Vapor deposition of g-C3N4 on TiO2 nanosquares for efficient photodegradation of MB and Cr6+ under visible light

Herein, a novel composite photocatalyst was prepared by the vapor deposition of g-C3N4 on TiO2 nanosquare, dominated with {001} facets. The deposition method is robust, convenient, and effective. The surface topography and structure of the composites were analyzed by XRD, XPS, SEM, and TEM. The mechanism for enhanced photocatalysis was studied using PL, PC, UV-vis-NIR-DRS, TRPL, EIS and EPR. The photocatalytic activities of the fabricated composites were evaluated by the degradation of methylene blue (MB) and hexavalent chromium ions (Cr6+) under visible light irradiation. The photodegradation of MB and Cr6+ was completed in 50 and 40 min, respectively. Based on a pseudo-first-order kinetic model (ln(C-0/C) = kt), the measured the degradation rate constant for MB using gCN/TO5 was 4.6 and 35.9 times higher than that of pure g-C3N4 and TiO2, respectively. Similar results were found for the Cr6+ degradation. The outstanding photocatalytic performance of the g-C3N4 on TiO2 composite was ascribed to the presence of the TiO2/g-C3N4 heterojunctions, which effectively improved the separation of the photoexcited electrons and holes hence the enhancement of visible-light photoactivity. Overall, this work showed a convenient and efficient method for fabricating the visible light photocatalysts with established possible mechanisms for the photoactivity of the hybrid photocatalytic composite material.