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Direct and continuous strain control of catalysts with tunable battery electrode materials

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Science  25 Nov 2016:
Vol. 354, Issue 6315, pp. 1031-1036
DOI: 10.1126/science.aaf7680

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Tuning nanoparticle strain

The catalytic activity of metals in heterogeneous catalysts can be altered by applying strain, which changes the crystalline lattice spacing and modifies the metal's electronic properties. Wang et al. show how particles of cobalt oxide, a positive electrode for lithium batteries, can expand or contract with charging and transfer strain to adsorbed platinum nanoparticles. For the oxygen reduction reaction used in fuel cells, compressive strain boosted activity by 90%, and tensile strain decreased it by 40%.

Science, this issue p. 1031

Abstract

We report a method for using battery electrode materials to directly and continuously control the lattice strain of platinum (Pt) catalyst and thus tune its catalytic activity for the oxygen reduction reaction (ORR). Whereas the common approach of using metal overlayers introduces ligand effects in addition to strain, by electrochemically switching between the charging and discharging status of battery electrodes the change in volume can be precisely controlled to induce either compressive or tensile strain on supported catalysts. Lattice compression and tension induced by the lithium cobalt oxide substrate of ~5% were directly observed in individual Pt nanoparticles with aberration-corrected transmission electron microscopy. We observed 90% enhancement or 40% suppression in Pt ORR activity under compression or tension, respectively, which is consistent with theoretical predictions.

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