Low efficiency of photogenerated electron-hole separation has been a challenge for organic conjugated polymer photocatalysts. Our preceding studies have revealed that polymers containing B←N coordination bond can form a localized built-in electric field that effectively promotes photogenerated charge separation. However, B←N coordination units are still scarce and require more examples to find regularities in their structural design. The systematic development and testing of B←N coordination units is necessary for the efficient development of subsequent polymers containing B←N coordination bond. In this work, three conjugated polymers containing B←N coordination bonds, PBN-Ni, PBP-Ni, and PBS-Ni, were synthesized by changing the substituents of the boron atoms and introducing narrow-band thiophene units to form conjugate and energy band gradients. The energy band modulation and localized built-in electric field construction were both achieved as planned, while the bandgap and photogenerated charge transport capabilities caused performance discrepancies. The experimental results showed that PBN-Ni had a better photocatalytic hydrogen evolution (HER) performance, reaching 104.6 µmol h-1 (λ > 420 nm). The optimal optical absorption edge of PBS-Ni was up to 643 nm, but the HER was lower, at 33.2 µmol h-1 (λ > 420 nm, 1 % Pt). PBP-Ni optimized some of the optical absorption efficiencies (511 nm) while ensuring the HER activity (96.6 µmol h-1, λ > 420 nm). This work tentatively explores the characterization of the B←N coordination bond-containing base units serving as photocatalysts and provides the basic model experience and data reference for the subsequent expansion of B←N coordination bond-containing units and the development of B←N coordination bond-containing copolymer systems.

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