Significant improvement of photocatalytic hydrogen evolution of diketopyrrolopyrrole-based donor-acceptor conjugated polymers through side-chain engineering
Donor-acceptor (D-A) type conjugated organic polymers exhibited great potential for photocatalytic hydrogen evolution due to their diverse synthetic approaches, tunable energy band and electronic structure. But the poor dispersion of most conjugated organic polymers limited their photocatalytic performance. Herein, we designed and developed a series of D-A type conjugated organic polymers with benzene as the donor and diketopyrrolopyrrole (DPP) with different side chains on N sites as the acceptor. We changed the length of the side chain and further introduced oxygen atoms on side chains. As a result, the hydrogen evolution rate (HER) of PDPP3B-O4 with short butoxy chain as side chain was 5.53 mmol h−1 g−1 with 1 wt% Pt loading (λ > 400 nm), increased by 110 times than PDPP3D-C8 with long octyl chain. All polymers showed outstanding photocatalytic stability. Notably, an apparent quantum yield (AQY) of 5.7 % at 450 nm was achieved by the PDPP3B-O4, and even a still high AQY of 1.13% at 600 nm was obtained due to its excellent light capture capability. PDPP3B-O4 showed a superior photocatalytic performance because of wider absorption spectrum and better wettability via side chain engineering.