Construction of TiO2 nano-tubes arrays coupled with Ag2S nano-crystallites photoelectrode and its enhanced visible light photocatalytic performance and mechanism

In the present work, narrow band gap Ag2S nano-crystallites decorated TiO2 nanotubes arrays (Ag2S NCs/TiO2 NTAs) photoelectrode was successfully constructed through anodization, followed by successive ionic layer adsorption and reaction (SILAR) strategy. Subsequently, morphologies and chemical structures were investigated through scanning electron microscope (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). In addition, the optical and photoelectrochemical (PECH) properties were recorded through Ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS), transient photocurrent density and Mott-Schottky measurements. Furthermore, the photocatalytic (PC) performance was evaluated through the yield of hydroxyl (·OH) radicals and degradation of methyl blue under visible light illumination. All results indicated that Ag2S NCs/TiO2 NTAs photoelectrode exhibited intense visible light absorbance, high transient photocurrent of 0.098 mA · cm−2 and charge carrier concentration of 1.58 × 1019 · cm−3, as well as effective PC performance of 83.6% for the degradation of methyl blue. Besides,  · OH radicals was the dominated responsible active species during the PC process. The enhanced visible light PC performance was mainly attributed to the intense visible light absorbance and high charge carrier separation efficiency.