Construction of Efficient D–A-Type Photocatalysts by B–N Bond Substitution for Water Splitting

Donor–acceptor (D–A)-type conjugated polymers are emerging as a promising platform for solar to chemical energy conversion, such as water splitting to H2 production. Disclosed herein is a new strategy that makes it possible to transform conventional conjugated polymers into D–A-type conjugated polymers by B–N bond substitution while retaining the original backbone. Using this method, we synthesize two conjugated polymers PCCP and PBNP, where PBNP containing the B–N bonds has a strong built-in electric field and a lower exciton binding energy (Eb) for solar-driven photocatalytic hydrogen evolution. PBNP without any co-catalyst addition exhibits a high hydrogen evolution rate (HER) of more than 9445 μmol g–1 h–1 for water splitting under AM 1.5G sunlight illumination (100 mW cm–2), a 28 times improvement relative to PCCP (333 μmol g–1 h–1). In addition, another contrasting BN-substituted D–A polymer PBNN also exhibits an excellent HER of 5740 μmol g–1 h–1. Theoretical and experimental studies confirm that the substitution of B–N bonds can completely change the electronic properties of the original polymer, allowing rapid charge separation and transfer. This work opens up new prospects for the preparation of efficient D–A conjugated polymer photocatalysts.