(Invited) Controlling Multi-Component Colloidal Nanocrystal Surface and Interface for Enhanced Electrocatalysis

Abstract

Nanocrystals with well-controlled surface and interface structures as well as multi-component interactions present new opportunities to tune and optimize nanocatalyst properties for many energy and environmental applications. In this talk, I will highlight the colloidal approach for the synthesis of well-defined nanocrystals with these surface and interface features for enhanced electrocatalysis. These multicomponent nanocrystals play critical roles in maximizing the benefit of oxygen-mediated energy conversion reactions: oxygen reduction reaction (ORR) for fuel cells and oxygen evolution reaction (OER) for water electrolyzer. The first example is M-Pt (M=non-precious metals) core-shell nanocrystals within which desirable/undesirable interfaces between non-precious metal M core and precious metal Pt shell are identified by density functional theory (DFT) calculations and are practically balanced by nanocrystal synthesis. The optimized core-shell nanocrystals exhibit favorable interfacial interaction at nanometer scale through properly coupled electronic and strain effects, leading to an enhanced electrocatalytic efficiency toward oxygen reduction reaction (ORR). In second example, we take advantage of single-atom Co's synergy with various oxide support for electrochemical oxygen evolution reaction (OER). By choosing the proper oxide supporting nanocrystals, single atom Co conversion and stabilization at high valence OER active site can be controlled through its interaction with supporting materials. The relevant theoretical calculation, controlled synthesis and structural/catalytic characterization of nanocrystals will be discussed.