Precise construction of Pd superstructures with modulated defect properties for solar-driven organic transformation

Abstract

Precisely controlling the spatial arrangement of nanostructures offers unique opportunities for tuning physical and chemical properties; however, it remains a great challenge due to the lack of effective synthetic methods. Herein, we present a wet-chemistry strategy for the synthesis of three-dimensional (3D) Pd superstructures (Pd SSs) by manipulating the growth kinetics. The strategy consists of two steps including (1) the formation of a tetrahedron-shaped Pd nanocrystal core and (2) the growth of four legs on each tip of the core. Interestingly, each leg can be built from one, two, or three arrowhead-like Pd nanocrystals. Moreover, Pd SSs exhibit unique defect-induced modulated structure properties due to the existence of periodic Pd vacancies, which can provide active sites for reactant molecule adsorption and activation. The Pd SSs exhibit excellent catalytic performance toward the oxidation of o-phenylenediamine (OPDA) under visible and near-infrared (NIR) light illumination. Both theoretical and experimental results demonstrate that the superior photocatalytic activity of Pd SSs is derived from the well-ordered 3D architecture, unique modulated defect properties, high-index facets, and large local electric field enhancement. This research sheds new light on the rational design and precise construction of 3D nanostructures, with potential applications in the fields of catalysis, nanotechnology, and biotechnology.