Synthesis of very highly dispersed platinum catalysts supported on carbon xerogels by the strong electrostatic adsorption method

Lambert, Stéphanie D.; Job, Nathalie; D’Souza, Lawrence; Pereira, M.F.R.; Pirard, René; Heinrichs, Benoı̂t; Figueiredo, José L.; Pirard, Jean-Paul; Regalbuto, John R.

doi:10.1016/j.jcat.2008.10.014

Cited by 132 publications

(82 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…TEM images of several catalysts prepared using the above-mentioned methods are presented in Figure 3. In each case, the support is a raw carbon xerogel (PZC ~9), with a pore size of around 70 nm, and the Pt precursor is H2PtCl6, but it is worth noticing that very similar results were found with carbon xerogels oxidized in HNO3 as the support and [Pt(NH3)4](NO3)2 as the precursor [20,23]; in that case, since the PZC of the oxidized carbon xerogel was equal to 2.4, impregnation was performed under basic conditions (initial pH = 12.5, i.e., optimized conditions for the [Pt(NH3)4](NO3)2/oxidized carbon xerogel pair).…”

Section: Resultsmentioning

confidence: 84%

“…We do not report detailed results here, but globally, the only effect of metal deposition on the pore texture of the carbon xerogel is a decrease of the specific surface area, SBET, certainly due to a partial blocking of the micropores by nm-sized Pt particles. Depending on the loading, the loss of specific surface area, reported per mass of carbon, ranges from 100 to 200 m 2 /g [20,21]. The meso-macropores remain unchanged, both in terms of pore size and pore volume, compared to the pristine carbon xerogel support.…”

Section: Resultsmentioning

confidence: 99%

“…On the contrary, at a pH higher than the PZC of the support, the adsorption of cations (e.g., [Pt(NH3)4] 2+ ) is enhanced. This property can be exploited by the so-called "strong electrostatic adsorption" (SEA) method [11,20], which consists of maximizing the electrostatic interactions, so as to adsorb the maximum amount of Pt at the support surface. The PZC of the support can be measured by the method of Park and Regalbuto (equilibrium pH at high loading, EpHL) [11].…”

Section: Strong Electrostatic Adsorptionmentioning

confidence: 99%

“…Alternatively, one can, of course, thus imagine re-using the residual solution by re-adjusting its pH and concentration at the required values [22]. Indeed, as long as the concentration of the H2PtCl6 solution remains higher than ~4 mmol/L, the Pt uptake remains constant [20]. Therefore, another catalyst was prepared by multiple SEA (M-SEA), but the concentration of the initial impregnation solution was higher, then re-used several times.…”

Section: Multiple Strong Electrostatic Adsorptionmentioning

confidence: 99%

See 3 more Smart Citations

Design of Pt/Carbon Xerogel Catalysts for PEM Fuel Cells

et al. 2015

View full text Add to dashboard Cite

Abstract:The design of efficient catalytic layers of proton exchange membrane fuel cells (PEMFCs) requires the preparation of highly-loaded and highly-dispersed Pt/C catalysts. During the last few years, our work focused on the preparation of Pt/carbon xerogel electrocatalysts, starting from simple impregnation techniques that were further optimized via the strong electrostatic adsorption (SEA) method to reach high dispersion and a high metal weight fraction. The SEA method, which consists of the optimization of the precursor/support electrostatic impregnation through an adequate choice of the impregnation pH with regard to the support surface chemistry, leads to very well-dispersed Pt/C samples with a maximum 8 wt.% Pt after drying and reduction under H2. To increase the metal loading, the impregnation-drying-reduction cycle of the SEA method can be repeated several times, either with fresh Pt precursor solution or with the solution recycled from the previous cycle. In each case, a high dispersion (Pt particle size ~3 nm) is obtained. Finally, the procedure can be simplified by combination of the SEA technique with dry impregnation, leading to no Pt loss during the procedure.

show abstract

Section: Resultsmentioning

confidence: 84%

Section: Resultsmentioning

confidence: 99%

Section: Strong Electrostatic Adsorptionmentioning

confidence: 99%

Section: Multiple Strong Electrostatic Adsorptionmentioning

confidence: 99%

See 2 more Smart Citations

Design of Pt/Carbon Xerogel Catalysts for PEM Fuel Cells

et al. 2015

View full text Add to dashboard Cite

show abstract

“…The homogeneously alloyed metal nanoparticles have a narrow size distribution around 1 nm. In the developed method, positively charged metal-amine complex precursors were deposited onto negatively charged surface of silica support through strong electrostatic adsorption (SEA) [8,9], and then reduced by H 2 at an elevated temperature to give supported uniform ultrasmall alloyed nanoparticles (Fig. 1a).…”

mentioning

confidence: 99%

Amine facilitates the synthesis of silica-supported ultrasmall bimetallic nanoparticles

Liu

2018

Sci. China Mater.

