New nanostructured earth abundant metal catalysts rival platinum on a weight basis; diesel emissions treatment
A development in catalysis research by academics at the Universities of St Andrews and Newcastle could lead to new systems to treat diesel emissions. Catalysts are typically metallic nanoparticles—often platinum group metals—that are finely deposited upon a substrate. The activity and durability of the catalyst critically depends upon the interaction of the particles with the substrate. In recent years a team at the University of St Andrews has been exploring metal nanoparticles prepared by redox exsolution at the surface of perovskite oxides and have shown these structures to enable new dimensions in catalysis and energy conversion and storage technologies owing to their socketed, well-anchored structure. (In redox exsolution, metal particles of controlled size are allowed to emerge at the surface of an oxide support under reducing atmosphere.)
Now, working closely with researchers at Newcastle University, the researchers have demonstrated that—contrary to general belief—exsolved particles do not re-dissolve back into the underlying perovskite upon oxidation. Instead, they may remain pinned to their initial locations, and can then undergo further chemical transformations to alter their composition, structure and functionality significantly, while preserving their initial spatial arrangement. This is referred to as “chemistry at a point”.
The utility of structures prepared via this concept has been demonstrated in relation to exhaust clean-up from diesel emissions, oxidizing CO and NO simultaneously over hundreds of hours of operation. The concept represents a step-change in the design of earth-abundant metal catalysts rivaling platinum for reactions of key practical importance, on a weight basis, and also at temperatures relevant to exhaust emissions. The approach enables the design of compositionally diverse confined oxide particles with superior stability and catalytic reactivity.
The findings are published in the journal Nature Communications.
This concept ‘chemistry at a point’ enables the design of compositionally-diverse confined oxide particles with superior stability and catalytic reactivity wide applicability in clean energy processes and environmental remediation. In 2015 the Government estimated that exposure to NOx and particulate matter emissions from diesel engines lead to around 52,000 additional deaths in the UK; the findings of the research has far-reaching implications for the future of clean diesel and air pollution.—Professor John Irvine from the School of Chemistry at St Andrews
Dragos Neagu, Evangelos I. Papaioannou, Wan K. W. Ramli, David N. Miller, Billy J. Murdoch, Hervé Ménard, Ahmed Umar, Anders J. Barlow, Peter J. Cumpson, John T. S. Irvine & Ian S. Metcalfe (2017) “Demonstration of chemistry at a point through restructuring and catalytic activation at anchored nanoparticles” Nature Communications 8, Article number: 1855 doi: 10.1038/s41467-017-01880-y