Interplay of Corrosion and Photocatalysis During Nonaqueous Benzylamine Oxidation on Cadmium Sulfide

Abstract

The photo(electro)chemical properties of bulk, nanowire, and chemical bath deposits of cadmium sulfide (CdS) for benzylamine oxidation to N-benzylidenebenzylamine (N-BB) in acetonitrile have been evaluated as a model for the activity and stability of CdS toward selective organic oxidations. CdS photocatalysts selectively deliver N-BB at rates ranging from 5 to 26 mM h −1 . Although CdS is a capable photocatalyst, SEM imaging and XPS analysis reveal significant morphological and compositional changes to the particles upon photolysis in benzylamine. These surface changes and surface sulfide oxidation are accompanied by Cd 2+ leaching and hydrogen sulfide evolution, highlighting both redox and acid−base pathways of nonaqueous CdS corrosion. All facets of corrosion have been linked directly with amine reactivity, as the CdS particles are unaffected by substrate-free photolysis. A series of experiments using N,N-dimethylbenzylamine, 4-N,N-trimethylaniline, and ferrocene show that nonaqueous CdS corrosion is facilitated by acidic reaction intermediates opposed to photogenerated holes. Additionally, water and oxygen are essential components to corrosion, as photoelectrochemistry under dry/air-free conditions displays higher and stable photocurrent density as well as material stability. Finally, CdS nanowires display improved corrosion resistance, suggesting that control of particle morphology and/or electronic structure is essential for developing novel chalcogenide photocatalysts.

Visible Light‐driven Dehydrogenation of Benzylamine under Liberation of H2

“…The corrosion of CdS is a frequently discussed phenomenon and a main challenge in the use of such photocatalysts . Recently, DiMeglio and co‐workers reported on the benzylamine mediated oxidation of sulfide during the non‐aqueous dehydrogenation of benzylamine with O 2 as a sacrificial agent . The standard reduction potential of benzylamine thermodynamically allows for the oxidation of CdS via the formation of the amine‐radical cation.…”

Enhanced photocarriers separation of novel CdS/pt/Mo2C heterostructure for visible-light-driven hydrogen evolution

“…Compared with other samples, CdS/Pt/Mo 2 C-0.5 possesses apparent quantum yield of 9.39% (AQY ¼ 9.39%) under visible-light irradiation. 25,[28][29][30][31][32][33] Interestingly, upon further increasing the percent of Pt nanoparticles, the rate for photocatalytic hydrogen generation decreases, which is probably due to the extra percent of Pt nanoparticles in the CdS/Pt/Mo 2 C system. The excessive Pt may act as the center of recombination, which has been proven by previous research.…”

Organic semiconductor photocatalyst can bifunctionalize arenes and heteroarenes

“…Direct C-H trifluoromethylations, difluoromethylations, perfluoroarylations of arenes, and medicinally relevant molecules by means of oxidative or reductive radical reactions. *NMR yield by 19 F NMR. †The bifunctionalized product was obtained in 14% isolated yield.…”