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‐C3N4) 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‐C3N4 composite is designed by stitching NGQDs with g‐C3N4 through a thermal condensation approach, which conjugate via NGQDs‐lone pair electrons in a ternary N‐g‐C3N4 nanosheet (π–p–π) network. It is found that the H2 evolution rate under visible light (λ ≥ 420 nm) irradiation with NGQDs/g‐C3N4 is nearly 7.7, 7.2, and 2.5 times higher than that of pristine g‐C3N4, the mixture of NGQD and g‐C3N4, and a non‐nitrogen‐doped GQDs/g‐C3N4 composite, respectively. Due to better light harvesting in the NGQDs/g‐C3N4 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‐C3N4 generates new bands, driving the charge transfer along the π–p–π network and extending the visible light response range.