Electrocatalysis of Oxygen Reduction on Te-Modified Platinum Stepped Crystal Surfaces

Te-modified platinum single-crystal surfaces in the [011̅] zone have been used as model electrocatalysts for oxygen reduction reaction (ORR). The results clearly show that (1) except for Pt(111), all other electrodes display enhanced ORR activity when Te is deposited on the surface; (2) the intrinsic ORR activity for Pt(hkl) decreases in the order of Pt(322) > Pt(755) > Pt(977) > Pt(111) > Pt(311) > Pt(100), while the enhancement factor for ORR with Te modification decreases in the order of Pt(100) > Pt(311) > Pt(977) > Pt(755) > Pt(322); (3) metallic Te and its charge transfer to Pt as well as the consequent lower d-band center and OHad binding energy are probably the reasons for the enhanced electrocatalysis for ORR with Te modification; and (4) the inhibition of Te at Pt(111) as well as the smaller extent for the enhancement of Te at Pt(S)-[n(111) × (100)] with longer terraces in the kinetic region for ORR are a result of partial oxidation of Te. The weaker electronic interaction of Te with the Pt substrate is probably the origin of its facile oxidation at lower potential. Our results imply that modification of Pt with species that can transfer electrons to Pt may be an efficient strategy to enhance the ORR activity.