Synthesis of nitrogen vacancy-riched ultrathin polymeric carbon nitride nanosheets via ethanol-ethylene glycol ultrasonic exfoliation and photocatalytic hydrogen evolution activity

Abstract

Understanding the effects of active sites on photocatalyst surface is highly crucial in photocatalytic water-splitting hydrogen evolution. Herein, an exfoliated carbon nitride nanosheet (CNN) in two atomic layers with surface nitrogen vacancies (VNs) was used to investigate the correlation between VNs and photocatalytic hydrogen evolution activity. The few-layered CNNs were prepared via the exfoliation of block polymerized carbon nitride (PCN) with melon as the structural unit. The exfoliation was performed through an ultrasonication method assisted with ethanol and ethylene glycol mixture as the intercalation reagent. The results revealed that the formation of VNs on the peeled CNNs, accompanied with the increased content of hydroxyl. The effects of VNs on the electronic property of CNN and the water molecule adsorption are verified by the experimental results and DFT simulations. More interestingly, the photocatalytic hydrogen evolution activity of CNN was 2.14 times higher than that of PCN, which can be due to the successful introduction of VNs. This work may offer a novel insight into the effects of VNs of carbon nitride on photocatalytic hydrogen evolution.