In situ growth of metallic Ag-0 intercalated CoAl layered double hydroxides as efficient electrocatalysts for the oxygen reduction reaction in alkaline solutions

摘要

Metallic Ag-0 intercalated CoAl-layered double hydroxides (CoAl LDHs) have been successfully synthesized in situ through a simple redox process with ethylene glycol (EG) and triethanolamine (TEOA). The Ag(CN)(2)(-) anion-exchanged precursor was reduced by EG to form metallic Ag-0. Furthermore, the effect of TEOA on confining the particle size of Ag-0 was demonstrated. The oxygen reduction reaction (ORR) property of metallic Ag-0 intercalated CoAl LDHs was examined in alkaline aqueous solution. A typical sample synthesized by the addition of TEOA for 180 min exhibited excellent ORR catalytic activity with a high current density of 5.5 mA cm(-2) at 0.2 V (vs. a reversible hydrogen electrode (RHE)) and good stability. Koutecky-Levich (K-L) calculations and rotating ring-disk electrode (RRDE) measurements further revealed that the ORR of the as-prepared catalyst proceeded mainly via an almost ideal four-electron transfer process. The enhanced electrocatalytic activity was ascribed to the intercalated Ag-0, confined nanoparticle size and the expanded interlayer space, which effectively facilitate the reactant transfer and electron migration.