A summary of using the pore chemistry or surface chemistry of MOFs to construct heterojunction nanocatalysts for photocatalytic hydrogen production.

Fabricating heterojunction photocatalysts for H2 production is promising for the development of clean energy. For boosting the photocatalytic activity, modulating the heterojunction interface can facilitate the electron–hole separation and solar energy utilization, but it is highly challenging in synthesis. In this work, by facilely exfoliating the bulk C3N5, ultrathin C3N5 nanosheets (N-CN) with large surface area, improved light absorption, and efficient charge transport were synthesized and further applied to the construction of NH2-UiO-66/N-CN heterojunctions. The optimized NH2-UiO-66/N-CN-2 exhibits high hydrogen evolution rate and cycling stability with Pt as the cocatalyst. Combined with the experimental results, the density functional theory calculation reveals that the high photocatalytic performance is attributed to the promoted photogenerated carrier transfer by the formation of well-contacted and stable Z-scheme heterojunction interface. This contribution renders an insight into the modulation of the heterojunction interface for enhancing the activity of MOF-based photocatalysts.

No abstract

Photocatalytic water splitting taking the advantage of using solar energy directly is one of the most effective strategies for hydrogen evolution. The development of facile methods for synthesizing highly efficient and stable photocatalysts for hydrogen production still remains a great challenge. Herein, a metal–organic framework (MOF)-templated strategy was designed for the synthesis of solid solutions of (Zn0.95Cu0.05)1–x Cd x S that exhibit outstanding photocatalytic hydrogen production reaction activity. More importantly, efficient light capturing ability and photogenerated charges separation were accomplished via fine-tuning the composition of the photocatalysts by adjusting the concentrations of doping metals in the template MOFs. Under visible light (λ > 420 nm), an optimized nanocatalyst, (Zn0.95Cu0.05)0.6Cd0.4S, exhibited a higher durability and satisfied photocatalytic hydrogen evolution rate of 4150.1 μmol g–1 h–1 of water splitting.

Trisubstituted piperazinones, piperazines, tetrahydropyrazines, and dihydropyrazinones were prepared in a one‐step procedure from easily accessible polymer‐supported acyclic precursors containing either a masked aldehyde or ketone group. Acid‐mediated unmasking of the aldehyde triggered cyclic iminium formation followed by reduction with triethylsilane present in the cleavage cocktail. The effect of the substituent at the iminium‐forming nitrogen was evaluated: whereas complete conversion to the target compounds was observed with N‐alkyl, aryl, and phenylsulfonamido derivatives, the N‐acyl compound suffered from a partial reduction of the aldehyde to an alcohol. Similarly, ketones readily provided cyclic iminiums with N‐alkyl compounds, whereas their cyclization with N‐acyl precursors proceeded unwillingly. Interestingly, cleavage of the resin‐bound acyclic precursor at 60 °C in the presence of triethylsilane resulted in the decomposition of the amide bond and formation of a lactone. An analogous synthetic route was also successfully used for the preparation of piperazines and tested as an alternative route for the synthesis of diazepanones.