Post-cyclization of a bisimine-linked covalent organic framework to enhance the performance of visible-light photocatalytic hydrogen evolution

Covalent organic frameworks (COFs) are promising candidates for the photocatalytic hydrogen evolution. Here, we reported the synthesis of a bisimine-linked COF and its partial post-cyclization to an imidazolium-linked COF. Both the chemical stability and π-electron delocalization are significantly improved by the post-cyclization, leading to a triply increased hydrogen evolution rate.