Extending Conjugation Lengths of the Linkage Units in Triazine-Based Porous Polymers for Enhanced Photocatalysis

Three triazine-based conjugated porous polymers (CPPs) are synthesized via a Pd-catalyzed Suzuki-Miyaura coupling reaction between derivatives of 2,4,6-tri(thiophen-2-yl)-1,3,5-triazine (TTT) and 2,4,6-triphenyl-1,3,5-triazine (TPT). Photocatalysis experiments demonstrate that the hydrogen evolution rate (HER) of ThTh-CPP (homopolymer of TTT) reach an exceptional 46.4 mmol g⁻¹ h⁻¹ without co-catalysts, surpassing ThPh-CPP (8.26 mmol g⁻¹ h⁻¹, a copolymer of TTT and TPT) and PhPh-CPP (3.06 mmol g⁻¹ h⁻¹, homopolymer of TPT), as well as nearly all similar polymer-based catalysts reported to date, under visible light. The variance in photocatalytic activity is attributed to differences in the linkage units on the triazine ring. Mechanistic analysis, combining experimental and theoretical studies, highlights the potential of engineering the electron-donating ability of the linkage units to enhance photocatalytic hydrogen evolution in triazine-based conjugated polymers.