View full text Add to dashboard Cite

Supported catalysts based on metal nanoparticles are a class of widely used heterogeneous catalysts in industry. The catalytic performances of supported metal catalysts are highly determined by many parameters of metal nanoparticles such as their particle size, composition, surface structure and also interfacial interaction with supports [1]. Supported metal catalysts are commonly prepared by depositing metal precursors on high-surface area supports through various methods such as impregnation (IMP), co-precipitation (CP), and depositionprecipitation (DP), followed by thermal or chemical reduction of the metal precursors deposited thereon to form supported metal nanoparticles.The difficulty for conventional methods to prepare high-quality supported metal nanoparticles with uniform particle size and composition mainly lies in the following two aspects: 1) The interaction between metal precursors and supports is not strong enough to prevent their sintering during the post thermal or chemical reduction processes; 2) The deposition of metal precursors is not homogenous so that the phase separation often occurs after the reducing treatment. By addressing these two issues, the DP method has been outstanding among other conventional methods in preparing supported small metal nanoparticles [2]. However, the DP method has met great difficulties in preparing high-quality metal nanoparticles catalysts on many acidic supports (such as silica, WO x , zeolites) due to their relatively low point of zero charge (PZC) [3]. During the past decade, there has thus been an emergence of research efforts directed toward the use of pre-made uniform nanoparticles as precursors to prepare well-controlled metal nanocatalysts for investigating complicated interfacial catalytic mechanism [4][5][6]. In these colloidal methods, the influence of organic capping agents is often concerned.As compared to supported monometallic nanoparticles, the preparation of high-quality supported alloyed nanoparticles is even more challenging. Alloying has been well-documented as an effective strategy to tailor the catalytic performance of supported metal catalysts. On one hand, alloying provides an avenue to reduce the usage of expensive scare metal without compromising the overall catalytic activity. On the other hand, the electronic density and/or dispersion of catalytically active metal can be manipulated by the introduction of another metal species, thus tailoring the reaction pathway and often optimizing the overall catalytic properties. In order to obtain high-quality supported alloyed catalysts with uniform ultrasmall size and uniform composition, it is essential to have the metal precursors uniformly deposited onto the surface of supports before being converted into alloyed nanoparticles. Recently, Regalbuto and colleagues have developed a general and simple method to prepare ultrasmall alloyed metal nanoparticles based on both noble (i.e., Pt, Pd) and base metals (i.e., Ni, Co, Cu) [7]. The homogeneously alloyed metal nanoparticles have a narrow size...

show abstract

Reactive Deposition Versus Strong Electrostatic Adsorption (SEA): A Key to Highly Active Single Atom Co‐Catalysts in Photocatalytic H₂ Generation

et al. 2023

View full text Add to dashboard Cite

In recent years, the use of single atoms (SAs) has become of a rapidly increasing significance in photocatalytic H2 generation; here SA noble metals (mainly Pt SAs) can act as highly effective co‐catalysts. The classic strategy to decorate oxide semiconductor surfaces with maximally dispersed SAs relies on “strong electrostatic adsorption” (SEA) of suitable noble metal complexes. In the case of TiO2 – the classic benchmark photocatalyst – SEA calls for adsorption of cationic Pt complexes such as [(NH3)4Pt]2+ which then are thermally reacted to surface‐bound SAs. While SEA is widely used in literature, in the present work it is shown by a direct comparison that reactive attachment based on the reductive anchoring of SAs, e.g., from hexachloroplatinic(IV) acid (H2PtCl6) leads directly to SAs in a configuration with a significantly higher specific activity than SAs deposited with SEA – and this at a significantly lower Pt loading and without any thermal post‐deposition treatments. Overall, the work demonstrates that the reactive deposition strategy is superior to the classic SEA concept as it provides a direct electronically well‐connected SA‐anchoring and thus leads to highly active single‐atom sites in photocatalysis.

show abstract

Synthesis of very highly dispersed platinum catalysts supported on carbon xerogels by the strong electrostatic adsorption method

Cited by 132 publications

References 37 publications

Design of Pt/Carbon Xerogel Catalysts for PEM Fuel Cells

Design of Pt/Carbon Xerogel Catalysts for PEM Fuel Cells

Amine facilitates the synthesis of silica-supported ultrasmall bimetallic nanoparticles

Reactive Deposition Versus Strong Electrostatic Adsorption (SEA): A Key to Highly Active Single Atom Co‐Catalysts in Photocatalytic H₂ Generation

Contact Info

Product

Resources

About

Synthesis of very highly dispersed platinum catalysts supported on carbon xerogels by the strong electrostatic adsorption method

Cited by 132 publications

References 37 publications

Design of Pt/Carbon Xerogel Catalysts for PEM Fuel Cells

Design of Pt/Carbon Xerogel Catalysts for PEM Fuel Cells

Amine facilitates the synthesis of silica-supported ultrasmall bimetallic nanoparticles

Reactive Deposition Versus Strong Electrostatic Adsorption (SEA): A Key to Highly Active Single Atom Co‐Catalysts in Photocatalytic H2 Generation

Contact Info

Product

Resources

About

Reactive Deposition Versus Strong Electrostatic Adsorption (SEA): A Key to Highly Active Single Atom Co‐Catalysts in Photocatalytic H₂ Generation