Highly intra- and inter-plane crystalline ReSx/g-C3N4: Facile synthesis and boosted photocatalytic H2 evolution

Abstract

Improving the crystallinity of g-C3N4 is regarded as a desirable pathway to boost its photocatalytic activity. However, the current highly crystalline g-C3N4 photocatalysts are mainly emphasized on increasing their inter-plane crystallinity through ordered stacking layers while their intra-plane crystallinity has been seldomly concerned, causing the finitely enhanced photocatalytic performance. In this work, the high intra- and inter-plane crystallinity of g-C3N4 accompanied by the deposition of amorphous ReSx cocatalyst are simultaneously realized through a facile strategy, causing the successful formation of highly intra- and inter-plane crystalline ReSx/g-C3N4 (ReSx/c-CN) photocatalysts. In this case, the mixture of melamine and NaCl is initially calcined to prepare highly intra-plane crystalline g-C3N4 (i-CN). Subsequently, the i-CN is further treated by HCl to improve its inter-plane crystallinity, which can simultaneously realize the deposition of amorphous ReSx cocatalyst on g-C3N4 surface to finally produce ReSx/c-CN photocatalysts. Consequently, the high intra- and inter-plane crystallinity of g-C3N4 can effectively boost the separation and migration of photogenerated carriers, while the amorphous ReSx cocatalyst can supply abundant active sites for interfacial H2-evolution reaction. Thus, the optimized ReSx/c-CN(3.0 wt%) photocatalyst exhibit remarkably improved H2-generation activity (23.4 μmol h−1), which is about 8.4-fold of the ReSx/bulk g-C3N4(3.0 wt%) photocatalyst. This work may supply new ideas for exploring other highly efficient photocatalysts in various applications.