Sulfur treated 1D anodic TiO2 nanotube layers for significant photo- and electroactivity enhancement

Abstract

n this work, we show that sulfur treated 1D anodic TiO2nanotube layers lead to improved photo-electrochemical and catalytic properties compared to the blank nanotube layers. This treatment wasperformed in the evacuated quartz ampoules in the temperature range from 250 to 450◦C. Inspectionof the sulfurized nanotube layers via scanning electron microscopy (SEM) and X-ray diffraction (XRD)has disclosed a gradual crystal growth within nanotube walls, represented by TiS2or TiS3phases. Opti-mally sulfurized TiO2nanotube layers exhibit 3 times enhanced photocurrent in the UV spectral region,compared to the blank counterpart, with a shift of the light absorption up to the wavelength of 550 nm.In addition, the photocatalytic decomposition of a methylene blue aqueous solution using a wavelengthof 365 nm is gradually improved with increasing sulfurization temperature. The highest photocatalyticdecomposition rate is 2.3 times larger compared to the blank TiO2nanotube layer. The application ofsulfurized TiO2nanotube layers for the electrocatalytic hydrogen evolution is also discussed.