Simultaneously improve the delocalization of π electrons and directional transfer of charge carriers in carbon nitride for superior photocatalytic hydrogen evolution

Abstract

Photocatalytic water splitting represents a green and promising strategy for hydrogen production. However, the slow charge carrier dynamics in polymeric carbon nitride (PCN) limits its photocatalytic efficiency. Herein, 1,4-dicarboxybenzene is incorporated into the edge of PCN skeleton (PCN-2AA-3) via a pyrolysis-copolymerization strategy. This modification not only expands the π-conjugated electron mobility domain but also introduces an electron-withdrawing functional group in PCN. Consequently, the cooperative effect accelerates charge separation, and facilitates directional migration, resulting in the improved photocatalytic hydrogen evolution performance. Compared to pristine PCN, PCN-2AA-3 exhibits a threefold increase in hydrogen evolution rate, reaching 1692.1 µmol g-1 h-1 with an apparent quantum efficiency (AQE) of 16.4% at 420 nm. Density functional theory (DFT) calculations confirm the existence of spatial separation of HOMO and LUMO. Barder charge analysis demonstrates the accumulation domain of electrons. Furthermore, the preferential deposition of Pt nanoparticles on the edges of PCN-2AA-3 nanosheets validates the effective directional migration of electrons. This work offers a straightforward approach to fabricate a high-performance photocatalyst for advanced applications.