Bottom-up wet-chemical synthesis of a two-dimensional porous carbon material with high supercapacitance using a cascade coupling/cyclization route

Abstract

Wet-chemical bottom-up synthesis methods for two-dimensional (2D) layered materials are less explored than the top-down exfoliation of bulk materials. Here, we set out to synthesize a graphyne-type material by a wet-chemical synthesis method using Sonogashira–Hagihara cross-coupling polycondensation of a multifunctional monomer, 2, bearing alkyne and vinyl bromide functionalities. Spectroscopic and chemical analysis revealed that upon C–C bond formation, an unanticipated Bergman cyclization occurred to give an aromatic 2D porous carbon material (2D-PCM). 2D-PCM is a black material with graphene-like layers and a bulk structure that is similar to irregular graphite. It is porous with a hierarchical pore structure and an apparent Brunauer–Emmett–Teller surface area of 575 m² g⁻¹. The material has excellent electrochemical performance as an electrode in supercapacitors with a specific capacitance of 378 F g⁻¹ at the current density of 0.1 A g⁻¹, which surpasses state-of-the-art carbon materials, suggesting that wet-chemical methods might give functional benefits over top-down processing routes.