Electronically Modified Atomic Sites Within a Multicomponent Co/Cu Composite for Efficient Oxygen Electroreduction

摘要

Rational design of cost-effective and active electrocatalysts is an essential step toward the large-scale realization of hydrogen fuel cells and metal-air batteries. Its success requires a drastic improvement in the kinetics of the cathodic oxygen reduction reaction (ORR). Herein, a novel ORR catalyst formed by encapsulating thin Cu layer decorated Co nanoparticles inside graphitic carbon layers that are embedded with abundant Co-N-x and Cu-N-x atomic sites (denoted as SA-CoCu@Cu/CoNP), is reported. The multicomponent SA-CoCu@Cu/CoNP composite exhibits a remarkable ORR catalytic activity, exceptional stability, and excellent methanol tolerance in alkaline media, outperforming the commercial platinum carbon under identical testing conditions and also being active in acidic media. The excellent ORR catalytic performance is ascribed to the modified electronic structure of the Co-N-x active sites due to an electron donating effect from the embedded nanoparticles and the nearby Cu-N-x species, as revealed by X-ray spectroscopic results and density functional theory computations. Moreover, the effective role of Cu-N-x sites in suppressing the peroxide formation during ORR is also identified, endowing the resultant catalyst a prolonged stability and enhanced efficiency that are beneficial for practical applications.