Journal Article

Two-dimensional (2D) conjugated frameworks are promising candidates for efficient solar-fuel conversion. However, they still face challenges including poor light capture, rapid exciton recombination and insufficient active sites. The introduction of donor-acceptor (D-A) segments and metal units into the highly conjugated 2D frameworks is an effective strategy to address these issues. Here, a NiII-acetylide framework (TBTT-Ni-GY) is constructed by incorporating NiII-complexes into the highly conjugated 2,5,8-triethynylbenzo[1,2-b:3,4-b':5,6-b"]trithiophene (TBTT)-based graphdiyne framework through NiII-bis(acetylide) (- C---C-Ni-C---C-) linkages. TBTT-Ni-GY achieves an impressive selectivity of ca. 100 % for CO generation (100.55 mu mol g-1 h-1) without the need for co-catalyst or photosensitizer in the CO2 photoreduction system. Spectroscopic techniques and theoretical calculations reveal that TBTT-Ni-GY exhibits broadened absorption and distinctive fully conjugated D-it-A characteristics, in which the BTT unit serves as the electron donor and the NiII-complex block acts as both the electron acceptor and photocatalytic site to facilitate the directional electron transport, with the sp-carbon (-C---C-) serving as the it-linker, thereby facilitating photoinduced exciton dissociation and promoting efficient photocatalysis. Notably, the NiII-bis(acetylide) moiety enhances the adsorption and activation of CO2 and suppresses H2 release, achieving high CO selectivity. This work provides a compelling paradigm for engineering high-performance and low-cost metal-containing catalysts within the family of metal-acetylide frameworks.