Phosphorus‐doped Isotype g‐C 3 N 4 /g‐C 3 N 4 : An Efficient Charge Transfer System for Photoelectrochemical Water Oxidation

Constructing isotype g‐C 3 N 4 /g‐C 3 N 4 heterojunction is an approach to improve the efficiency of g‐C 3 N 4 towards solar‐assisted oxidation of water. Such functional configuration can effectively overcome the intrinsic drawback of rapid charge recombination of g‐C 3 N 4 . Here, a modified g‐C 3 N 4 , with homogeneous phosphorus doping, is prepared in this work through a phosphide‐involved gas phase reaction. The resulting P‐g‐C 3 N 4 displays altered electronic structure, including upshifted band edge potential, narrowed band gap and improved electronic conductivity. These features allow P‐g‐C 3 N 4 as an outstanding candidate to form isotype junction with pristine g‐C 3 N 4 . As expected, the accelerated charge separation and migration in target junction is validated by various measurements. The optimized isotype g‐C 3 N 4 /P‐g‐C 3 N 4 heterojunction achieves a photocurrent as high as 0.3 mA cm −2 at 1.23 V vs RHE (AM 1.5G, 100 mW cm −2 ), representing 8‐fold's enhancement compared with pristine g‐C 3 N 4 . The present strategy for constructing g‐C 3 N 4 ‐based isotype heterojunction networks is found effective for large‐scale manufacturing.