Linker functionalized poly(heptazine imide) as charge channel and activation site for enhancing photocatalytic nitrogen fixation in pure water

Poly(heptazine imide) as a metal-free semiconductor has stimulated considerable focus in the photocatalytic nitrogen fixation. However, the weak visible light absorption and unordered migration of photogenerated carriers as well as limited active site often resulted in poor photocatalytic performance. Here, we propose a conceptual to construct directional electron delivery channel via introducing C-N and N-C-O units linked terminal melem units (PCON) using a facile copolymerizing method. The optimized PCON achieved excellent photocatalytic nitrogen fixation rate (49.11 mu mol g(-1) h(-1)) and near-IR yield in pure water without using cocatalyst, which is 11 times higher than that of pristine C3N4. Based on DFT calculation and experiment results, the superior photocatalytic performance is traced back to the integrated different linker into the framework induced n - pi * transitions and acted as charge channel and activation site, which could significantly extend light absorption to the near IR, and enhance charge separation as well as reactive activation. This study lay out the importance of linker engineer of the catalyst to regulate photocatalytic activity over organic-based photocatalysts.

Automated summary

The new copolymer PCON showed significantly improved photocatalytic nitrogen fixation performance, surpassing the efficiency of pristine C3N4 by a factor of 11, without the need for additional cocatalysts. The enhanced performance is attributed to the introduction of new linker units inducing transitions and acting as charge channels and active sites, extending light absorption to near-infrared and improving charge separation and reactive activation. This study highlights the importance of linker engineering in catalyzing photocatalytic reactions using organic-based catalysts.