Precisely Tuning Band Gaps of Hexabenzocoronene-Based MOFs Toward Enhanced Photocatalysis

Abstract

Precise adjusting the band gaps in metal–organic frameworks (MOFs) is crucial for improving their visible-light absorption capacity during photocatalysis, presenting both a formidable challenge and a charming opportunity. This present study employed a symmetry-reduction strategy to pre-design six novel 4-connected ligands with systematic substituents (−NO₂, -H, -^tBu, -OCH₃, -OH and -NH₂) and synthesized the corresponding pillared-layer Zr-MOFs (NKM-668) retaining the hexaphenylbenzene fragment. Subsequently, the NKM-668 MOFs were transformed into large-π-conjugated hexabenzocoronene-based MOFs (pNKM-668) via the Scholl reaction. These twelve MOFs exhibited broad and tunable band gaps over 1.41 eV (ranging from 3.25 eV to 1.84 eV), and the photocatalytic CO₂ conversion rate raised by 33.2-fold. This study not only enriches the type of hexaphenylbenzene-based MOFs, but also paves the way for nanographene-containing MOFs in the further application of photocatalysis.