Structure and photoelectrochemical performance of barium titanate-based coaxial nanorod arrays under improved ferroelectric polarization

The combination of photocatalysts and ferroelectrics with spontaneous polarization can low the electron-hole pair complexation rate. In this work, barium titanate-based coaxial nanorod arrays including TiO 2 /Ba 1-x La x TiO 3 and TiO 2 /Ba 1-x La x TiO 3 /TiO 2 were rationally designed and prepared using TiO 2 nanorod arrays as both template and reactants using an in-situ reaction combined with sol-gel and dip-coating methods. The nanorod arrays exhibit an average length of 500 nm. A piezoelectric coefficient d 33 of 53 pm/V of TiO 2 /Ba 0.94 La 0.06 TiO 3 is achieved after doping La 3+ with the concentration of 6 %. The photocurrent density of the TiO 2 /Ba 0.94 La 0.06 TiO 3 /TiO 2 nanorod array is 8.7 and 1.6 times higher than those of the TiO 2 /TiO 2 and TiO 2 /BaTiO 3 /TiO 2 nanorod array, respectively. The photocurrent density of the TiO 2 /Ba 0.94 La 0.06 TiO 3 /TiO 2 nanorod arrays is expanded by a factor of 6.9 under positive polarization at 3 V. After ultrasonic poling, the photocurrent density of the TiO 2 /Ba 0.94 La 0.06 TiO 3 /TiO 2 nanorod array increases by a factor of 2.2. The boosted photoelectrochemical properties are attributed to the enhanced separation and migration of the photogenerated carriers under the improved ferroelectric polarization by ion doping and external field poling. This study provides a strategy to design novel ferroelectric-based photocatalysts with excellent photoelectrochemical properties.