O 2 activation by core-shell Ru 13 @Pt 42 particles in comparison with Pt 55 particles: a DFT study.

The reaction of O 2 with a Ru 13 @Pt 42 core-shell particle consisting of a Ru 13 core and a Pt 42 shell was theoretically investigated in comparison with Pt 55 . The O 2 binding energy with Pt 55 is larger than that with Ru 13 @Pt 42 , and O-O bond cleavage occurs more easily with a smaller activation barrier ( E a ) on Pt 55 than on Ru 13 @Pt 42 . Protonation to the Pt 42 surface followed by one-electron reduction leads to the formation of an H atom on the surface with considerable exothermicity. The H atom reacts with the adsorbed O 2 molecule to afford an OOH species with a larger E a value on Pt 55 than on Ru 13 @Pt 42 . An OOH species is also formed by protonation of the adsorbed O 2 molecule, followed by one-electron reduction, with a large exothermicity in both Pt 55 and Ru 13 @Pt 42 . O-OH bond cleavage occurs with a smaller E a on Pt 55 than on Ru 13 @Pt 42 . The lower reactivity of Ru 13 @Pt 42 than that of Pt 55 on the O-O and O-OH bond cleavages arises from the presence of lower energy in the d-valence band-top and d-band center in Ru 13 @Pt 42 than in Pt 55 . The smaller E a for OOH formation on Ru 13 @Pt 42 than on Pt 55 arises from weaker Ru 13 @Pt 42 -O 2 and Ru 13 @Pt 42 -H bonds than the Pt 55 -O 2 and Pt 55 -H bonds, respectively. The low-energy d-valence band-top is responsible for the weak Ru 13 @Pt 42 -O and Ru 13 @Pt 42 -OH bonds. Thus, the low-energy d-valence band-top and d-band center are important properties of the Ru 13 @Pt 42 particle.