TiO2-supported copper nanoparticles prepared via ion exchange for photocatalytic hydrogen production

This thesis presents the findings from a study on TiO2-supported copper nanoparticles (Cu/TiO2) synthesised using an ion exchange (IE) – heat treatment process. The IE Cu/TiO2 particles were assessed as photocatalysts for hydrogen generation from an aqueous solution (10 vol. %) of methanol. Photocatalytic activity displayed by the IE Cu/TiO2 was compared with Cu/TiO2 prepared by wet impregnation (WI) and reasons for the differences in performance were investigated. The particle synthesis approach comprised three key stages: (1) hydrothermal synthesis to produce sodium titanate; (2) ion-exchange of sodium titanate to produce copper titanate; (3) calcining/reducing the copper titanate to give Cu/TiO2. Calcining invoked the transformation from high surface area titanate to TiO2 nano-crystals accompanied by the relocation of copper ions from between the titanate layers to the TiO2 particles surface in the form of copper oxide deposits. Dehydration of intra-layered and interlayered OH group during the heat treatment may induce the TiO6 group arrangement and the formation of anatase crystals as revealed by XRD results. The presence of anatase at an earlier heat treatment temperature compared with CuO indicates a faster formation, which was attributed to the comparatively faster rate of Ti-O-Ti bond formation during the calcination compared with Ti-O-Cu bond formation. The formation of Cu-O covalent bonds after calcination in air was confirmed by Raman Spectroscopy. The IE method produced Cu/TiO2 particles with a high (~19 wt. %) Cu loading which, from H2 temperature programmed reduction (TPR) studies, was observed to comprise a mixture of large and fine copper/copper oxide deposits well dispersed across the TiO2 surface. H2-TPR results also indicated the fine copper deposits interacted strongly with the TiO2 support. The rate of photocatalytic hydrogen generation by the IE Cu/TiO2 was ~44 % greater than that displayed by WI Cu/TiO2 (with a similar copper loading). The better performance exhibited by the IE Cu/TiO2 was attributed to the greater portion of highly dispersed, strongly interacting Cu deposits induced by the IE synthesis method. In addition, the photocatalytic activity displayed by the IE Cu/TiO2 was maintained over three sequential 5 hr. reaction cycles highlighting the stability of this material for hydrogen generation.

Grantor dc:publisher

UNSW, Sydney

Year dc:date

2014

Author dc:creator

• Tian, Hao

• Titanium dioxide
• Photocatalyst
• Hydrogen production

Statement dc:rights

• open access
• CC BY-NC-ND 3.0
• free_to_read

Licence

• https://purl.org/coar/access_right/c_abf2
• https://creativecommons.org/licenses/by-nc-nd/3.0/au/

Language dc:language

EN

Identifier

https://doi.org/10.26190/unsworks/16945

OAI identifier oai:identifier

oai:unsworks.library.unsw.edu.au:1959.4/53718