Abstract:
The present work demonstrates the facile
synthesis and applications of carbon dots (CD)-embedded
Bi2MoO6 nanoplates photocatalyst in the oxidative coupling
of amines and oxidation of toluene and ethylbenzene. The
synthetic protocol is applied to afford good yields of
benzimidazole/benzothiazole via the cascade reaction between benzylamine and o-aminothiophenol/o-phenylenediamine. These photocatalytic reactions are performed under
very mild conditions using the household light-emitting diode
bulb as a light source and O2 (1 atm). The CD-embedded, 2.4
wt % CD/Bi2MoO6 exhibits the best photocatalytic activity.
Impressive visible-light absorbance coefficient, quantum
confinement, photoluminescence up-conversion, and stable photoelectrochemical properties of CD are contemplating the
excellent photocatalytic activity of CD/Bi2MoO6 than the pristine Bi2MoO6. Generation and influence of various reactive
species in these catalytic reactions are investigated by radical scavenging, fluorescence spectroscopy, and cyclic voltammetric
(CV) analysis. Both qualitative and quantitative estimation of the in situ generated H2O2 in the photocatalytic oxidative
coupling of amines was ascertained using CV and redox titration, respectively. Further, the influence of substitution in the
benzylamine and involvement of the carbocations are confirmed using Hammett plot. The developed catalysts are also used as
photoanode for O2 evolution from water oxidation in a photoelectrochemical (PEC) cell. Several PEC techniques evaluate the
PEC activity of the photoanodes. The reactivity order for various substituted benzylamine and the involvement of reactive
oxygen species (O2·
−) in the oxidation reaction was obtained and confirmed from the band edge potentials of the best
photocatalyst using Mott−Schottky analysis. Efficient catalytic recyclability and photostability are additional important features
of the present investigation. This study provides a feasible alternative to the development of non-noble metal (CD)-based
nanocomposite photocatalysts that can manifest important photocatalytic and photoelectrocatalytic applications in chemical
synthesis and solar fuel production.
