Sulfur-doped triazine-conjugated microporous polymers for achieving the robust visible-light-driven hydrogen evolution

Conjugated microporous polymers (CMPs) have emerged in recent years as prospective materials for photocatalytic hydrogen production. The most common synthesis method for triazine is ionothermal synthesis at high temperatures (>350 °C), which also requires a large amount of ZnCl₂, in which CF₃SO₃H-catalyzed method was invented to synthesize triphenyl triazine at room temperature. Herein, we reported the synthesis and characterization of two triazine-based conjugated micropores polymers photocatalysts at low temperature via polymerization of triphenyl triazine (TPT) with TPT and pyrene (Py). The TPT-based CMPs show excellent photocatalytic performance and a hydrogen evolution rate of 108.1 and 116.5 µmol h⁻¹ under visible light for Py-TPT-CMP and TPT-TPT-CMP, respectively, but with low photocatalytic stability. In general, organic polymers add a small amount of platinum to efficiently produce H₂ with high photocatalyst stability. To provide a new opportunity to overcome the low stability, a sulfur doping method using readily available sulfur (S8) has been proposed which was used here for the first time to achieve a highly photocatalyst stability development without the use of noble metals. The as-synthesized polymers after sulfur doped exhibit an enhanced photocatalytic stability which can keep the hydrogen production for a long period of time without loss in the photocatalytic efficiency. Furthermore, our triazine-based CMP materials have interest apparent quantum yield (AQY) values particularly for Py-TPT-CMP and TPT-TPT-CMP which exhibit AQY of 41.9 and 32.38%, respectively at 420 nm, these values are compatible with the highest AQY of organic photocatalysts up to date. This study makes a significant contribution forward for photocatalysis with polymers because it provides excellent HERs and AQYs for the sulfur-doped triazine-based CMPs with high thermal, chemical, and photo stabilities. As well as, this work could give researchers in the field a different opinion on the effect of sulfur-doping.