Ion-Induced Synthesis of Crystalline Carbon Nitride Ultrathin Nanosheets from Mesoporous Melon for Efficient Photocatalytic Hydrogen Evolution with Synchronous Highly Selective Oxidation of Benzyl Alcohol

Crystalline carbon nitride (CCN) with a poly(heptazine imide) structure is efficient in photocatalytic hydrogen evolution (PHE), but synthesis of CCN ultrathin nanosheets (CCNuns) and their use in PHE with selective organic oxidation are still rare. Herein, CCNuns with Na+ doping are prepared using NaCl as the ion-induction and templating agent and mesoporous melon as the feedstock, exhibiting efficient synchronous PHE and benzyl alcohol oxidation to benzaldehyde, with an apparent quantum yield of 10.5% at 420 nm and a visible light PHE rate that is 94.3 times that of bulk polymeric carbon nitride (PCN). The selectivity of benzaldehyde formation (90.5%) is also much higher than that of PCN (40.7%). Interestingly, this selectivity increases gradually with increasing light wavelengths. The high photoactivity of CCNuns originates from their ultrathinness and Na+ doping, which considerably enhance the photogenerated charge separation. This work opens up an avenue for the synthesis of CCNuns and extends their application.

Automated summary

In this study, Na+-doped ultrathin crystalline carbon nitride nanosheets (CCNuns) were successfully synthesized and demonstrated high performance in photocatalytic hydrogen evolution and organic oxidation. Additionally, the selectivity of CCNuns for benzaldehyde formation was found to increase gradually with increasing light wavelengths, which is of great significance.