In situ preparation of g-C3N4/bismuth-based oxide nanocomposites with enhanced photocatalytic activity

Different mass percents of g-C 3 N 4 /Bi 2 O 2 CO 3 and g-C 3 N 4 /BiOCl nanocomposites with intimately contacted interfaces were synthesized in situ by mixing Bi 2 O 3 nanoparticles with melamine or guanidine hydrochloride and calcinating at 550   °C for 3   h. The fabricated nanocomposites were well-characterized by various analytical techniques. The results showed that the Bi 2 O 2 CO 3 and BiOCl nanosheets grow out from the g-C 3 N 4 bulk, producing closely contacted interfaces between the Bi oxide component and the g-C 3 N 4 component. The UV–vis diffuse reflectance spectra of g-C 3 N 4 /Bi 2 O 2 CO 3 and g-C 3 N 4 /BiOCl nanocomposites exhibited increased visible light absorption compared to g-C 3 N 4 and Bi 2 O 3 separately. Moreover, the nanocomposites showed significantly enhanced photocatalytic activity for the degradation of dibutyl phthalate and methyl orange under visible light. A proposed photocatalytic mechanism for the enhanced photoactivity of nanocomposites was investigated by scavenging experiments and fluorescent spectroscopy. The increased photocatalytic activity is mainly attributed to the effective separation and transfer of photo-induced carriers in the intimate contact between g-C 3 N 4 and Bi 2 O 2 CO 3 or BiOCl. The results showed that the different precursors of g-C 3 N 4 have a significant effect on the composite's structure; i.e., Bi 2 O 3 can react to form different bismuth-based oxides depending on the different precursors used to generate g-C 3 N 4 . This work demonstrates a convenient way to fabricate visible light responsive materials with potential for environmental remediation.