Template-free fabrication of BiFeO3 nanorod arrays: multiferroic and photo-electrochemical performances.

: BiFeO3 has been widely investigated in many forms and morphologies because of both multiferroic and photovoltaic properties. However, direct growth of vertically aligned BiFeO3 nanorods on an underlying substrate has remained a challenge. In this work, we report template free growth of vertically aligned BiFeO3 nanorods on Fluorine doped Tin Oxide (FTO) coated glass substrate. This has been achieved by a two-step process, in which FeOOH nanorods are grown by chemical bath deposition and converted into BiFeO3 using Bismuth (Bi) coating by physical vapour deposition (PVD). Both DC sputtering and thermal evaporation are attempted under PVD and the results suggest that Bismuth deposited by DC sputtering leads to well-defined BFO nanorods, which shows superior performance in both multiferroic and photoelectrochemical studies. Piezoelectric force microscopy data shows the signature butterfly loop that confirms piezoelectric behaviour with a d33 value of 8 pmV-1 in the BFO nanorods grown by DC sputtering. Further, the M-H hysteresis curve for the same samples reveals remanent magnetization (Mr) value of 0.54 emu cc-1 and antiferromagnetic nature at room temperature. Finally, a stable photocurrent density of 0.05 mA cm-2 is achieved at 0.8 V vs Ag/AgCl under 1 Sun illumination. This work opens up new avenues for BiFeO3 in applications involving 1D nanostructures.