NiFe-layered Double Hydroxide/Vertical Bi₂WO₆ Nanoplate Arrays with Oriented {001} Facets Supported on ITO Glass: Improved Photoelectrocatalytic Activity and Mechanism Insight

The hole oxidation of Bi2WO6 occurs on Bi or O sites, thus, enhancing the proportion of {001} facets of Bi2WO6 in photocatalysis has received increased attention because of its promotion of the hole oxidation. In this work, we successfully fabricated {001} facets highly exposed Bi2WO6 nanoplate arrays (Bi2WO6 NAs) photoelectrode growing on indium tin oxides (ITO) substrate in situ. After electrochemical deposition of NiFe-layered double hydroxide (LDH) on Bi2WO6 NAs, NiFe-LDH/Bi2WO6 NAs photoelectrode was also obtained for the first time. Bi2WO6 with a large proportion of {001} facets facilitate the photocatalytic oxidation reactions, and NiFe-LDH can induce photogenerated holes transfer from Bi2WO6 to NiFe-LDH simultaneously. The NiFe-LDH/Bi2WO6 NAs photoelectrode presents superior photoelectrochemical properties than pure Bi2WO6 NAs photoelectrode, which was characterized by transient photocurrent and electrochemical impedance spectroscopy (EIS) systematically. Taking bisphenol A (BPA) as a model pollutant, the NiFe-LDH/Bi2WO6 NAs photoelectrode exhibits much higher photocatalytic (PC) and photoelectrocatalytic (PEC) degradation activity than Bi2WO6 NAs photoelectrode. The PEC degradation rate of NiFe-LDH/Bi2WO6 NAs photoelectrode is 2.1 times and 4.7 times that of Bi2WO6 NAs photoelectrode under simulated solar light illumination and visible light illumination, respectively. This work proposes a new approach to construct highly efficient photoelectrode for contaminant purification.