Rational Design of Electron Transfer Kineties of CdS/Zn(impim) Dots-on-Rods for Efficient Visible-Light Reduced C-X Bond

Halogenated organic compounds are a kind of common environmentalpollutants. Photocatalytic dehalogenation of C-halogen (C-X)bonds to C-H bonds can not only control environmental pollutionbut also realize important organic conversion reactions. However,the electron transfer kinetics of photocatalytic reduction of theC-X bond for semiconductor/MOF composites has remained unexplored.Herein, we successfully synthesized CdS/Zn(impim) (MOF) dots-on-rodscomposite photocatalyst under mild conditions. Zn(impim) MOF consistsof Zn(& mu;-N)(4) clusters and imidazole derivative ligands.Zn(impim), as a carrier, is beneficial to the dispersion of CdS nanoparticlesand avoiding the agglomeration of CdS nanoparticles. The photocatalyticperformance of CdS/Zn(impim) composites for the reduction of the C-Xbond is much higher than that of pure CdS or Zn(impim). This highactivity is due to the high electron separation efficiency of CdSassisted by Zn(impim). Under visible light irradiation, Zn(impim)is not excited due to its wide band gap of 3.26 eV. Through metal-to-ligandcharge transfer of Zn(& mu;-N)(4) clusters, Zn(impim) acceptsexcited electrons from CdS because the Fermi energy level of CdS ismore negative by Kelvin probe force microscopy. Moreover, fluorescencespectrum and femtosecond transient absorption spectroscopy revealthe related electron transfer kinetics in detail. In addition, theinherent porous structure of MOFs is beneficial to the adsorptionof halogenated hydrocarbons, providing a suitable environment forthe dehalogenation reaction, thus improving the activity. This workcan further understand the electron transfer mechanism in semiconductor/MOFcomposites for photocatalytic halide dehalogenation.

Automated summary

CdS/Zn(impim) composite photocatalyst was synthesized and achieved photocatalytic dehalogenation through electron transfer mechanism, improving the photocatalytic performance.