Fabrication of S-scheme TiO2/g-C3N4 nanocomposites for generation of hydrogen gas and removal of fluorescein dye

Abstract

Herein, an effective S-scheme heterojunctions were fabricated with ultrasonic aspects for effective decomposition of fluorescein dye and evolution of green hydrogen gas. Mesoporous pristine titania nanoparticles with anatase phase structure and 156 m2/g surface area were synthesized by sol-gel mechanism using pluronic solution as templating agent, however, g-C3N4 sheets generated by thermal treatment of urea at 515 °C. The a-synthesized nanocomposites embedded various compositions of g-C3N4 (1−10) wt% were synthesized by ultrasonic pathway. The properties of the specimens were recorded by HRTEM, XRD, DRS, N2-surface area measurement, PL and XPS. The experimental results reveal the noticeably reduction in sample crystallinity and intensity of PL peak with introduction of 8 wt% g-C3N4 supporting the efficient charge carriers separation. The sonicated heterojunction with 8 wt% g-C3N4 is account for decomposition of 94% of fluorescein anionic dye and production of hydrogen gas with rate 4.9 mmolg−1 h−1 which is eleven fold greater than that of pristine TiO2. The strong redox power of this heterojunction is ascribed to step S-scheme mechanism which promote the charge transportation and enhance the separation efficiency of the charge carriers. This charge migration route is established by trapping scavengers and PL experiments. The photocatalytic property of the optimum sample is still with exceptional reactivity for decomposition of anionic dye pollutant and evolution of hydrogen gas after six consecutive cycles.