Spatially Separated Redox Cocatalysts on Poly Triazine Imides Boosting Photocatalytic Overall Water Splitting

Abstract Poly (triazine imide) (PTI), a crystalline allotrope of polymeric carbon nitride, holds great promise for photocatalytic overall water splitting (OWS). However, previous results reveal that both H₂ and O₂ evolution cocatalysts prefer to deposit on the prismatic facets, which results in the undesired backward reaction and current unsatisfied quantum efficiency for OWS reaction. Herein, in situ decoration with heptazine based carbon nitride (HCN) at the interface of PTI is successfully employed to construct S‐scheme hetero‐phase junctions. The built‐in electric field at the interface of PTI and HCN endows directed carrier separation, thereby enabling the separation of redox sites, as validated by theoretical and experimental results. Accordingly, the as‐synthesized PTI/HCN with spatially separated charge carriers and restrained backward reaction achieves a solar‐to‐hydrogen energy conversion efficiency of 0.35% for photocatalytic OWS reaction.