Construction of organic semiconducting materials with in-plane π-conjugated structures and robustness through carbon-carbon bond linkages, alternatively as organic graphene analogs, is extremely desired for powerfully optoelectrical conversion. However, the poor reversibility forsp²carbon bond forming reactions makes them unavailable for building high crystalline well-defined organic structures through a self-healing process, such as covalent organic frameworks (COFs). Here we report a scalable solution-processing approach to synthesize a family of two-dimensional (2D) COFs withtrans-disubstituted C = C linkages via condensation reaction at arylmethyl carbon atoms on the basis of 3,5-dicyano-2,4,6-trimethylpyridine and linear/trigonal aldehyde (i.e., 4,4″-diformyl-p-terphenyl, 4,4′-diformyl-1,1′-biphenyl, or 1,3,5-tris(4-formylphenyl)benzene) monomers. Suchsp²carbon-jointed-pyridinyl frameworks, featuring crystalline honeycomb-like structures with high surface areas, enable driving two half-reactions of water splitting separately under visible light irradiation, comparable to graphitic carbon nitride (g-C₃N₄) derivatives.

The synthesis of crystalline two-dimensional (2D) covalent organic frameworks (COFs) with fully unsaturated carbon–carbon backbones via a solution approach remains a great challenge. In this work, we report the first example of an olefin-linked 2D conjugated COF using a Knoevenagel polycondensation reaction of 1,4-phenylene diacetonitrile and three armed aromatic aldehyde. The resulting 2D poly(phenelyenevinylene) framework (2DPPV) possesses a sheet morphology, and a crystalline layered structure featuring a fully sp²-bonded carbon skeleton with pendant cyanide groups. Its unique alternating structure with a serrated configuration has been essentially evaluated using HR-TEM TEM analysis, nitrogen physisorption measurements, PXRD studies and theoretical simulations. Upon thermal and activation treatments, the as-prepared 2DPPV can be facilely converted into porous carbon nanosheets with large specific surface areas of up to 880 m² g⁻¹ which exhibit an excellent electrochemical performance as supercapacitor electrodes and electrocatalysts for the oxygen reduction reaction. This represents an economic non-template approach to 2D porous carbon materials for energy-related applications.