Pt-Co Alloy Nanoparticles on a γ-Al2 O3 Support: The Synergistic Effect between Isolated Electron-Rich Pt and Co for Automotive Exhaust Purification.

Invited for this month's cover is the group of Dr. Katsutoshi Sato and Prof. Dr. Katsutoshi Nagaoka (Kyoto University) and collaborators at Oita and Kyushu Universities. The cover picture shows the proposed mechanism for automotive exhaust purification over a Pt-Co alloy nanoparticle catalyst with an extremely low Pt/Co molar ratio. In the catalyst, the isolated electron-rich Pt atoms are present on the surface of the nanoparticles and play an important role in NOx capture and activation, which are important elementary steps in exhaust purification. Read the full text of the article at 10.1002/cplu.201800542.

Pt-Co Alloy Nanoparticles on a γ-Al2 O3 Support: Synergistic Effect between Isolated Electron-Rich Pt and Co for Automotive Exhaust Purification.

There is interest in minimizing or eliminating the use of Pt in catalysts by replacing it with more widely abundant and cost-effective elements. The alloying of Pt with non-noble metals is a potential strategy for reducing Pt use because interactions between Pt and non-noble metals can modify the catalyst structure and electronic properties. Here, a γ-Al2 O3 -supported bimetallic catalyst [Pt(0.1)Co(1)/Al2 O3 ] was prepared which contained 0.1 wt % Pt and 1 wt % Co and thus featured an extremely low Pt : Co ratio (<1 : 30 mol/mol). The Pt and Co in this catalyst formed alloy nanoparticles in which isolated electron-rich Pt atoms were present on the nanoparticle surface. The activity of this Pt(0.1)Co(1)/Al2 O3 catalyst for the purification of automotive exhaust was comparable to the activities of 0.3 and 0.5 wt % Pt/γ-Al2 O3 catalysts. Electron-rich Pt and metallic Co promoted activation of NOx and oxidization of CO and hydrocarbons, respectively. This strategy of tuning the surrounding structure and electronic state of a noble metal by alloying it with an excess of a non-noble metal will enable reduced noble metal use in catalysts for exhaust purification and other environmentally important reactions.

A Synthetic Pseudo-Rh: NOx Reduction Activity and Electronic Structure of Pd-Ru Solid-solution Alloy Nanoparticles.

Rh is one of the most important noble metals for industrial applications. A major fraction of Rh is used as a catalyst for emission control in automotive catalytic converters because of its unparalleled activity toward NOx reduction. However, Rh is a rare and extremely expensive element; thus, the development of Rh alternative composed of abundant elements is desirable. Pd and Ru are located at the right and left of Rh in the periodic table, respectively, nevertheless this combination of elements is immiscible in the bulk state. Here, we report a Pd-Ru solid-solution-alloy nanoparticle (PdxRu1-x NP) catalyst exhibiting better NOx reduction activity than Rh. Theoretical calculations show that the electronic structure of Pd0.5Ru0.5 is similar to that of Rh, indicating that Pd0.5Ru0.5 can be regarded as a pseudo-Rh. Pd0.5Ru0.5 exhibits better activity than natural Rh, which implies promising applications not only for exhaust-gas cleaning but also for various chemical reactions.