Heptazine-Based Ordered-Distorted Copolymers with Enhanced Visible-Light Absorption for Photocatalytic Hydrogen Production

Graphical Mind the gap : A narrow-bandgap poly(heptazine imide) (PHI) semiconductor with ordered-distorted interface that captures solar spectrum up to 650 nm presents enhanced visible-light photocatalytic hydrogen production. The apparent quantum yield reaches 20 % for hydrogen production at 450 nm Poly(heptazine imide) (PHI), one of the attractive allotropes of polymeric carbon nitride, has recently received extensive attention in photocatalysis due to its extended conjugation for fast separation and transfer of the charges. However, pristine PHI bears an intrinsic optical absorption band edge at 460 nm, which largely restrains the visible light utilization. Herein, the narrow-bandgap PHI (N-PHI) with an ordered-distorted interface was fabricated from polycondensation of the mixture of NaSCN, cyanuric chloride, and LiCl. Results revealed that the enhanced optical absorption and the promoted separation and transfer of the charge carriers at the interface greatly improved the photocatalytic performance, which endowed N-PHI with an apparent quantum yield of 20 % for hydrogen production at 450 nm.