Liang Chen

Abstract Metal‐free polymer photocatalysts have shown great promise for photocatalytic H 2 O 2 production via two‐electron reduction of molecular O 2 . The other half‐reaction, which is the two‐electron oxidation of water, still remains elusive toward H 2 O 2 production. However, enabling this water oxidation pathway is critically important to improve the yield and maximize atom utilization efficiency. It is shown that introducing acetylene (CC) or diacetylene (CCCC) moieties into covalent triazine frameworks (CTFs) can remarkably promote photocatalytic H 2 O 2 production. This enhancement is inherent to the incorporated carbon–carbon triple bonds which are essential in modulating the electronic structures of CTFs and suppressing charge recombinations. Furthermore, the acetylene and diacetylene moieties can significantly reduce the energy associated with OH* formation and thus enable a new two‐electron oxidation pathway toward H 2 O 2 production. The study unveils an important reaction pathway toward photocatalytic H 2 O 2 production, reflecting that precise control over the chemical structures of polymer photocatalysts is vital to achieve efficient solar‐to‐chemical energy conversion.

Creating ordered two-dimensional (2D) metal-organic framework (MOF) nanosheets has attracted extensive interest. However, it still remains a great challenge to synthesize ultrathin 2D MOF nanosheets with controlled thickness in high yields. In this work, we demonstrate a novel intercalation and chemical exfoliation approach to obtain MOF nanosheets from intrinsically layered MOF crystals. This approach involves two steps: first, layered porphyrinic MOF crystals are intercalated with 4,4'-dipyridyl disulfide through coordination bonding with the metal nodes; subsequently, selective cleavage of the disulfide bond induces exfoliation of the intercalated MOF crystals, leading to individual freestanding MOF nanosheets. This chemical exfoliation process can proceed efficiently at room temperature to produce ultrathin (∼1 nm) 2D MOF nanosheets in ∼57% overall yield. The obtained ultrathin nanosheets exhibit efficient and far superior heterogeneous photocatalysis performance compared with the corresponding bulk MOF.