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

Abstract

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 H2 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.