Doping Engineering in Polymeric Carbon Nitride for Low‐Onset‐Potential Photoelectrochemical Applications.

As a metal‐free semiconductor photoelectrode material, polymeric carbon nitride (CN) has become one of the research hotspots in the field of photoelectrochemical (PEC) water splitting due to its unique physical and chemical properties. However, high onset potential (Vonset) seriously hinders PEC properties and utilization of solar energy. Herein, boron or phosphor‐doped polymeric carbon nitride (CN−B/P) films are successfully prepared by combining close‐spaced thermal copolymerization with a simple drip coating‐heat treatment method. As a photoanode material, the as‐synthesized doped‐CN films exhibit excellent performance with improved charge injection properties, a longer electron lifetime and reduced flat band potential. Consequently, the photocurrent density of CN−B/P is increased by about 1–3 times compared with pure carbon nitride samples. More importantly, the CN−B and CN−P photoanode both exhibit a very negative Vonset of about 0 V versus reversible hydrogen electrode, which is comparable with the state‐of‐the‐art metal‐based photoanodes. [ABSTRACT FROM AUTHOR]