In situ Tracking the Constrained Reconstruction of Cu3Pd@SiO2 Nanoparticles Driven by Redox Atmospheres

Abstract Endowed with flexible surface coordination and synergetic electronic status, bimetallic particles serve as promising heterogeneous catalysts as their microstructures evolved sensitively to the treatment atmospheres, whereas knowledge of dynamic manners is less. Herein, utilizing environmental transmission electron microscopy (ETEM), the reconstructions of Cu 3 Pd particles in oxidization/reduction atmospheres were explored at atomic scale. Specifically, bare Cu 3 Pd particles went through a phase separation of CuO x and PdO x during in situ oxidation, and subsequent agglomeration after H 2 reduction. While protected in a silica shell, the confined Cu 3 Pd particles were oxidized into Cu 1.5 Pd 0.5 O 2 phase after air calcination and subsequently restructured into versatile configurations during H 2 reduction. Specifically, hollow Cu 3 Pd alloy architecture with Pd enriched layer near surface as reduced at 200 °C. Further rising 400 to 600 °C, it yielded disordered Cu 3 Pd alloys with slightly Pd atoms enrichment at outmost surface. The dynamical behaviors of single Cu 1.5 Pd 0.5 O 2 particle during in situ reduction have been visualized in ETEM, wherein a series of deformation, elongation and rotation is involved during the hollow architecture firstly formation, and then vanished into a Cu 3 Pd solid solution nanoparticle. The tunable microstructures of Cu 3 Pd@SiO 2 driven by redox atmospheres demonstrate efficient approach for precisely regulating the chemical environments of constrained bimetallic nanocatalysts.