Rational design of efficient transition metal core-shell electrocatalysts for oxygen reduction and evolution reactions.

Ag can form core-shell structures with other non-precious transition metals, which is a promising candidate as an efficient and cost-effective electrocatalyst to replace Pt and RuO 2 for oxygen reduction and evolution reactions (ORR and OER) in fuel cells and metal-air batteries. In this paper, polyicosahedral (plh) Ag 32 X 6 (X = 3d transition metals) core-shell structures are calculated systematically by the density functional theory (DFT) method to predict their electrocatalytic activities for ORR and OER. It is found that the strain on the outer shell of the core-shell structures can be an intrinsic descriptor that describes the bifunctional catalytic activities of the catalysts. A higher compressive strain leads to more positive charge on the surface of the shell and consequently higher catalytic activities. The results provide a theoretical base for the rational design and screening of the Ag-based core-shell catalysts for clean energy conversion and storage.