Visible-Light-Induced Graphitic-C3N4@Nickel-Aluminum Layered Double Hydroxide Nanocomposites with Enhanced Photocatalytic Activity for Removal of Dyes in Water.

One of the major challenges in photodegradation of organic dyes is designing a visible light active and highly efficient photocatalyst that can degrade both cationic and anionic dyes. To design such an ideal catalyst, this work synthesized graphitic-C3N4@NiAl layered double hydroxide nanocomposites (g-C3N4@NiAl-LDH NCPs) with various g-C3N4 contents through a convenient and high-yield method. The photocatalytic process was optimized by evaluating the impacts of type of dye (cationic and anionic), photocatalyst dosage, pH, and contact time. According to the results, the photocatalytic performance of g-C3N4@NiAl-LDH NCPs in degradation of cationic and anionic dyes is more noticeable than the photocatalytic activities of its discrete components. The observed improvement in the photocatalytic performance of the g-C3N4@NiAl-LDH NCPs can be attributed to the intimacy of their contact interfaces and a synergistic effect between pristine g-C3N4 and NiAl-LDH, which results in effective mass transfer and separation of photogenerated charge carriers. The impact of some charge scavengers on the process was evaluated to define the role of each active species and propose a possible photodegradation mechanism. The g-C3N4@Ni-Al LDH NCPs could be reused for four cycles without any significant loss in efficiency.