Catalytic performance and mechanism of N-CoTi@CoTiO3 catalysts for oxygen reduction reaction

Alternative non-precious metal catalysts with comparable oxygen reduction reaction activity and durability to Pt-based catalysts are highly desirable for the development of fuel cell. Herein, we report a novel and efficient non-precious electrocatalyst N-CoTi@CoTiO3/C featuring an unusual composite oxide layer on the surface of CoTi alloy nanoparticles, which was investigated using probe-corrected scanning transmission electron microscopy, electron energy-loss spectroscopy, and density functional theory calculations. The N-CoTi@CoTiO3/C catalyst shows superior catalytic performance for oxygen reduction reactions (ORR) in alkaline solutions, with comparable onset potential, half-wave potential to commercial Pt/C and specific activity 1.5 times as high as commercial Pt/C at 0.70 V. Theoretical calculations demonstrate that the surface oxide layer polarization effect caused by the intermetallic CoTi core plays a key role in the high ORR activity of N-CoTi@CoTiO3/C. The enhancement of ORR activity and durability of catalyst by the surface polarization provides a versatile strategy for tuning the catalytic performance of non-noble electrocatalysts. (C) 2015 Elsevier Ltd. All rights reserved.