A novel,simple and effective method was developed for the detection of Cr6+ using a photoelectrochemical(PEC) sensor based on Fe∶TiO2 nanosheets in this paper.Fe∶TiO2 nanosheets was synthesized by hydrothermal method using C16H36O4Ti and FeF3 as raw materials,which were characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD) and UV absorption spectroscopy(UV-Vis).Electrochemical methods were adopted to characterize the modified electrode.And the test conditions for Fe doped amount,Fe∶TiO2 concentration and bias voltage were investigated.Under the illumination of light,the Fe∶TiO2 nanosheets reduced Cr6+ to Cr3+.When Cr3+ reacted with OH-,Cr(OH)3 was formed and deposited on the surface of the electrode,resulting in the decrease of photocurrent so as to achieve the purpose of detection.Results showed that the linear range of the sensor for detection of Cr6+ varied from 0.008 μmol/L to 100 μmol/L(r2=0.999 5),with a detection limit of 0.004 μmol/L.The sensor was applied in the detection of actual samples with good sensitivity and selectivity.The spiked recoveries were in the range of 99.3%-119% with relative standard deviations(RSD) of 2.3%-2.8%,indicating that the photoelectrochemical sensor has a great application potential in the selective detection of Cr6+.