Synthesis of Polymeric Carbon Nitride Films with Adhesive Interfaces for Solar Water Splitting Devices

Abstract

Polymeric carbon nitride (PCN) films are synthesized for solar water splitting devices. Herein, five precursors and their mixtures are attempted, achieving PCN films in ca. 40 different morphologies. We find that sulfur (S) containing and non-S precursors must be mixed to grow PCN films on fluorine doped tin oxide (FTO) glasses. Through the investigations of the PCN films, S is found to only exist at the interfaces between the PCN and FTO films. In this case, S acts not only as the initialization for the growth of the PCN films but also as connections to assist charge migration for water splitting devices. As a result, the best performance ca. 100 μA/cm2 is achieved at 1.23 VRHE under AM 1.5 illumination in NaOH electrolyte solution without sacrificial agent. This result can be attributed to the reduced defects along the interfaces and the lessened charge recombination. This synthesis of PCN films with the improved chemical adhesion to the FTO layer envisages such organic material for the construction of other flexible functional devices.