Noble metal-free g-C3N4/TiO2/CNT ternary nanocomposite with enhanced photocatalytic performance under visible-light irradiation via multi-step charge transfer process

The excellent visible light photocatalytic activity and stability of g-C3N4/TiO2/CNT ternary nanocomposite photocatalysts was mainly attributed to the multistep transfer of electrons by heterojunction formation at g-C3N4/TiO2 interface and CNT. [Display omitted] •Noble metal-free g-C3N4/TiO2/CNT ternary nanocomposites were prepared by a facile hydrothermal method.•Ternary nanocomposite showed enhanced visible-light absorption.•Heterojunction formation and synergistic effect of CNT account for the enhanced photocatalytic performance.•The electrons and OH are the main photoactive species responsible for the decolouration of MB.•The g-C3N4/TiO2/CNT ternary nanocomposite exhibited excellent photo stability. A noble metal-free photocatalyst, consisting of graphitic carbon nitride (g-C3N4), TiO2 and carbon nanotubes (CNT) was synthesized by a facile hydrothermal method and its application for the photocatalytic decolouration of methylene blue (MB) dye under visible light irradiation has been demonstrated. The microstructure, morphology, structural and optical properties of the synthesized nanocomposites was systematically studied using TEM, SEM, XRD, RAMAN, FTIR and UV–Vis DRS techniques. The g-C3N4/TiO2/CNT ternary nanocomposite exhibits five times higher photocatalytic activity compared to bare g-C3N4 under visible light irradiation. Enhanced photocatalytic performance of the ternary nanocomposite has been attributed to the synergistic effects of three components: Multistep charge transfer between heterojunction formation at g-C3N4/TiO2 interface and CNT, enhanced visible-light absorption and effective charge separation. A possible reaction mechanism has been proposed and scavenger experiment has been carried out to find the role of active radical species responsible for the dye decolouration. Additionally, the g-C3N4/TiO2/CNT photocatalyst retained excellent stability even after several cycles. This study offers a promising way of developing a highly efficient, noble metal-free, stable and visible-light-driven photocatalyst to promote the utilization of solar energy for environmental purification.