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

Abstract

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 μmol 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 − π * 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.