Colorful carbon nitride based composite films

Carbon nitride based photoelectrodes for solar water splitting devices have attracted tremendous attention. However, for practical applications, it is desirable to develop a kind of carbon nitride based photoelectrode with a wide range of colors for meeting the demand of aesthetic properties when the light harvesting devices are loaded on buildings. This work first presents an innovative strategy for constructing colorful carbon nitride films by adopting multiple-steps thermal vapor condensation (MSTVC) method. Different monomers and amounts are studied to tailor carbon nitride based photoelectrodes with different colors, including dark brown, iridescence, green, bluish violet, reddish brown, red, crimson, orange, dark yellow and black due to the change of the composition and the evolution of impressive surface hierarchical structure caused by the reaction between the sulfur-rich monomers and fluorine-doped titanium dioxide (FTO) layer. The colorful carbon nitride based photoelectrodes also generate satisfied photocatalytic activity, the photocurrent densities are from 13.2 to 96.2 μA cm⁻² at 1.23 V vs. RHE. We expect this work can be of interest not just for the development of carbon nitride photoelectrochemical cells, but also for the fundamental exploration and applications in electronics, photonics, sensors and displays.