Shape Tailoring of Nonconventional Ni-Pt Nanoparticles through a PDDA-Polyol Method

Controlling particle morphology is an effective strategy to tune the catalytic behavior of bimetallic nanostructures. Here, we report a simple PDDA-assisted polyol approach to induce systematic shape modulation in nickel-platinum nanostructures. By adjusting the concentration of poly-(diallyldimethylammonium chloride) (PDDA) and the relative Ni/Pt precursor ratio, a gradual morphological evolution was observed, ranging from truncated octahedra to stepped pyramidal and branched flower-like architectures. High-resolution transmission electron microscopy revealed that low PDDA contents promote the development of stepped growth features, whereas increasing PDDA concentrations favor the formation of more complex branched assemblies, consistent with a flocculation-assisted growth pathway. Variations in the Ni/Pt precursor ratio were found to influence compositional trends and surface-related structural characteristics. Catalytic tests using the reduction of 4-nitrophenol as a model reaction showed enhanced activity for these novel nanostructures. Overall, this study highlights the versatility of PDDA as a polymeric growth modulator and emphasizes morphology control as a practical strategy for designing efficient Ni-Pt-based nanocatalysts through a simple wet-chemical approach.