Unravelling the mechanistic role of TiOC bonding bridge at titania/lignocellulosic biomass interface for Cr(VI) photoreduction under visible light.

Efficient multifunctional Titania/Lignocellulosic Biomass (TiO-OP) composite photocatalysts were fabricated via ultrasonic-assisted sol-gel for the photoreduction of Cr(VI) under UV and visible light. Materials were fully characterized using FTIR, XPS, BET, SEM-EDS, UV-DRS, XRD, photo-current and contact angle measurements. It was deduced that the produced TiOC bonding bridge between TiO clusters and olive pits lignocellulosic surface exhibits a significant role for the visible light response and band gap narrowing, wherein, E values were between 3.02 and 2.63 eV as a function of TiO/OP ratio. TiO-OP composites showed an astonishing photocatalytic efficiency, i.e., a complete reduction of Cr(VI) at 10 ppm was found within 30 min with TiO-OP(50%), against 90 min for TiO under UV light. Nevertheless, in terms of TiO-OP(50%), a total reduction was obtained within 50 min under visible light, while no photoactivity was observed with bare-TiO. Several plausible mechanistic pathways behind the photocatalytic efficiency of TiO-OP composites were discussed.