Donor-acceptor type triazine-based conjugated porous polymer for visible-light-driven photocatalytic hydrogen evolution.

A triazine-based conjugated microporous polymer with ideal optical band gap, which was designed and synthesized through a simple, efficient, metal-free catalyzed approach, has been demonstrated to exhibit good performance for photocatalytic visible-light driven hydrogen generation. • A novel metal-free approach was used to synthesize conjugated microporous polymer. • Band gap is narrowed through introduction of rationally designed D A type monomer. • Rich nitrogen atoms and porous morphology help to improve the photocatalytic property. • This polymer exhibits a high H 2 evolution rate under visible light illumination. Conjugated microporous polymers (CMPs) are an emerging class of promising photocatalysts because of their large specific surface areas and adjustable optical band gaps. To avoid the metal contamination, metal-free synthetic procedure for making CMPs for photocatalytic water splitting are highly desired. Herein, we designed and synthesized two triazine-based conjugated microporous polymers P1 and P2 through a simple, efficient, metal-free catalyzed approach. Through linking donor-acceptor (D-A) type pyrazole-benzothiadiazole-pyrazole light-absorbing units by triazine units, P1 has an ideal optical band gap of about 2.3 eV and exhibits a high H 2 evolution rate (HER) of 50 μmol h−1 under visible light illumination (λ ≥ 420 nm) and apparent quantum efficiency (AQE) as high as 3.58% at 420 ± 20 nm. In contrast, by replacing electron-neutral benzene instead of electron-withdrawing benzothiadiazole, P2 shows obvious hypochromatic shift in the absorption and large optical band gap of about 2.9 eV, as well as poor photocatalytic property. [ABSTRACT FROM AUTHOR]