Engineering Amorphous Carbon onto Ultrathin g‐C 3 N 4 to Suppress Intersystem Crossing for Efficient Photocatalytic H 2 Evolution

Tuning photochemistry conversion efficiency by atomic‐level tailoring will unlock great potential for pursuing higher photocatalytic performance for graphitic carbon nitride (g‐C 3 N 4 ). Here, a novel strategy to fabricate amorphous carbon–engineered ultrathin g‐C 3 N 4 nanocomposites, endowing the engineered g‐C 3 N 4 with a much higher H 2 evolution rate, reaching an optimum value as high as 746.95 µmol h −1 g −1 , 15.4 times higher than that of bulk g‐C 3 N 4 , is described. Interestingly, with the formation of intimate interfaces between amorphous carbon and ultrathin g‐C 3 N 4 , the interfacial charge transfer is boosted significantly and the recombination rate of photogenerated electrons and holes could be highly reduced, thus leading to a higher quantum yield. Moreover, the thickness of the g‐C 3 N 4 is significantly reduced by the steric‐hindrance effect of amorphous carbon grown in situ, and the as‐prepared ultrathin g‐C 3 N 4 shows a suppressed intersystem crossing rate in the photocatalytic H 2 evolution process, thus leading to a lower triplet exciton concentration in the energy conversion process, and also faint triplet–triplet annihilation. It is believed that the present work identifies a new pathway to understanding the role of carbon in nanostructure construction, and will be of broad interest in research on engineering metal‐free carbon‐based catalysts and on solar conversion systems.