Gold Nanoparticle Morphology Adjusted As High-Performance Catalyses in Supergiant Dispersant

The deliberate engineering of environmentally benign and sustainable catalytic processes involving anisotropic gold nanoparticles (AuNPs) presents a formidable challenge. In this investigation, a novel green synthesis of anisotropic AuNPs is achieved by reducing an Au precursor through the oxidation of anionic superdispersant mega-polysaccharides known as sacran, as confirmed by XPS techniques. The reduction potential influences the resulting Au shapes, with differences observed at higher sacran concentrations or higher reduction potentials. The use of monodispersed seeds, along with the assistance of iodide anions, induces high uniform anisotropic growth. Under optimized conditions, the occupancy of triangular AuNPs (AuNTs) with uniform sizes and morphologies reached an impressive ∼92% area ratio. Additionally, an alternative synthesis condition leads to the formation of decahedral AuNPs (AuNDs). Notably, the AuNTs exhibit exceptional catalytic performance towards 4-nitrophenol (4-NP) with a specific rate constant (k) of 2.90×10³ s⁻¹g⁻¹, which is 3.4 times higher than that of most reported AuNPs under conventional capping agents. The catalytic activity remains satisfactory after multiple reaction cycles, highlighting the sustainability of AuNTs within the superdispersant mega-saccharides medium. Furthermore, the AuNTs catalyst demonstrates both an excellent conversion rate and selectivity for the catalytic reduction of a series of chloro-substituted nitroarenes.