Ordered mesoporous Au/TiO2 nanospheres for solvent-free visible-light-driven plasmonic oxidative coupling reactions of amines

Jingling Yang, Chung Yuan Mou

Research output: Contribution to journalArticlepeer-review

70 Citations (Scopus)

Abstract

Imines are important intermediates for the synthesis of fine chemicals and pharmaceuticals. Design of a “green” oxidation catalyst to promote the direct oxidation of amines to imines by dioxygen have attracted great attention. Herein, we designed a catalyst of ordered mesoporous Au/M-TiO2 nanoparticles using a template-based approach. The as-prepared Au/M-TiO2 nanoarrays of anatase crystalline structure, with high specific surface area (222 m2/g), small pore size (∼2.1 nm) and ordered arrangements, gave dense array of ultrasmall pore-confined gold nanoparticles. The mesoporous Au/M-TiO2 exhibits particularly high visible light activity for photocatalytic selective aerobic oxidation of benzylamine to N-benzylidene benzylamine in a green approach by utilizing dioxygen as an oxidant in solvent-free conditions. The yield of N-benzylidene benzylamine can reach 1.73 mmol (TOF = 178.6 h−1, based on Au) in Au/M-TiO2 system, which is 1.5 and 1.6 times higher than that of the Au/P25 and Au/Acros anatase photocatalysts, respectively. Furthermore, we can also achieve high yield of N-benzylidene benzylamine (1.30 mmol, TOF = 134.2 h−1, based on Au) in air atmosphere. The confinement effect of the mesopores in Au/M-TiO2 facilitate the formation of [rad]O2 radicals and make the bi-molecular reaction highly preferred for promoting the high selectivity and conversion in plasmonic photocatalysis. Meanwhile, the Au/M-TiO2 with mesoporous structure can facilitate the efficient contact between the solvent and the nanomaterial, while possessing sufficient interfacial area for active oxidation reactions. This work paves a promising way to develop visible light-responsive TiO2-based photocatalysts with high specific surface area for highly efficient green oxidative organic synthesis.

Original languageEnglish
Pages (from-to)283-291
Number of pages9
JournalApplied Catalysis B: Environmental
Volume231
DOIs
Publication statusPublished - Sep 5 2018
Externally publishedYes

Keywords

  • Au/TiO
  • Confinement effect
  • Plasmonic photocatalysis
  • Solvent-free

ASJC Scopus subject areas

  • Catalysis
  • Environmental Science(all)
  • Process Chemistry and Technology

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