Poly(heptazine imide) with enlarged interlayers spacing for efficient photocatalytic NO decomposition

Sluggish charge kinetics and NO diffusion largely restrict the photocatalytic efficiency of low-dose NO removal by layered carbon nitride (CN). Herein, a novel poly(heptazine imide)-based CN (CN-NaLi) with enlarged interlayer spacing was fabricated by an easy, efficient and unique molten-salt approach. The charge flows induced by the poly(heptazine imide) structure can be delocalized/separated/transferred, resulting in a significantly boosted efficiency of charge kinetics. The enlarged interlayers distance of CN-NaLi reduced the charge-recombination probability and promoted NO diffusion/adsorption/activation. Accordingly, abundant separated light-induced electrons can be supplied to react and activate the O₂ molecules. Meanwhile, large amounts of adsorbed NO were fixed and converted into the intermediate product during the same time compared with unmodified CN. The reduced energy barrier endowed CN-NaLi with superior visible-light-driven performance, high stability, and decreased generation of toxic products in NO purification. This research highlighted the vital concerns in affecting the interlayer NO diffusion/adsorption/activation and charge delocalization/separation/transportation. Copyright © 2022 Elsevier B.V. All rights reserved.