β-ketoenamine-modified covalent triazine frameworks with extended visible-light absorption for efficient photocatalytic water splitting

β-Ketoenamine TpABN is incorporated into CTF-1 via eutectic-salt ionothermal synthesis. • The strategy repairs surface defects, suppresses carbonization, and extends absorption to ∼700 nm. • The keto–triazine donor–acceptor structure promotes charge transfer and carrier lifetime. • CTF-TpABN achieves 3485 ± 64 μmol g −1  h −1 visible-light H 2 evolution. • CTF-TpABN shows 4- or 27-fold higher H 2 evolution and improved O 2 evolution than CTF-MS or CTF-TfOH. Covalent triazine frameworks (CTFs) are promising photocatalysts for water splitting, but weak visible-light absorption and inefficient charge separation caused by intrinsic structural constraints limit their activity. Herein, a β-ketoenamine-based molecule, TpABN, is incorporated into the CTF-1 backbone via low-temperature ionothermal synthesis employing a ZnCl 2 –NaCl–KCl ternary eutectic salt-catalyzed method. This strategy repairs surface defects, suppresses carbonization, and extends the optical absorption edge to ∼700 nm. The resulting keto–triazine donor–acceptor architecture promotes intramolecular charge transfer and prolongs the excited-state carrier lifetime. Consequently, CTF-TpABN achieves a 4-fold higher photocatalytic H 2 evolution rate(3485 ± 64 μmol/g/h) than CTF-MS (without β-ketoenamine modification) and a 27-fold higher rate than CTF-TfOH (synthesized via TfOH catalysis) under visible light (λ > 400 nm, 3 wt% Pt cocatalyst, 10 vol% TEOA). It also shows improved visible-light O 2 evolution (λ > 400 nm, 2 wt% RuO x cocatalyst, 0.05 M AgNO 3 ). These findings highlight CTF-TpABN as a promising visible-light-driven water-splitting photocatalyst and guide CTF-based photocatalyst design. A β-ketoenamine-based molecule (TpABN) is integrated into CTF-1 via a ternary eutectic salt-catalyzed ionothermal method to enhance visible-light absorption and charge separation. The resulting CTF-TpABN shows suppressed carbonization, extended absorption to ∼700 nm, and 27-fold improved H 2 evolution. This study offers insights into designing efficient photocatalysts for visible-light-driven water splitting. Download: Download high-res image (228KB) Download: Download full-size image