A Rapid Synthesis Method for Au, Pd, and Pt Aerogels Via Direct Solution-Based Reduction

Burpo, F. John; Nagelli, Enoch A.; Morris, Lauren A.; McClure, Joshua P.; Ryu, Madeline Y.; Palmer, Jesse L.

doi:10.3791/57875

Cited by 6 publications

(7 citation statements)

References 11 publications

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“…Also, the H2 type hysteresis arose because the pore structure is not well-defined . This phenomenon is similar to that of noble-metal aerogels produced by previously reported methods . Moreover, the S BET values of these three aerogels are similar (∼37 m 2 g –1 in Table ), while the OAm-Au NPs have a much lower S BET of ∼0.62 m 2 g –1 , indicating that the self-supported structure of Au aerogel is helpful to maintain a much larger specific surface area and which subsequently is beneficial for the catalytic reactions.…”

Section: Resultssupporting

confidence: 74%

“…23 This phenomenon is similar to that of noble-metal aerogels produced by previously reported methods. 24 Moreover, the S BET values of these three aerogels are similar (∼37 m 2 g −1 in Table 1), while the OAm-Au NPs have a much lower S BET of ∼0.62 m 2 g −1 , indicating that the self-supported structure of Au aerogel is helpful to maintain a much larger specific surface area and which subsequently is beneficial for the catalytic reactions. The pore size distributions of A-1, -2, and -3 were analyzed, and the results demonstrate that these aerogels have a high content of mesopores (2−50 nm).…”

Section: ■ Results and Discussionmentioning

confidence: 88%

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Ligand-Exchange-Mediated Fabrication of Gold Aerogels Containing Different Au(I) Content with Peroxidase-like Behavior

Fan

Cai

et al. 2019

Chem. Mater.

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Noble-metal aerogels are emerging functional porous materials that have been applied in diverse fields. Among them, gold (Au) aerogels have displayed grand potentials in a wide range of catalytic processes. However, current fabrication methods fall short in obtaining Au gels with small ligament sizes and controlled surface valence states, which hinder the study of the underlying catalytic mechanisms. Here, a new approach of producing Au aerogels is reported. Via a two-phase ligand exchange, the long-chain ligands (oleylamine) of the as-prepared Au nanoparticles were replaced by short sulfide ions and subsequently self-assembled into three-dimensional gels. As a result, Au aerogels with small ligament sizes (ca. 3–4 nm) and tunable surface valence states are acquired. Taking the application for peroxidase mimics as an example, by correlating the surface valence with the catalytic properties, Au(I) is found to be the active site for H2O2 and substrate-binding site for 3,3′,5,5′-tetramethylbenzidine, paving a new avenue for on-target devising Au-based catalysts.

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Section: Resultssupporting

confidence: 74%

Section: ■ Results and Discussionmentioning

confidence: 88%

Ligand-Exchange-Mediated Fabrication of Gold Aerogels Containing Different Au(I) Content with Peroxidase-like Behavior

Fan

Cai

et al. 2019

Chem. Mater.

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“…Primary applications for Pt-Cu nanomaterials include electro-oxidation of methanol and ethanol [34], oxygen reduction reaction [17,35,36], and glucose detection [37]. While numerous Pt-Cu nanostructures have been demonstrated, discrete nanoparticles require post-synthesis binding into functional electrodes, and there has been limited demonstration of scalable aqueous-based synthesis of porous 3-dimensional structures.Recently rapid noble metal aerogel synthesis was demonstrated via a high concentration direct reduction approach [38,39], and salt templating was used to synthesize 2-dimensional materials [40,41]. Combining the use of high salt concentrations and salt templates, our group synthesized Pt and Pt-Pd macrobeams and porous nanomaterials from Magnus's and Vauquelin's salts and derivatives [42,43], as well as salt-templated Au-Pd and Au-Cu-Pd multi-metallic porous materials [44].…”

mentioning

confidence: 99%

“…Recently rapid noble metal aerogel synthesis was demonstrated via a high concentration direct reduction approach [38,39], and salt templating was used to synthesize 2-dimensional materials [40,41]. Combining the use of high salt concentrations and salt templates, our group synthesized Pt and Pt-Pd macrobeams and porous nanomaterials from Magnus's and Vauquelin's salts and derivatives [42,43], as well as salt-templated Au-Pd and Au-Cu-Pd multi-metallic porous materials [44].…”

