Constructing photocatalyst systems to functionalize the inert C−H bonds has attracted extensive research interest. However, purposeful modulation of interfacial charge transfer in heterostructures remains a challenge, as it usually suffers from sluggish kinetics. Reported herein is an easy strategy to construct the heteroatom‐induced interface for developing the titanium‐organic frameworks (MOF‐902) @ thiophene‐based covalent triazine frameworks (CTF‐Th) nanosheets S‐scheme heterojunctions with controllable oxygen vacancies (OVs). Specifically, Ti atoms were first anchored onto the heteroatom site of CTF‐Th nanosheets, and then grown into MOF‐902 via an interfacial Ti−S linkage, generating OVs. Using in situ X‐ray photoelectron spectroscopy (XPS), extended X‐ray absorption fine structure (EXAFS) spectroscopy and density functional theory (DFT) calculations, the enhanced interfacial charge separation and transfer induced by moderate OVs in the pre‐designed S‐scheme nanosheets was validated. The heterostructures exhibited an improved efficiency in photocatalytic C3‐acylation of indoles under mild conditions with a yield 8.2 times larger than pristine CTF‐Th or MOF‐902 and enabled an extended scope of substrates (15 examples). This performance is superior to state‐of‐the‐art photocatalyst and can be retained, without significant loss, after 12 consecutive cycles.

The sluggish charge-transfer kinetics of Fe(II) regeneration, unsatisfactory utilization of H 2 O 2 , and low reaction efficiency remain largely unresolved in Fe 3 O 4 -based heterogeneous photo-Fenton systems. Herein, an in situ covalent attaching strategy was employed to fabricate Fe 3 O 4 @covalent organic framework (COF) core−shell heterostructures. By virtue of this, enhanced photoresponsive behavior was obtained to tailor the regeneration kinetics for Fe(II) and ideal catalytic sites for H 2 O 2 were provided. Molecular engineering was further employed to manipulate the linkages (β-ketoenamine or imine) of the COFs. Bearing a β-ketoenamine linkage, the Fe 3 O 4 @ TpTta COF exhibited remarkably fast kinetics (0.111 min −1 ) as well as exceptional pH tolerance in photo-Fenton degradation of methylene blue, which stands out among the state-of-the-art photocatalysts. Combined with theoretical calculations, the electron-transfer route and interfacial interactions between the oxidant and catalysts with different linkages were fully revealed, giving insight into the synergistic relationship between photocatalysis and Fenton reactions.

Constructing photocatalyst systems to functionalize the inert CÀ H bonds has attracted extensive research interest. However, purposeful modulation of interfacial charge transfer in heterostructures remains a challenge, as it usually suffers from sluggish kinetics. Reported herein is an easy strategy to construct the heteroatom-induced interface for developing the titanium-organic frameworks (MOF-902) @ thiophenebased covalent triazine frameworks (CTF-Th) nanosheets S-scheme heterojunctions with controllable oxygen vacancies (OVs). Specifically, Ti atoms were first anchored onto the heteroatom site of CTF-Th nanosheets, and then grown into MOF-902 via an interfacial TiÀ S linkage, generating OVs. Using in situ X-ray photoelectron spectroscopy (XPS), extended X-ray absorption fine structure (EXAFS) spectroscopy and density functional theory (DFT) calculations, the enhanced interfacial charge separation and transfer induced by moderate OVs in the pre-designed S-scheme nanosheets was validated. The heterostructures exhibited an improved efficiency in photocatalytic C3-acylation of indoles under mild conditions with a yield 8.2 times larger than pristine CTF-Th or MOF-902 and enabled an extended scope of substrates (15 examples). This performance is superior to state-of-the-art photocatalyst and can be retained, without significant loss, after 12 consecutive cycles.