A pyrrolo[3,2-b]pyrrole core containing a covalent triazine-based framework (CTF) for photocatalytic H2 production

Abstract

The pursuit of developing photocatalysts for visible-light-driven water splitting has garnered considerable attention within the research community. In this context, covalent triazine-based frameworks (CTFs) have emerged as the most important materials in the realm of photocatalytic water splitting owing to their predictive structural design, well-defined long-range ordering, tunable porosity, and remarkable stability. In this study, we present a pyrrolo[3,2-b]pyrrole core-containing CTF, named CTF-TPP, which was fabricated from 1,2,4,5-tetrakis(4-cyanophenyl)-1,4-dihydropyrrolo[3,2-b]pyrrole (TPP) by a solvothermal method. This synthesized CTF-TPP served as a dye-sensitized photocatalyst for visible light-induced water splitting that exhibits H₂ production of 612 μmol g⁻¹ in 4 h. In addition, the hydrogen evolution rate (HER) was enhanced by introducing in situ generated Pt and Pd nanoparticles (NPs) into the CTF-TPP solid matrix in different proportions. Among them, CTF-TPP@Pd_0.5 exhibited superior H₂ evolution compared to its Pt counterpart, achieving a hydrogen production rate of 7980 μmol g⁻¹ in 4 h with an apparent quantum efficiency (AQY) of 13.97% at 420 nm. Additionally, it demonstrated a good turnover number (TON) exceeding 173 for 4 h of photocatalysis. This enhanced performance was attributed to the strong interaction between the Pd NPs and CTF-TPP, facilitating efficient photoelectron transfer. Furthermore, we have also given a plausible mechanism based on the photophysical and electrochemical study to efficiently elucidate the enhanced photocatalytic H₂ production. This study offers an idea for developing a highly efficient photocatalyst based on CTF in the context of H₂ production.