Engineering porous Pd-Cu nanocrystals with tailored three-dimensional catalytic facets for highly efficient formic acid oxidation

Rational synthesis of bi- or multi-metallic nanomaterials with both dendritic and porous features is appealing yet challenging. Herein, with the cubic Cu 2 O nanoparticles composed of ultrafine Cu 2 O nanocrystals as a self-template, a series of Pd-Cu nanocrystals with different morphologies ( e.g. , aggregates, porous nanodendrites, meshy nanochains and porous nanoboxes) are synthesized through simply regulating the molar ratio of the Pd precursor to the cubic Cu 2 O, indicating that the galvanic replacement and Kirkendall effect across the alloying process are well controlled. Among the as-developed various Pd-Cu nanocrystals, the porous nanodendrites with both dendritic and hollow features show superior electrocatalytic activity toward formic acid oxidation. Comprehensive characterizations including three-dimensional simulated reconstruction of a single particle and high-resolution transmission electron microscopy reveal that the surface steps, defects, three-dimensional architecture, and the electronic/strain effects between Cu and Pd are responsible for the outstanding catalytic activity and excellent stability of the Pd-Cu porous nanodendrites. An innovative strategy is developed to prepare porous Pd-Cu nanocrystals with engineered morphology and highly exposed three-dimensional catalytic facets, which demonstrate considerably improved activity toward formic acid oxidation.