Rational fabrication of a graphitic-C3N4/Sr2KNb5O15 nanorod composite with enhanced visible-light photoactivity for degradation of methylene blue and hydrogen production

Abstract

A g-C₃N₄/Sr₂KNb₅O₁₅ nanorod composite photocatalyst was simply prepared by direct growth of graphitic C₃N₄ on one-dimensional Sr₂KNb₅O₁₅ nanorods and evaluated by degradation of methylene blue (MB) and water splitting for H₂ production under visible light irradiation. By coupling g-C₃N₄ and Sr₂KNb₅O₁₅ nanorods, the nanocomposite with an optimal 77 wt% g-C₃N₄ exhibited 6.2 times higher activity for photodegradation than the bare g-C₃N₄ and the increase in H₂ production rate from an aqueous methanolic solution reached up to 12.1 fold after appropriate photodeposition of 0.03 wt% Rh cocatalysts. Furthermore, a comparative study on the preparation methods shows the photodegradation rate of the nanocomposite prepared by the direct growth method was found to be 3.4 times higher than those formed just by physical mixing. The results demonstrate the importance of the formation of proper nano-interfaces in the nanocomposite. Combined with theoretical prediction of the band structures, a possible mechanism is thus proposed including the formation of proper interfaces between g-C₃N₄ and Sr₂KNb₅O₁₅ by direct growth approachs promoting spatial separation of photoinduced electron–hole pairs.