In this study, WO<inf>3</inf>nanoplates modified by doping with gadolinium (Gd) were synthesized by a hydrothermal method. The effect of the rare-earth element on the photoelectrochemical (PEC) performance of WO<inf>3</inf>one- or two-dimensional (2D) materials was examined. Scanning electron microscopy, transmission electron microscopy, and X-ray diffraction were employed to examine the crystal phase and morphology of the Gd-doped nanoplates thus prepared. Results of UV-vis spectroscopy, valence-band (VB) X-ray photoelectron spectroscopy, and Mott-Schottky analyses indicated that the conduction band and VB potentials of WO<inf>3</inf>shifted to negative values. Linear sweep voltammetry results indicated that the photocurrent density increased by 153% after modification by doping with Gd. In addition, the PEC properties of the WO<inf>3</inf>nanoplates obtained by the intensity-modulated photocurrent spectrum and incident photon-to-current conversion efficiency measurements indicated that modification by doping with Gd has a scintillating application in improving the PEC conversion properties of WO<inf>3</inf>-based 2D materials. ©2015 American Chemical Society.