Improved Alcohol Oxidation through Combined Effects of Tensile Lattice Strain and Twin Defects in Core-Shell Electrocatalysts

The direct alcohol fuel cells (DAFCs) rely on alcohol oxidation reactions (AORs) to produce electricity, which require catalysts with optimized electronic structure to accelerate the sluggish AORs. Herein, an epitaxial growth of Pd layer onto the pentatwinned Au@Ag core-shell nanorods (NRs) is reported to synthesize highly strained Au@AgPd core-shell NRs. The tensile strain in the AgPd shell of the Au@AgPd nanorods (NRs) arises not only from the core-shell lattice mismatch but also from twinning and lattice distortion occurring at the five twinned boundaries present in the structure. Theoretical simulations prove that the presence of tensile strains in the AgPd layer leads to a significant upward shift of the d-band center of the Pd site toward the Fermi level which remarkably changes the adsorption energy of alcohols on the surface. Highly strained Au@AgPd NRs show exceptional mass activities in electrochemical oxidation of biomass-derived alcohols (ethylene glycol, ethanol, and glycerol) reaching up to 18.66, 15.6, and 7.90 A mgpd-1, respectively. These values are 23.3, 23.6, and 23.2 times higher than commercial Pd/C catalysts. This strain engineering strategy set the platform for the design and synthesis of highly efficient and versatile catalysts for the construction of high-performance DAFCs. Using controlled galvanic-replacement reaction highly strained Au@AgPd core-shell nanorods (NRs) are prepared, which shows a 23-times increase in electrocatalytic mass activity for alcohol oxidation compared to commercial Pd/C, attributed as lattice mismatch-induced tensile strain and lattice distortion at the five twinned boundaries in the AgPd shell. image