This paper reports a general synthesis of carbon nitride (CN) films with extended optical absorption, excellent charge separation under illumination, and outstanding performance as a photoanode in water-splitting photoelectrochemical cells. A universal method rapidly grows CN monomers directly from a hot saturated solution on various substrates. Calcination yields a uniform carbon nitride layer with tuned properties and intimate substrate contact. The best CN photoanode shows a photocurrent density of 353 µA cm⁻² (51% faradaic efficiency for oxygen) and an external quantum yield above 12% at 450 nm at 1.23 V versus RHE in an alkaline solution.

Jiani Qin, Jesús Barrio, Guiming Peng, Jonathan Tzadikov, Liel Abisdris, Michael Volokh, Menny Shalom