Sub-15 nm CeO2 nanowires as an efficient non-noble metal catalyst in the room-temperature oxidation of aniline

Author(s):Show less -

da Silva, Anderson G. M. ^[1] ; Batalha, Daniel C. ^[2] ; Rodrigues, Thenner S. ^[3] ; Candido, Eduardo G. ^[1] ; Luz, Sulusmon C. ^[2] ; de Freitas, Isabel C. ^[1] ; Fonseca, Fabio C. ^[3] ; de Oliveira, Daniela C. ^[4] ; Taylor, Jason G. ^[2] ; Cordoba de Torresi, Susana I. ^[1] ; Camargo, Pedro H. C. ^[1] ; Fajardo, Humberto V. ^[2]

Affiliation

^[1] Univ Sao Paulo, Inst Quim, Dept Quim Fundamental, Ave Prof Lineu Prestes 748, BR-05508000 Sao Paulo, SP - Brazil

^[2] Univ Fed Ouro Preto, Dept Quim, BR-35400000 Ouro Preto, MG - Brazil

^[3] IPEN CNEN SP, Inst Pesquisas Energet & Nucl, BR-05508000 Sao Paulo, SP - Brazil

^[4] Ctr Nacl Pesquisa Energia & Mat, Lab Nacl Luz Sincrotron, BR-13083970 Campinas, SP - Brazil

• Document type: Journal article
• Source: CATALYSIS SCIENCE & TECHNOLOGY; v. 8, n. 7, p. 1828-1839, APR 7 2018.
• Web of Science Citations: 9

Abstract

We described herein the facile synthesis of sub-15 nm CeO2 nanowires based on a hydrothermal method without the use of any capping/stabilizing agent, in which an oriented attachment mechanism took place during the CeO2 nanowire formation. The synthesis of sub-15 nm CeO2 nanowires could be achieved on relatively large scales (similar to 2.6 grams of nanowires per batch), in high yields (>94%), and at low cost. To date, there are only a limited number of successful attempts towards the synthesis of CeO2 nanowires with such small diameters, and the reported protocols are typically limited to low amounts. The nanowires displayed uniform shapes and sizes, high surface areas, an increased number of oxygen defects sites, and a high proportion of Ce3+/Ce4+ surface species. These features make them promising candidates for oxidation reactions. To this end, we employed the selective oxidation of aniline as a model transformation. The sub-15 nm CeO2 nanowires catalyzed the selective synthesis of nitrosobenzene (up to 98% selectivity) from aniline at room temperature using H2O2 as the oxidant. The effect of solvent and temperature during the catalytic reaction was investigated. We found that such parameters played an important role in the control of the selectivity. The improved catalytic activities observed for the sub-15 nm nanowires could be explained by: i) the uniform morphology with a typical dimension of 11 +/- 2 nm in width, which provides higher specific surface areas relative to those of conventional catalysts; ii) the significant concentration of oxygen vacancies and high proportion of Ce3+/Ce4+ species at the surface that represent highly active sites towards oxidation reactions; iii) the crystal growth along the (110) highly catalytically active crystallographic directions, and iv) the mesoporous surface which is easily accessible by liquid substrates. The results reported herein demonstrated high activities under ambient conditions, provided novel insights into selectivities, and may inspire novel metal oxide-based catalysts with desired performances. (AU)

• FAPESP's process: 14/50279-4 - Brasil Research Centre for Gas Innovation
• Grantee: Julio Romano Meneghini
• Support Opportunities: Research Grants - Research Centers in Engineering Program
• FAPESP's process: 14/09087-4 - Studies on the use of bioethanol in proton exchange membrane and solid oxide fuel cells
• Grantee: Marcelo Linardi
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 15/26308-7 - Optimization of the physicochemical properties of nano -structured materials for applications in molecular recognition, catalysis and energy conversion/storage
• Grantee: Roberto Manuel Torresi
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 15/21366-9 - HYBRID MATERIALS CONTAINING METAL NANOPARTICLES FOR CATALYTIC APPLICATIONS
• Grantee: Pedro Henrique Cury Camargo
• Support Opportunities: Regular Research Grants