BiFeO3-PDMS hybrids: Development of visible-active floating photocatalysts with minimal catalyst loading

Recent advances in photocatalysis include the development of floating catalysts since they assure efficient and rapid recollection of the catalysts from the purified liquid, besides enhancing the availability of photons at the catalytic surface. Bismuth ferrite (BiFeO3 and BFO) is a multifunctional perovskite material renowned for its excellent photocatalytic properties. Since bandgap of BFO falls in the visible spectrum, BFO nanoparticles could be combined with a suitable floating substrate to develop efficient visible light photocatalysts. Here, we report the synthesis of BFO-polydimethylsiloxane (PDMS) hybrids for photocatalytic applications, where sol-gel-synthesized BFO nanoparticles are immobilized on a floating porous PDMS sponge. The successful incorporation of the nanoparticles on PDMS is confirmed using Raman spectroscopy, scanning electron microscopy, and energy dispersive x-ray spectroscopy. The photocatalytic activity of the floating catalysts was studied by monitoring the degradation of malachite green dye under visible light irradiation. The effect of the amount of BFO immobilized, and the area and thickness of the PDMS sponge on the photocatalytic activity of the floating catalysts were investigated. An efficiency of 80.5% was obtained when the weight of BFO immobilized on the PDMS sponge was 5 mg. The method yields degradation efficiencies comparable with or higher than that of conventional BFO powder catalysts, even with 6-18 times less catalyst loading. The method introduces the fabrication of recyclable floating photocatalysts of notable efficiency using significantly less amount of BFO nanoparticles, which could be further modified by approaches such as doping, functionalization, or composite formation.