Molecular Self-Assembly of Oxygen Deep-Doped Ultrathin C3N4 with a Built-In Electric Field for Efficient Photocatalytic H2 Evolution

Heteroatom-doped carbon nitride (C3N4) with a built-in electric field can reinforce the carrier separation; however, the stability will be greatly reduced due to the loss of surface-doped atoms. Here, molecule self-assembly, as a facile bottom-up approach, is explored for the synthesis and oxygen doping of C3N4. The obtained C3N4 presents a porous and ultrathin structure and oxygen deep-doping, which generate abundant nitrogen vacancies and a stable built-in electric field. Toward photocatalytic hydrogen evolution, the ultrathin and oxygen deep-doped C3N4 exhibits a 3.5-fold higher activity than bulk C3N4 under simulated sunlight, and 3.6 times higher stability than the oxygen surface-doped counterpart within five cycles. Femtosecond transient absorption spectroscopy indicates the improved carrier separation, and density functional theory (DFT) calculation reveals the promoted H2O adsorption and activation under the built-in electric field, which contribute to the excellent photocatalytic performance of oxygen deep-doped ultrathin C3N4.

Automated summary

In this study, oxygen-doped ultrathin C3N4 was successfully synthesized through molecule self-assembly. The material exhibited excellent photocatalytic performance for hydrogen evolution, with enhanced activity and stability compared to bulk C3N4. The improved carrier separation and promoted H2O adsorption and activation under the built-in electric field contribute to its outstanding performance.