Efficient Photoinduced Electron Transfer from Pyrene‐o‐Carborane Heterojunction to Selenoviologen for Enhanced Photocatalytic Hydrogen Evolution and Reduction of Alkynes

A series of pyrene or pyrene‐o‐carborane‐appendant selenoviologens (Py‐SeV(2+), Py‐Cb‐SeV(2+)) for enhanced photocatalytic hydrogen evolution reaction (HER) and reduction of alkynes is reported. The efficient photoinduced electron transfer (PET) from electron‐rich pyrene‐o‐carborane heterojunction (Py‐Cb) with intramolecular charge transfer (ICT) characteristic to electron‐deficient selenoviologen (SeV(2+)) (k (ET) = 1.2 × 10(10) s(−1)) endows the accelerating the generation of selenoviologen radical cation (SeV(+•)) compared with Py‐SeV(2+) and other derivatives. The electrochromic/electrofluorochromic devices’ (ECD and EFCD) measurements and supramolecular assembly/disassembly processes of SeV(2+) and cucurbit[8]uril (CB[8]) results show that the PET process can be finely tuned by electrochemical and host–guest chemistry methods. By combination with Pt‐NPs catalyst, the Py‐Cb‐SeV(2+)‐based system shows high‐efficiency visible‐light‐driven HER and highly selective phenylacetylene reduction due to the efficient PET process.