Modified BiFeO3/rGO nanocomposite by controlled synthesis to enhance adsorption and visible-light photocatalytic activity

In this study, a sol-gel process is used to synthesize a bismuth ferrite (BiFeO3, or BFO for short)/reduced graphene oxide (rGO) nanocomposite (BGO). The structural, morphological, and optical characteristics of the BiFeO3 nanopowder are modified by controlling heat treatment parameters and rGO contents. The semi-spherical BFO nanoparticles possess rhombohedral distorted perovskite crystal structure and are grafted on rGO nanosheets of various sizes which are attributed to the existence of rGO content during the sol-gel process. The observed interface between rGO nanosheets and BFO nanoparticles assists in the efficient charge separation and transfer of photogenerated BFO charge carriers through rGO nanosheets. Compared to BFO, BGO has a narrower band gap energy of 1.8 eV, a lower rate of charge carrier recombination, and stronger magnetic characteristics. The adsorption performance and photocatalytic activity mechanisms have been thoroughly examined. By adding rGO, the adsorption isotherm of methylene blue (MB) on the BFO photocatalyst changed from the Freundlich to the Langmuir. Also, the adsorption kinetics were investigated using a pseudo-second-order model. Furthermore, the degradation of MB is used to evaluate the visible light photocatalytic activity whereby 98% degradation was reached after 300 min. The Mott-Schottky test and the active species scavenger experiment are used to assess the potential mechanisms of MB photodegradation. The findings showed that the primary active species in photodegradation were hydroxyl radicals. Also, the nanocomposite was reasonably stable, and it could be magnetically removed from aqueous environments and utilized again for subsequent usage.