Abstract
As a profitable product from CO(2) electroreduction, HCOOH holds economic viability only when the selectivity is higher than 90% with current density (j) over -200.0 mA cm(-2). Herein, Bi@Sn core-shell nanoparticles (Bi core and Sn shell, denoted as Bi@Sn NPs) are developed to boost the activity and selectivity of CO(2) electroreduction into HCOOH. In an H-cell system with 0.5 m KHCO(3) as electrolyte, Bi@Sn NPs exhibit a Faradaic efficiency for HCOOH (FE(HCOOH)) of 91% with partial j for HCOOH (j (HCOOH)) of -31.0 mA cm(-2) at -1.1 V versus reversible hydrogen electrode. The potential application of Bi@Sn NPs is testified via chronopotentiometric measurements in the flow-cell system with 2.0 m KHCO(3) electrolyte. Under this circumstance, Bi@Sn NPs achieve an FE(HCOOH) of 92% with an energy efficiency of 56% at steady-state j of -250.0 mA cm(-2). Theoretical studies indicate that the energy barrier of the potential-limiting step for the formation of HCOOH is decreased owing to the compressive strain in the Sn shell, resulting in the enhanced catalytic performance.