Enhanced photoelectrochemical performance of BiVO4 nanoparticle-modified TiO2 nanorod arrays

Abstract

A wide-spectrum responsive one-dimensional (1-D) TiO2@BiVO4 heterostructured array (HA) photoelectrode was successfully prepared using an easy hydrothermal approach and subsequent stepwise spin–coating. BiVO4 nanoparticles (NPs) were uniformly coated onto TiO2 nanorods (NRs) surface. The photoelectrochemical (PEC) performance can be optimized by controlling the number of the stepwise spin-coating cycles. The appropriate stepwise spin-coating cycles number was crucial for obtaining a perfect TiO2@BiVO4 HA photoelectrode with enhanced PEC performance. Compared with the bare TiO2 NR array (NRA) photo-electrode, TiO2@BiVO4-8 HA photoelectrode (acquired in 8 cycles) exhibited the significantly improved photocurrent density (from 0.19 to 1.21 mA·cm−2 at 1.0 V vs. the saturated calomel electrode (SCE), approximately a 6-fold increase for that of the pure TiO2 NRA photoanode), increased electron lifetime (from 1.26 to 6.09 ms), reduced initial potential (from – 0.22 V to – 0.57 V (vs. SCE)), and enhanced photoconversion efficiency (from 6.3 % to 32.7 % at 360 nm). The performance improvement is given the credit to the unique 1-D well-arranged heterostructure of the photoelectrodes and the appropriate BiVO4 NPs coating amount onto TiO2 NRs surface.