Fluorenone-based covalent organic frameworks with efficient exciton dissociation and well-defined active center for remarkable photocatalytic hydrogen evolution

Post-synthetic modulation of UiO-66-NH2 with a cobaloxime catalyst for efficient hydrogen production

“…31 The positively shifted value for Co-UiO suggests better charge accumulation on the material, which is beneficial for photoinduced electron transport. 32 Typically, the conduction band minimum (CBM) of an n-type semiconductor lies 0.1 V lower than the flat-band potential. 25 Hence, the current values suggest that the CBM for UiO-66-NH 2 and Co-UiO is conducive to H 2 production as it is cathodically positioned compared to the H + /H 2 potential.…”

Recent advances on covalent organic frameworks (COFs) as photocatalysts: different strategies for enhancing hydrogen generation

“…Hence, strong electron-absorbing groups (like halogen atoms, heteroatomic atoms) and electron-donating groups (like methyl, methoxy) are often adopted to modify COF structures to boost photocatalytic HER. [69][70][71][72][73][74][75][76][77][78][79][80] Halogen atoms as typical electron-absorbing groups exhibit good electronegativity, which can regulate the localized electron cloud density and delocalization of conjugated building blocks and promote the separation transfer of electrons to enhance HER ability. Chen et al selected a benzothiadiazole (BT) acceptor as a qualifiable building block to fabricate Py-XTP-BT-COFs (X = H, F, Cl) via chlorination and fluorination (Fig.…”

“…Hence, strong electron-absorbing groups (like halogen atoms, heteroatomic atoms) and electron-donating groups (like methyl, methoxy) are often adopted to modify COF structures to boost photocatalytic HER. 69–80…”

Rational Regulation of the Exciton Effect of Acrylonitrile-Linked Covalent Organic Framework toward Boosting Visible-Light-Driven Hydrogen Evolution

“…Combined with the low exciton binding energy of TP-PN COF, TP-BPyN COF, and TP-BPyN PCOF from temperature-dependent PL (Figure 3e−g), it can be inferred that the D−A effect strengthened by shortening the linker length, introducing the nitrogen atoms, and post-protonation, thus decrease exciton binding energy to promote exciton dissociation and improve the charge separation. 27,55 On this basis, the band structures and band gap of COFs were calculated. The results (Figure S29) indicate that the band gap values of TP-BPN COF, TP-PN COF, TP-BPyN COF, and TP-BPyN PCOF are 2.10, 2.04, 2.18, and 2.15 eV, respectively, only minor differences between the bandgaps measured by UV−vis DRS (Figure 3b,c).…”