Photocatalytic Hydrogen Evolution under Ambient Conditions on Polymeric Carbon Nitride/Donor‐π‐Acceptor Organic Molecule Heterostructures

Efficient solar‐to‐hydrogen (STH) energy conversion under ambient conditions (room temperature and atmospheric pressure) is important for pursuing scalable solar hydrogen generation. Modification of polymeric carbon nitride (PCN) by conjugated polymers has attracted great attention for improving photocatalytic hydrogen evolution (PHE) performance. However, the limited interfacial junction between PCN and conjugated polymers leads to a low density of free charges, resulting in unsatisfactory PHE activity. Herein, three donor‐π‐acceptor‐structured organic molecules (OMs) with different electron‐donating units (amino, N,N‐diethyl and triphenylamine) and same electron‐accepting unit (benzothiadiazole) are designed to modify PCN to enlarge the interfacial junction. The optimized PHE performance under AM 1.5G simulated sunlight and ambient conditions can maintain as high as 4.63 mmol h−1 g−1 (the highest record among all the reported PCN‐based photocatalysts to the best of the authors knowledge). The improved performance can be partially attributed to the strong visible light harvesting capability of OMs. Specifically, the triphenylamine unit in the formed type II molecule heterojunctions (MHJ) enables efficient charge separation at the interfacial junction, which prolongs the photogenerated electron lifetime for PHE. The designed MHJ photocatalysts show outstanding PHE performance under ambient conditions, which is highly promising for scalable STH conversion. Type II molecule heterojunctions (MHJ) with large interfacial junctions are obtained by integrating donor‐π‐acceptor‐structured organic molecules with polymeric carbon nitride (PCN). This MHJ delivers superior photocatalytic hydrogen evolution (PHE) performance (4.63 mmol h−1 g−1) under ambient conditions, which is the highest among all reported PCN‐based photocatalysts. The outstanding PHE performance under ambient conditions of the MHJ makes it promising for scalable solar‐to‐hydrogen conversion.