Surfactant-Free Synthesis of Three-Dimensional Metallic Nanonetworks via Nanobubble-Assisted Self-Assembly

Abstract

Three-dimensional metallic nanonetworks (3D-MNWs) demonstrate unique performances across a wide range of fields, and their facile and green synthetic method is of high significance. Herein, we report a self-generated-nanobubble scaffolding strategy for the fabrication of 3D-MNWs, which employs aqua ammonia (AA) as a nanobubble reservoir and avoids the use of any surfactants or polymeric capping agents. Benefiting from the interaction between ammonia and metallic nanoparticles, finely interlocked nanonetworks (Au, Pt, Ag, and Cu) with curved geometry and abundant pores are obtained by precisely controlling the anisotropic kinetic growth using a strong reducing agent and a high concentration of AA. As a demonstration, the methanol oxidation reaction (MOR) is tested to assess the electrocatalytic performance of the Pt 3D-MNWs. The peak current of Pt 3D-MNWs reaches 152 mA/mgPt, which is 2.5 times higher than that of commercial Pt black. This unique nanobubble-assisted strategy has great potential in the basic synthetic prototype for polyporous nanomaterials.

Surfactant-free synthesis of metal and metal oxide nanomaterials: a perspective

“…71 The Pt nanonetworks exhibited excellent electrocatalytic performance towards the methanol oxidation reaction, showing the potential of the nanobubble-assisted strategy for surfactant-free synthesis of polyporous nanomaterials. 71 In addition, a surfactant-free synthesis technique based on one-step hydrothermal reduction was introduced for the synthesis of Pt nanoclusters (∼2 nm) using 2-[4-(2-hydroxyethyl)piperazin-1-yl]ethanesulfonic acid (HEPES) (as a non-toxic reducing agent); these NPs could be applied for biological imaging as well as sensing of hypochlorous acid (HClO), with advantages of fast response, high stability, and specificity. As nanoprobes, they exhibited bright blue fluorescence, high stability, and biocompatibility, while their fluorescence could be specifically quenched with hypochlorous acid by a static quenching pathway.…”

“…71 Accordingly, interlocked metallic nanonetworks could be obtained through the interactions between ammonia and metallic NPs (Cu, gold (Au), Ag, and Pt), as well as the precise control of the anisotropic kinetic growth along with the utilization of robust reducing agents and high concentration of aqua ammonia, providing nanonetworks with a curved geometry and abundant pores. 71 The Pt nanonetworks exhibited excellent electrocatalytic performance towards the methanol oxidation reaction, showing the potential of the nanobubble-assisted strategy for surfactant-free synthesis of polyporous nanomaterials. 71 In addition, a surfactant-free synthesis technique based on one-step hydrothermal reduction was introduced for the synthesis of Pt nanoclusters (∼2 nm) using 2-[4-(2-hydroxyethyl)piperazin-1-yl]ethanesulfonic acid (HEPES) (as a non-toxic reducing agent); these NPs could be applied for biological imaging as well as sensing of hypochlorous acid (HClO), with advantages of fast response, high stability, and specificity.…”

“…70 A nanobubble scaffolding self-assembly strategy was introduced for manufacturing three-dimensional (3D) metallic nanonetworks by utilizing aqua ammonia as a nanobubble reservoir, avoiding the utilization of any surfactants or polymeric capping agents. 71 Accordingly, interlocked metallic nanonetworks could be obtained through the interactions between ammonia and metallic NPs (Cu, gold (Au), Ag, and Pt), as well as the precise control of the anisotropic kinetic growth along with the utilization of robust reducing agents and high concentration of aqua ammonia, providing nanonetworks with a curved geometry and abundant pores. 71 The Pt nanonetworks exhibited excellent electrocatalytic performance towards the methanol oxidation reaction, showing the potential of the nanobubbleassisted strategy for surfactant-free synthesis of polyporous nanomaterials.…”

Boosting the Electrocatalytic Formic Acid Oxidation Activity via P-PdAuAg Quaternary Alloying

“…8,9 At present, the performance of DMAFCs is mainly restricted by the low activity and durability of the formic acid oxidation reaction (FAOR) on the anodic side. 10 The exploration of high activity and durable anodic catalysts is essential for the commercialization of DMAFCs. 11−14 Typically, the anodic decomposition of formic acid mainly follows two pathways.…”

“…Recently, fuel cells that use small organic molecules as energy sources have attracted increasing attention from industry and academic communities because of the nonrenewability of fossil fuels. , Among them, direct formic acid fuel cells (DFAFCs) are considered as one of the most promising techniques to power portable electronic devices and electric vehicles with advantages of high energy density (1740 W h kg –1 , 2086 W h L –1 ), nonflammability, − convenient storage/transportation, and low fuel crossover. , At present, the performance of DMAFCs is mainly restricted by the low activity and durability of the formic acid oxidation reaction (FAOR) on the anodic side . The exploration of high activity and durable anodic catalysts is essential for the commercialization of DMAFCs. − …”