Effect of radio frequency sputtering power on W-TiO2 nanotubes to improve photoelectrochemical performance

The present study aims to determine the optimum radio frequency (RF) sputtering power to obtain the desired W-TiO2 nanotubes for the best photoelectrochemical (PEC) performance. Tungsten (W) was deposited on titania (TiO2) nanotube arrays via RF sputtering technique under different sputtering powers from 50 to 250 W. The optimum content of W on TiO2 nanotube arrays play a significant role in maximizing the photocurrent generation efficiency to promote charge separation by accumulation of photogenerated electrons. The sputtering power below 180 W exhibited high-ordered and unbroken TiO2 nanotube arrays. However, the sputtering power over 180 W exhibited broken nanotube arrays and an oxide layer was formed due to the impact of high energy ions accelerated by a high sputtering power. The TiO2 nanotube arrays sputtered with tungsten at 50 W showed a better photocurrent density (1.55 mA/cm(2)), with a photoconversion efficiency of 2.2% in the PEC performance among the samples due to the effective charge separation and reduced recombination center in the resultant W-TiO2 nanotubes.