In this study, TiO(2 )nanorod arrays (TNR), Ag quantum dots (QDs) sensitized with TNR TiO2/Ag, bismuth oxyhalide (BiOI) nanosheets, and Ag QDs co-modified with TNR and TiO2/BiOI/Ag (TBA) were prepared by a stepwise process. The morphological, structural, compositional, optical, photocatalytic (PC), and photoelectrochemical (PEC) properties of the samples were investigated. The TBA-2 sample exhibited the highest photocurrent density (281.8 mu A/cm(2)) and photodegradation efficiency (93.3%), with values 9.7 times and 2.25 times higher than those for TNR, respectively. The improvement in sample performance can be attributed to the formation of a heterojunction between BiOI and TiO2, thereby enhancing the absorption of visible light and improving the charge separation efficiency; Ag QDs limit interfacial electron-hole pair recombination. The experimental results show that TBA can effectively promote light-induced carrier transport and visible light absorption, while inhibiting the recombination rate of the electron-hole pairs, PEC, and PC.