On an iridescent film of carbon nitride grown on an aluminum sheet and composed of overlapped oak-leaf shaped nanoparticles

An iridescent carbon nitrogen film g-C3N4 was formed by chemical vapor deposition (CVD) on an aluminum sheet starting from melamine cyanurate as a precursor at a temperature of 600 °C. The film was easily detached and thoroughly characterized using various techniques, including X-ray powder diffraction, UV − Vis and infrared spectroscopies, and field emission scanning microscopy. The material exhibited a particular layered microstructure consisting of stacks of nano-/micro-sized oak-leaf-shaped particles. The UV − Vis spectrum exhibited two defined bands corresponding to localized electrons; however, the apparent direct bandgap was 3.1 eV, similar to that of bulk g-C3N4. The IR spectrum was similar to that of bulk material, with differences in band intensities of the bending zone of tri-s-triazine units, in the range of 900 − 800 cm−1. The 2 D unfolding of the material with the formation of a thin layer composed of oak-leaf-like particles led to structural iridescent colors. For this reason, applications in optoelectronics and photovoltaic cells based on thin films prepared by the reported synthesis route may be envisaged, taking advantage of the properties of structural colors.