Bio-inspired honeycomb-like graphitic carbon nitride for enhanced visible light photocatalytic CO2 reduction activity

Graphitic carbon nitride (g-C3N4) is paying attention lately owing to its interesting characteristics and substantial application in improving environmental and energy concerns. Nevertheless, the photocatalytic activity of g-C3N4 is constrained by the inertness of the surface and particle aggregation during photocatalytic activity. Herein, we report the preparation of g-C3N4 with honeycomb-like morphology (HC-C3N4) via thermal condensation of prepared SiO2 templates and dicyandiamide. The etching out of the SiO2 templates by NH4HF2 created hollow or macropores in the C3N4 matrix resulting in its structural changes. Similar, to the bulk C3N4, the HC-C3N4 exhibited higher photocatalytic CO2 reduction in hydrocarbons. This improved photocatalytic achievement is associated with higher specific surface area, excellent visible light absorption capability, higher electron donor density, easy mass diffusion of materials for surface reaction, and effective segregation of photogenerated charge carriers. Furthermore, the HC-C3N4 honeycomb structure was deposited with Ni(OH)2 clusters which showed remarkable CO2 reduction activity of 1.48 μmolh−1 g−1 of CH4 and 0.73 μmolh−1 g−1 of CH3OH generation which is 3.5 and 4.3 times higher CO2 reduction activity compared with bulk C3N4 clustered with Ni(OH)2 particles. This comprehensive study demonstrated that HC-C3N4 nanostructured polymeric semiconductor is envisaged to have great potential in the application of a variety of fields such as photocatalysis, sensor technology, and nanotechnology.