Ultrafine α-Fe2O3 nanocrystals anchored on N-doped graphene: a nanomaterial with long hole diffusion length and efficient visible light-excited charge separation for use in photoelectrochemical sensing

The authors have coupled ultrafine α-Fe 2 O 3 nanocrystals to N-doped graphene (NG) to obtain a novel material for use in a photoelectrode. The presence of NG is shown to strongly affect the morphology and size of the α-Fe 2 O 3 nanocrystals formed on the NG sheets, and to improve their photoelectrochemical (PEC) activity. Interestingly, the PEC performance of the nanocomposite is closely correlated to the size of the α-Fe 2 O 3 nanocrystals in that small nanocrystals display better PEC properties. The photocurrent of α-Fe 2 O 3 -NG is nearly 3.3-fold stronger than that of α-Fe 2 O 3 nanocrystals. Based on the remarkable PEC performance of this nanocomposite, a PEC sensor was constructed for the sensitive determination of 1,4-dihydroxybenzene (HQ). Its photocurrent increases with the HQ concentration in the range from 3.0 nM to 3.3 μM, and the detection limit is 1.0 nM (at an S/N ratio of 3). In our perception, the study presented here can serve as a basis for a better understanding of the relationship between morphologies and PEC performance of such nanomaterials. Conceivably, it may be extended to other PEC sensing system and to other fields associated with nanotechnology. Ultrafine α-Fe 2 O 3 nanocrystals were prepared via coupling with N-doped graphene (NG) substances (α-Fe 2 O 3 -NG). They exhibit superior photoelectrochemical (PEC) performance and have been successfully utilized for PEC-based sensing.