Self-assembly of Au nanocrystal/titanate nanobelt heterojunctions and enhancement of the photocatalytic activity

In the present work, we introduce a facile and widely used route to fabricate Au nanocrystal/titanate nanobelt heterojunctions with high yield, well dispersion and tight interaction, which are self-assembled via the linker molecule of thioglycolic acid. Their photocatalytic activity for the degradation of methyl orange solution will be enhanced with the decorating with Au nanocrystals, especially in visible light region. The degradation ratio of the heterojunctions with 5 wt% Au nanocrystals is the best one, and it will increase to 99.8% and 81% from 33% and 2% for pure titanate nanobelts after 120 min’ irradiation under the UV and visible light irradiation, respectively, especially, the degradation ratio increases to 99.5% after 300 min’ visible light irradiation comparing with that of 5% for pure titanate nanobelts. The results are quite better than that of others’ similar reports, as the heterojunctions will suppress the recombination of electron–hole pairs in titanate nanobelts, where the Au particles act as electron traps aiding electron–hole separation, moreover, the efficiently coupled surface plasmon resonance (SPR) excitation by Au nanocrystals in visible light region induces a synergistic effect of the tight contact between Au nanocrystals and titanate nanobelts.

Photo-degradation curves of titanate nanobelts and heterojunctions: (a) under UV-light irradiation; (b) under visible light irradiation.Figure optionsDownload high-quality image (219 K)Download as PowerPoint slideHighlights
► Au nanocrystal/titanate nanobelt heterojunctions are self-assembled via the linker molecule of thioglycolic acid.
► Degradation ratio of the 5 wt% Au heterojunctions is of 99.8% and 81% after 120 min’ irradiation under the UV and visible light irradiation, respectively.
► Heterojunctions will suppress the recombination of electron–hole pairs in titanate nanobelts.
► SPR excitation favors for the migration of photo-excited electrons and acceleration of production of superoxide and hydroxyl radicals.