Enhanced Photoelectrochemical Performance of g-C3N4/tiO2 Heterostructure by the Cooperation of Oxygen Vacancy and Protonation Treatment

Abstract

A g-C3N4/TiO2 (CN/TiO2) nanocomposite was fabricated by depositing proton-functionalized g-C3N4 nanosheets onto the TiO2 nanotube array films with oxygen vacancies. Proton-functionalized g-C3N4 (p-CN) nanosheets was prepared by sonication-exfoliation of bulk g-C3N4 in the presence of hydrochloric acid. Protonation pretreatment of g-C3N4 reduce the size of g-C3N4 and increase the interfacial contact area of g-C3N4 nanosheets with TiO2 nanotube arrays. TiO2 nanotube arrays containing oxygen vacancy (OV-TiO2) was obtained by NaBH4 reduction, which results in the enhanced visible light absorption. As a result, the best photocurrent density of p-CN/OV-TiO2 nanocomposite is 5.3 times higher than that of CN/TiO2 samples. As further confirmed by photocatalytic degradation of methyl orange (MO), p-CN/OV-TiO2 heterostructure exhibit the highest photocatalytic activity among all the prepared samples. This improved photoelectrochemical (PEC) and photocatalytic performance can be attributed to the formation of a direct Z-Scheme heterostructure between protonated g-C3N4 and TiO2 containing oxygen vacancy.