Engineering Amino Acid Functionalized Chiral Carbon-Organic Frameworks for Enhanced Photocatalytic Hydrogen Production.

The spin-dependent recombination behavior of photogenerated charges has long been overlooked in the study of photocatalytic hydrogen (H₂) evolution over covalent organic frameworks (COFs). Moreover, correlating the structure of COFs with the spin states of photogenerated charges to enhance photocatalytic H₂ evolution performance remains a significant challenge. Herein, we present a chiral amino acid functionalization strategy to engineer chiral TpPa-1 COF for boosted photocatalytic H₂ evolution. Following systematic optimization, the chiral TpPa-1 COFs showcased a ∼5-fold enhancement in photocatalytic performance, achieving a record TOF of 9867 h⁻¹, alongside the second-highest reported AQY of 66% at 475 nm and HER of 2.54 mmol h⁻¹ among the reported state-of-the-art COF-based photocatalysts for H₂ evolution. Mechanism studies revealed that the synergistic effect between the chirality and the directional charge transfer allows efficient photo-generated charge separation. Furthermore, Chiral TpPa-1 assembled with polymeric carbon nitride (g-C₃N₄) in an S-scheme heterojunction can overcome the bottleneck in photocatalytic overall water splitting on g-C₃N₄ without oxygen evolution co-catalysts. In this work, we present a universal design strategy from a charge spin perspective to synthesize chiral photocatalysts for efficient photocatalytic performance.