Charge transfer between biogenic jarosite derived Fe³⁺and TiO₂ enhances visible light photocatalytic activity of TiO₂

In this work, we have shown that mining waste derived Fe³⁺ can be used to enhance the photocatalytic activity of TiO₂. This will allow us to harness a waste product from the mines, and utilize it to enhance TiO₂ photocatalytic waste water treatment efficiency. An organic linker mediated route was utilized to create a composite of TiO₂ and biogenic jarosite. Evidence of FeOTi bonding in the TiO₂/jarosite composite was apparent from the FTIR, EFTEM, EELS and ELNEFS analysis. The as prepared material showed enhanced photocatalytic activity compared to pristine TiO₂, biogenic jarosite and mechanically mixed sample of jarosite and TiO₂ under both simulated and natural solar irradiation. The prepared material can reduce the electrical energy consumption by 4 times compared to pristine P25 for degradation of organic pollutant in water. The material also showed good recyclability. Results obtained from sedimentation experiments showed that the larger sized jarosite material provided the surface to TiO₂ nanoparticles, which increases the settling rate of the materials. This allowed simple and efficient recovery of the catalyst from the reaction system after completion of photocatalysis. Enhanced photocatalytic activity of the composite material was due to effective charge transfer between TiO₂ and jarosite derived Fe³⁺ as was shown from the EELS and ELNEFS. Generation of OH was supported by photoluminesence (PL) experiments.