surface structure of α-FeO to gain highly efficient α-FeO based sensors.