Morphological Characteristics of Gold Nanowires and Nanoparticles: Structure Elucidation and Reactivity Toward Water-gas Shift Reaction

Irradiation of γ-ray to FSM-16 encapsulated HAuCl4, synthesized via chemical vapor deposition, led to the formation of Au nanowires (2−10 nm diameter and 17−147 nm length). Contrarily, reductive carbonylation of impregnated HAuCl4 with FSM-16 using CO (200 torr)/water (20 torr) for 2 h, followed by irradiation with a high-pressure Hg lamp at 300 K for 36 h, resulted in the formation of Au nanoparticles (circular; 8−75 nm diameter). These catalysts have been characterized by XRD, N2-sorpitometry, TEM, UV−vis-DRS, CO-FTIR spectroscopy, and then tested for water-gas shift reaction (WGSR) under feeding conditions of PCO = 60 torr and PH2O = 5 torr. Evidently, Au nanowires exhibited higher activity (3 times) than Au nanoparticles. It has been shown that the activity depends on Au geometry rather than structural characteristics, such as surface area. In-situ FTIR CO adsorption and UV−vis-DRS evidenced major changes on the surface properties of Au nanowires in exposing different oxidation states as well as induc...