Biogenic synthesis of mesoporous N–S–C tri-doped TiO2 photocatalyst via ultrasonic-assisted derivatization of biotemplate from expired egg white protein

Abstract The development of sustainable photocatalysts and their efficient utilization of solar light is one of key topics for addressing the current and future environmental remediation concerns. Herein, we report an ultrasonic-assisted green synthesis of mesoporous titanium dioxide (m-TiO2) nanoparticles (NPs) using an egg white protein (EWP) biotemplate derived from expired eggs, hereafter referred to as EWP-TiO2 NPs. The EWP biotemplate played multiple roles, such as source of nonmetallic elements (N, S, and C), structure-directing agent, and self-solvent, consequently bestowing excellent features on TiO2 photocatalyst. X-ray Diffraction, BET surface area, and X-ray photoelectron spectroscopy analyses indicated that the synthesized NPs have anatase phase of m-TiO2 NPs with Tri-N-S-C doping. The spherical EWP-TiO2 NPs exhibited a substantial decrease of the particle size as compared to EWP-free analogue (so-called bare TiO2 NPs). The photocatalytic activities of as-prepared TiO2 samples were evaluated by degrading Rhodamine B under simulated solar light (100 mW/cm2). The EWP-TiO2 NPs exhibited the two-fold higher photocatalytic activity than that of bare TiO2, owing to enlarged surface area, red-shift in the optical absorption band, and efficient charge separation. The biotemplate derivatization is a very effective strategy for fabricating mesoporous semiconductor doped with nonmetallic elements.