title: Achieving nano-gold stability through rational design.
abstract: When Au is subdivided to the nanoscale its reactivity changes from an inert nature to one of incredible reactivity which is not replicated by other catalysts. When dispersed onto metal oxides such as TiO2, nano-Au has shown high reactivities for a multitude of reduction and oxidation reactions of industrial importance with potential and current uses such as, CO oxidation, NOxreduction, purification of hydrogen for fuel cells, water gas shift reactions, abatement of volatile organic compounds (VOC's) as well as pollution and emission control systems such as autocatalysts. However, many industrially important reactions and applications operate under harsh conditions where the catalyst is exposed to high temperatures and further needs to operate for extended periods of time. These conditions cause Au nanoparticle sintering whereby small, highly active clusters form large clusters which are catalytically inactive. For this reason, research into stabilizing Au nanoparticles has abounded with a goal of producing durable, thermally stable catalysts for industrial applications. Here we show a durable, thermally stable Au-TiO2catalyst which has been developed by rational design. The catalyst exhibits a 3-dimensional, radially aligned nanorod structure, already locked into the thermodynamically stable polymorph,viaa scalable and facile synthesis, with Au nanoparticles isolated on the support structure. As the Au nanoparticles are highly stable the new catalyst is able to maintain light-off for CO oxidation below 115 °C even after multiple cycles at 800 °C. This ability of the catalyst to resist multiple thermal cycles to high temperature while remaining active at low temperatures shows promise for various industrial applications. The thermal stability of the catalyst is investigated and characterized through morphological and structural studies.
authors.affiliation: Molecular Sciences Institute , School of Chemistry , University of the Witwatersrand , Private Bag PO Wits , Braamfontein , 2050 , South Africa . Email: paul.franklyn@wits.ac.za; Brazilian Synchrotron Light Laboratory (LNLS)/Brazilian Center for Research in Energy and Materials (CNPEM) , C. P. 6192 , 13083-970 , Campinas , SP , Brazil . Email: dean.barrett@lnls.br.
authors.forename: Dean H
authors.initials: DH
authors.lastname: Barrett
authors.affiliation: Molecular Sciences Institute , School of Chemistry , University of the Witwatersrand , Private Bag PO Wits , Braamfontein , 2050 , South Africa . Email: paul.franklyn@wits.ac.za; Dept. of Civil & Chemical Engineering , University of South Africa , Johannesburg , Florida 1710 , South Africa.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Scurrell
authors.affiliation: Brazilian Synchrotron Light Laboratory (LNLS)/Brazilian Center for Research in Energy and Materials (CNPEM) , C. P. 6192 , 13083-970 , Campinas , SP , Brazil . Email: dean.barrett@lnls.br.
authors.forename: Cristiane B
authors.initials: CB
authors.lastname: Rodella
authors.affiliation: Canadian Light Source , 44 Innovation Boulevard , Saskatoon , SK S7N 2V3 , Canada.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Diaz
authors.affiliation: Molecular Sciences Institute , School of Chemistry , University of the Witwatersrand , Private Bag PO Wits , Braamfontein , 2050 , South Africa . Email: paul.franklyn@wits.ac.za; DST-NRF Centre of Excellence in Strong Materials , School of Chemistry , University of the Witwatersrand , Private Bag PO Wits , Braamfontein , 2050 , South Africa.
authors.forename: David G
authors.initials: DG
authors.lastname: Billing
authors.affiliation: Molecular Sciences Institute , School of Chemistry , University of the Witwatersrand , Private Bag PO Wits , Braamfontein , 2050 , South Africa . Email: paul.franklyn@wits.ac.za.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Franklyn