Organic Semiconductor g-C₃N₄ Modified TiO₂ Nanotube Arrays for Enhanced Photoelectrochemical Performance in Wastewater Treatment

g-C₃N₄ sensitized TiO₂ nanotube arrays (g-C₃N₄/TNTs) were fabricated by using a simple solid sublimation and transition (SST) method using urea as precursor. The photoelectrochemical (PEC) performances were evaluated in this work. It is proposed that the g-C₃N₄ layer can play dual roles: surface sensitization and passivation of TNTs surface trap states to inhibit charge recombination. The g-C₃N₄/TNTs exhibited significantly improved PEC performance compared with TNTs under blue light (460nm) irradiation. The g-C₃N₄/TNTs prepared from 3g urea showed the highest photocurrent density of approximately 65μA cm^-2, which is almost 10times as high as that of TNTs. Furthermore, g-C₃N₄/TNTs showed enhanced photoelectrocatalytic degradation of methylene blue (MB) under the blue light irradiation. The stable performance of degradation of MB in multicycle tests suggests that the hybrid g-C₃N₄/TNT electrode could be used as a low-cost photoelectrode material for wastewater treatment processes.