Characterization of multi-walled carbon nanotubes catalyst supports by point of zero charge

Lee, Sungchul; Zhang, Zhiteng; Wang, Xiaoming; Pfefferle, Lisa D.; Haller, Gary L.

doi:10.1016/j.cattod.2010.10.031

Cited by 43 publications

(36 citation statements)

References 12 publications

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“…Two precursors, zirconium oxyphthalocyanine (ZrOPc) and zirconium acetylacetonate [Zr(acac) 4 ], were chosen based on previous studies [19,23] especially for their difference in atomic constitutions and solubility in organic solvents. ZrOPc contains less molecular oxygen but is nitrogen-rich, while, Zr(acac) 4 is an oxygen-rich but nitrogen-free precursor.…”

Section: Introductionmentioning

confidence: 99%

Synthesis optimization of carbon-supported ZrO2 nanoparticles from different organometallic precursors

et al. 2017

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We report here the synthesis of carbon-supported ZrO 2 nanoparticles from zirconium oxyphthalocyanine (ZrOPc) and acetylacetonate [Zr(acac) 4 ]. Using thermogravimetric analysis (TGA) coupled with mass spectrometry (MS), we could investigate the thermal decomposition behavior of the chosen precursors. According to those results, we chose the heat treatment temperatures (T HT ) using partial oxidizing (PO) and reducing (RED) atmosphere. By X-ray diffraction we detected structure and size of the nanoparticles; the size was further confirmed by transmission electron microscopy. ZrO 2 formation happens at lower temperature with Zr(acac) 4 than with ZrOPc, due to the lower thermal stability and a higher oxygen amount in Zr(acac) 4 . Using ZrOPc at T HT C900°C, PO conditions facilitate the crystallite growth and formation of distinct tetragonal ZrO 2 , while with Zr(acac) 4 a distinct tetragonal ZrO 2 phase is observed already at T HT C750°C in both RED and PO conditions. Tuning of ZrO 2 nanocrystallite size from 5 to 9 nm by varying the precursor loading is also demonstrated. The chemical state of zirconium was analyzed by X-ray photoelectron spectroscopy, which confirms ZrO 2 formation from different synthesis routes.

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Section: Introductionmentioning

confidence: 99%

Synthesis optimization of carbon-supported ZrO2 nanoparticles from different organometallic precursors

et al. 2017

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“…While using MWNTs as catalyst supports, the point-of-zero charge [PZC, defined as the pH at which the solid-aqueous solution interface is electrostatically neutral, according to the electrical double layer model described by Gouy-Chapman theory (Brown et al, 1999)] is an important parameter to consider when anchoring metal complex precursors to maximize dispersion and loading on the MWNT sidewalls. Lee et al (2011) showed that the treatment of nitric acid-oxidized MWNTs by ethanol reduction at 20 atm and 180°C was an efficient method for producing a high surface density of −OH groups, which in turn provided effective tethering points for grafting metal acetylacetone metal complexes to the MWNT surface. Since the tethering of cationic/anionic precursors is Coulombic in nature, the PZC can serve as a guide for electrostatic attachment of precursors to engineer the MWNT sidewalls.…”

Section: Physical and Chemical Properties Of Carbon Nanotubesmentioning

confidence: 99%

Aqueous Solution Surface Chemistry of Carbon Nanotubes

Deb¹,

Chusuei²

2013

Physical and Chemical Properties of Carbon Nanotubes

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“…Carbon materials in the form of nanofibers and nanotubes have great potential as catalyst supports owing to their high specific surface area, mechanical strength, and flexibility [1][2][3] and have been increasingly used as such [4]. A survey of Pt nanoparticle synthesis on these newer forms of carbon over the last three years turns up the two dozen papers listed in Table 1.…”

Section: Introductionmentioning

confidence: 99%

Electrostatic Adsorption of Platinum onto Carbon Nanotubes and Nanofibers for Nanoparticle Synthesis

Banerjee

Contreras-Mora

McQuiston

et al. 2018

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Strong Electrostatic Adsorption (SEA) has been demonstrated as a simple, scientific method to prepare well dispersed Pt nanoparticles over typical forms of carbon: activated, black, and graphitic carbons. Many varieties of specialty carbons have been invented in the last few decades including multi-walled nanotubes, nanofibers, graphene nanoplatelets, etc. In this work, we explore whether SEA can be applied to these specialty carbons for the synthesis of Pt nanoparticles. Over a number of oxidized and unoxidized multiwalled nanotubes and nanofibers, the point of zero charge (PZC) was measured and the uptake of anionic Pt complexes (Pt hexachloride, [PtCl 6 ] 2− , and cationic Pt complexes (platinum tetraammine, [Pt(NH 3 ) 4 ] 2+ ) as functions of final pH were surveyed. Pt nanoparticles on the various supports were synthesized at the optimal pH and were characterized by x-ray diffraction (XRD) and scanning transmission electron microscopy (STEM). The specialty carbons displayed volcano-shaped uptake curves typical of electrostatic adsorption for both Pt anions at low pH and Pt cations at high pH. However, the regimes of uptake often did not correspond to the measured PZC, probably due to surface impurities from the carbon manufacturing process. This renders the measured PZC of these specialty carbons unreliable for predicting anion and cation uptake. On the other hand, the anion and cation uptake curves provide an "effective" PZC and do indicate the optimal pH for the synthesis of ultrasmall nanoparticle synthesis. High resolution STEM imaging also showed that with SEA it is possible to disperse nanoparticles on the surface as well as the inner walls of the specialty carbons.

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Characterization of multi-walled carbon nanotubes catalyst supports by point of zero charge

Cited by 43 publications

References 12 publications

Synthesis optimization of carbon-supported ZrO2 nanoparticles from different organometallic precursors

Synthesis optimization of carbon-supported ZrO2 nanoparticles from different organometallic precursors

Aqueous Solution Surface Chemistry of Carbon Nanotubes

Electrostatic Adsorption of Platinum onto Carbon Nanotubes and Nanofibers for Nanoparticle Synthesis

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