Chemical Interaction in Nitrogen‐Doped Graphene Quantum Dots/Graphitic Carbon Nitride Heterostructures with Enhanced Photocatalytic H₂ Evolution

Abstract

Strong electronic coupling between graphene quantum dots (GQDs) and graphitic carbon nitride (g‐C 3 N 4 ) enables multiple charge transfer pathways, offers a new approach for light harvesting, and opens novel applications for carbon‐based materials. Herein, a nitrogen‐doped graphene quantum dots (NGQDs)/g‐C 3 N 4 composite is designed by stitching NGQDs with g‐C 3 N 4 through a thermal condensation approach, which conjugate via NGQDs‐lone pair electrons in a ternary N‐g‐C 3 N 4 nanosheet (π–p–π) network. It is found that the H 2 evolution rate under visible light ( λ ≥ 420 nm) irradiation with NGQDs/g‐C 3 N 4 is nearly 7.7, 7.2, and 2.5 times higher than that of pristine g‐C 3 N 4 , the mixture of NGQD and g‐C 3 N 4 , and a non‐nitrogen‐doped GQDs/g‐C 3 N 4 composite, respectively. Due to better light harvesting in the NGQDs/g‐C 3 N 4 composite, higher photocatalytic activities are also observed compared to others when they are illuminated by 520 and 550 nm light. It is demonstrated that the electronic coupling between NGQDs and g‐C 3 N 4 generates new bands, driving the charge transfer along the π–p–π network and extending the visible light response range.