Template-dealloying synthesis of ultralow density Au foams with bimodal porous structure

Abstract

Noble metallic foams with low density are desirable in high energy-density physical experiments. In this study, Au foams with ultralow density were successfully synthesized from a template-dealloying approach. Microspherical polystyrene (PS) was employed as the sacrificial template. Au and Ag nanoparticles were sequentially coated onto the PS surface from a three-step deposition process. Cylindrical PS/Au/Ag monoliths were formed by filter-casting of the nanoparticle coated PS suspension. The templates were removed and Au–Ag alloy foams were generated after calcination at 400 °C. Self-supported Au foams with bimodal porous structure were produced by dealloying of the less noble Ag component. Au foam with density as low as 0.36 g cm⁻³ can be achieved, which demonstrates high surface area of 23.6 m² g⁻¹ and pore volume of 0.15 m³ g⁻¹.