mentioning

confidence: 99%

Salt-Templated Platinum-Copper Porous Macrobeams for Ethanol Oxidation

et al. 2019

Self Cite

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Platinum nanomaterials provide an excellent catalytic activity for diverse applications and given its high cost, platinum alloys and bi-metallic nanomaterials with transition metals are appealing for low cost and catalytic specificity. Here the synthesis of hierarchically porous Pt–Cu macrobeams and macrotubes templated from Magnus’s salt derivative needles is demonstrated. The metal composition was controlled through the combination of [PtCl4]2− with [Pt(NH3)4]2+ and [Cu(NH3)4]2+ ions in different ratios to form salt needle templates. Polycrystalline Pt–Cu porous macrotubes and macrobeams 10’ s–100’ s μm long with square cross-sections were formed through chemical reduction with dimethylamine borane (DMAB) and NaBH4, respectively. Specific capacitance as high as 20.7 F/g was demonstrated with cyclic voltammetry. For macrotubes and macrobeams synthesized from Pt2−:Pt2+:Cu2+ salt ratios of 1:1:0, 2:1:1, 3:1:2, and 1:0:1, DMAB reduced 3:1:2 macrotubes demonstrated the highest ethanol oxidation peak currents of 12.0 A/g at 0.5 mV/s and is attributed to the combination of a highly porous structure and platinum enriched surface. Salt templates with electrochemical reduction are suggested as a rapid, scalable, and tunable platform to achieve a wide range of 3-dimensional porous metal, alloy, and multi-metallic nanomaterials for catalysis, sensor, and energy storage applications.

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“…The physically entangled CNF-alginate hydrogels (1:1, 3% w/w) (Figure 1b) were equilibrated in a 2 M CoCl 2 -CaCl 2 solution (Co 2+ :Ca 2+ at 1:1), as shown in Figure 1c. The relatively high concentration of the salt solution was necessary to create a sufficiently high concentration gradient to drive the diffusion of ions into the gel matrix [79,80]. The divalent calcium ions served as ionic crosslinkers between the carboxylate groups on both the CNF and alginate biopolymers.…”

Section: Cnf-alginate-cobalt Aerogel Synthesismentioning

confidence: 99%

Cellulose Nanofiber–Alginate Biotemplated Cobalt Composite Multifunctional Aerogels for Energy Storage Electrodes

Zhang,

Trackey,

Verma

et al. 2023

Gels

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Tunable porous composite materials to control metal and metal oxide functionalization, conductivity, pore structure, electrolyte mass transport, mechanical strength, specific surface area, and magneto-responsiveness are critical for a broad range of energy storage, catalysis, and sensing applications. Biotemplated transition metal composite aerogels present a materials approach to address this need. To demonstrate a solution-based synthesis method to develop cobalt and cobalt oxide aerogels for high surface area multifunctional energy storage electrodes, carboxymethyl cellulose nanofibers (CNF) and alginate biopolymers were mixed to form hydrogels to serve as biotemplates for cobalt nanoparticle formation via the chemical reduction of cobalt salt solutions. The CNF–alginate mixture forms a physically entangled, interpenetrating hydrogel, combining the properties of both biopolymers for monolith shape and pore size control and abundant carboxyl groups that bind metal ions to facilitate biotemplating. The CNF–alginate hydrogels were equilibrated in CaCl2 and CoCl2 salt solutions for hydrogel ionic crosslinking and the prepositioning of transition metal ions, respectively. The salt equilibrated hydrogels were chemically reduced with NaBH4, rinsed, solvent exchanged in ethanol, and supercritically dried with CO2 to form aerogels with a specific surface area of 228 m2/g. The resulting aerogels were pyrolyzed in N2 gas and thermally annealed in air to form Co and Co3O4 porous composite electrodes, respectively. The multifunctional composite aerogel’s mechanical, magnetic, and electrochemical functionality was characterized. The coercivity and specific magnetic saturation of the pyrolyzed aerogels were 312 Oe and 114 emu/gCo, respectively. The elastic moduli of the supercritically dried, pyrolyzed, and thermally oxidized aerogels were 0.58, 1.1, and 14.3 MPa, respectively. The electrochemical testing of the pyrolyzed and thermally oxidized aerogels in 1 M KOH resulted in specific capacitances of 650 F/g and 349 F/g, respectively. The rapidly synthesized, low-cost, hydrogel-based synthesis for tunable transition metal multifunctional composite aerogels is envisioned for a wide range of porous metal electrodes to address energy storage, catalysis, and sensing applications.

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A Rapid Synthesis Method for Au, Pd, and Pt Aerogels Via Direct Solution-Based Reduction

Cited by 6 publications

References 11 publications

Ligand-Exchange-Mediated Fabrication of Gold Aerogels Containing Different Au(I) Content with Peroxidase-like Behavior

Ligand-Exchange-Mediated Fabrication of Gold Aerogels Containing Different Au(I) Content with Peroxidase-like Behavior

Salt-Templated Platinum-Copper Porous Macrobeams for Ethanol Oxidation

Cellulose Nanofiber–Alginate Biotemplated Cobalt Composite Multifunctional Aerogels for Energy Storage Electrodes

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