The synthesis of inorganic nanocrystals with controllable morphologies is a key goal in modern materials chemistry and has attracted substantial interest in recent years. [1] The shape-and size-dependant properties of nanoparticles are well established and a fine degree of control over size and morphology can lead to the formation of materials with specific chemical and physical properties. [2] For example, anisotropic morphologies such as branched nanocrystals that include bipods, tripods, tetrapods, and multipods show great promise in many applications, as they often exhibit unique electronic, magnetic, photonic, and catalytic properties. [2] Palladium is used extensively in industry as a heterogeneous catalyst with significant focus on the low temperature catalytic reduction of automobile emissions and in Suzuki, Heck, and Stille coupling reactions. [3a,b] For catalytically active materials, anisotropic shape can greatly enhance performance by increasing surface area and selectively, exposing specific (high-index) crystal facets. [3a,b] For example, Meng et al. produced anisotropic palladium nanothorns that showed increased catalytic performance for the oxidation of formic acid. [3c] Palladium is also a promising material for hydrogen storage and gas-sensing applications, as it absorbs hydrogen in high concentrations. [4] Nanostructured palladium also shows potential as a surface-enhanced Raman spectroscopy (SERS) substrate, where the spectral range and enhancement intensity have been shown to be morphology dependent. [5] Thus, the development of synthetic methods for the formation of palladium nanoparticles with controlled morphologies, particularly pod-like structures, is important for a range of future applications.
Palladium nanoparticles have previously been synthesized using a number of different methods. [6][7][8] Choo et al. produced isotropic morphologies through the controlled reduction of PdCl 2 . [6] Xiong et al. formed anisotropic palladium structures including nanobars, nanorods, triangular, and hexagonal particles using ethylene glycol as the reductant. [7] Teng et al. showed the evolution of palladium nanoparticles into ultrathin nanowires. [8] COMMUNICATION