▎ 摘　　要

The authors have coupled ultrafine alpha-Fe2O3 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 alpha-Fe2O3 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 alpha-Fe2O3 nanocrystals in that small nanocrystals display better PEC properties. The photocurrent of alpha-Fe2O3-NG is nearly 3.3-fold stronger than that of alpha-Fe2O3 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 mu M, 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.