Graphitic-carbon nitride support for the synthesis of shape-dependent ZnO and their application in visible light photocatalysts

Abstract

Shape-dependent synthesis of ZnO has been developed on the surface of g-C₃N₄ following a simple and reproducible strategy. Initially, graphitic-carbon nitride (g-C₃N₄) was synthesized by pyrolysis of urea which was further used to grow ZnO nanostructures via refluxing conditions. Different hydrolyzing agents, such as hexamethylenetetramine (HMT) and ammonia were used to synthesize dumbbell and cone structures, respectively. Apart from hydrolyzing agents, cetyltrimethylammoniumbromide (CTAB) was also used as a growth controlling agent. Structural, morphological and optical characterizations of the as-synthesized materials were performed by using FESEM, TEM, XRD, XPS, UV-vis etc. techniques. After successful synthesis, the as-synthesized heterostructures were explored as visible light driven photocatalysts towards organic pollutant (methylene blue and phenol) degradation. The photocatalytic performances of bare ZnO, dumbbell and cone structures of g-C₃N₄/ZnO as well as g-C₃N₄, have been examined thoroughly. Photocatalytic results revealed that g-C₃N₄/ZnO heterostructures exhibit a higher efficiency under the illumination of visible light as compared to pure g-C₃N₄. Superior photodegradation activity of the g-C₃N₄/ZnO heterostructure originated from the synergistic effect and high charge separation at the interface of g-C₃N₄ and ZnO has also been discussed.