Photo-to-current response of Bi2Fe4O9nanocrystals synthesized through a chemical co-precipitation process

Abstract

Pure-phase Bi₂Fe₄O₉ nanocrystals of mullite-type structure were synthesized through a facile chemical co-precipitation process. The nanocrystals consist of nanorods with transverse size of 100–200 nm and nanoparticles of 80–150 nm in dimension. The nanorods are preferentially grown along [001] and show flat side facets (110) and (10). The nanocrystals exhibit two narrow bandgaps of 2.05 eV and 1.53 eV. A steady photocurrent of 37 μA cm⁻² was observed in the Bi₂Fe₄O₉ nanocrystals under visible-light irradiation. The photo-to-current response of Bi₂Fe₄O₉ has not been reported before. Such a high photo-to-current conversion efficiency is ascribed to the synergistic effect of energy band structure and the high reactivity of exposed (110) and (10) facets.