Tricycloquinazoline-containing 3D conjugated microporous polymers and 2D covalent quinazoline networks: microstructure and conductivity

Abstract

Conjugated microporous polymers (CMPs) and covalent triazine frameworks (CTFs) with conjugated linkages and nanochannels have been showcased as a new platform in extensive fields. Here, by tuning the geometry of the N-rich skeleton tricycloquinazoline (TQ) unit, isomers of the 3D amorphous conjugated microporous polymer (TQ-CMP) and 2D laminar covalent quinazoline network (TQ-CQN) are synthesized. The derived diverse microstructure and electrical conductivity related to the applications of gas adsorption and the hydrogen evolution reaction (HER) are systematically discussed. TQ-CMP fabricated with an internal crosslinking network reveals a notable uptake of 25.6 wt% CO₂ and of 2.91 wt% CH₄ at 273 K and 1 bar, higher than most reported POP materials, which could be attributed to the higher BET surface area (781.0 m² g⁻¹) and dispersed pore size (1.1 nm to 13.1 nm) for guest molecule absorption. In contrast, both the modulated electronic structure of the precise π-conjugate planes and the vertically ordered one-dimensional channels endow TQ-CQN with more built-in catalytic sites and rapid electron transmission for the HER. Without any noble metal doping, the excellent catalytic activity and faster reaction kinetics of TQ-CQN are epitomized by the achieved lower overpotential of 80 mV and the Tafel slope of 40 mV dec⁻¹. This work not only clarifies the interaction of the microstructure and conductivity of porous organic polymers for gas adsorption and the HER, but also provides flexible design guidance for future functional exploration.