Electron-deficient covalent organic frameworks anchored on melamine sponges for visible-light-driven H2O2 evolution

A series of covalent organic frameworks (COFs) with beta-ketoenamine linkages named TpTt-COF, TAPT-COF, and TpPa-1 were constructed for photocatalytic H2O2 generation in pure water and ambient air under visible light. Among them, TpTt-COF performed striking H2O2 yield of 2647 mu mol L-1, which is 3.5, 17.5, and 176.5-fold those of TAPT-COF, TpPa-1, and bulk g-(CN4)-N-3, respectively, attributing to the electron-deficient trait, short charge diffusion distance, and the narrowest bandgap of TpTt-COF. Additionally, to achieve the facile recovery, TpTt-COF was firmly and evenly anchored on melamine sponges (MS) because plenty of amino groups on the surface of MS could be involved in the beta-ketoenamine formation and guide the synthesis of TpTt-COF on MS. The corresponding H2O2 evolution over this photocatalyst monolith is also respectable and can be well repeated at least four times. This work is quite instructive for photocatalyst construction based on covalent organic frameworks and facile photocatalytic applications.