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Platinum-modified covalent triazine frameworks hybridized with carbon nanoparticles as methanol-tolerant oxygen reduction electrocatalysts.

Kamiya K, Kamai R, Hashimoto K, Nakanishi S - Nat Commun (2014)

Bottom Line: Covalent triazine frameworks, which are crosslinked porous polymers with two-dimensional molecular structures, are promising materials for heterogeneous catalysts.Here we report that platinum-modified covalent triazine frameworks hybridized with conductive carbon nanoparticles are successfully synthesized by introducing carbon nanoparticles during the polymerization process of covalent triazine frameworks.The resulting materials exhibit clear electrocatalytic activity for oxygen reduction reactions in acidic solutions.

View Article: PubMed Central - PubMed

Affiliation: Department of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.

ABSTRACT
Covalent triazine frameworks, which are crosslinked porous polymers with two-dimensional molecular structures, are promising materials for heterogeneous catalysts. However, the application of the frameworks as electrocatalysts has not been achieved to date because of their poor electrical conductivity. Here we report that platinum-modified covalent triazine frameworks hybridized with conductive carbon nanoparticles are successfully synthesized by introducing carbon nanoparticles during the polymerization process of covalent triazine frameworks. The resulting materials exhibit clear electrocatalytic activity for oxygen reduction reactions in acidic solutions. More interestingly, the platinum-modified covalent triazine frameworks show almost no activity for methanol oxidation, in contrast to commercial carbon-supported platinum. Thus, platinum-modified covalent triazine frameworks hybridized with carbon nanoparticles exhibit selective activity for oxygen reduction reactions even in the presence of high concentrations of methanol, which indicates potential utility as a cathode catalyst in direct methanol fuel cells.

No MeSH data available.


Related in: MedlinePlus

ORR activities of Pt-CTF/CP and Pt/C in the presence of methanol.j versus U curves for (a) Pt-CTF/CP and (b) 20 wt% Pt/C in 0.5 M H2SO4 saturated with dissolved oxygen. Methanol concentration: (black) 0 M, (blue) 0.1 M and (red) 1.0 M.
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f3: ORR activities of Pt-CTF/CP and Pt/C in the presence of methanol.j versus U curves for (a) Pt-CTF/CP and (b) 20 wt% Pt/C in 0.5 M H2SO4 saturated with dissolved oxygen. Methanol concentration: (black) 0 M, (blue) 0.1 M and (red) 1.0 M.

Mentions: Next, to investigate the methanol tolerance of Pt-CTF/CP, we intentionally added methanol to a 0.5-M H2SO4 solution in the presence of oxygen. Cyclic voltammograms obtained in the presence of methanol are shown in Fig. 3. In case of a commercial 20 wt% Pt/C, the oxidation peak of methanol can be clearly observed at around +600 mV versus RHE (Fig. 3b). After the addition of 1 M methanol, the onset potential of the cathodic current shifted ~200 mV in the negative direction, reaching 580 mV versus RHE. In contrast, surprisingly, the overlap of the methanol oxidation current with that of the ORR was almost negligible for Pt-CTF/CP even in the presence of 1 M methanol. To directly compare the methanol oxidation activity of Pt-CTF/CP and 20 wt% Pt/C, we obtained cyclic voltammograms in H2SO4 solution containing methanol in the absence of dissolved oxygen (Fig. 4). The peak currents for methanol oxidation with Pt-CTF/CP (Fig. 4a) were ~1/40 compared with those with Pt/C (Fig. 4b). We confirmed that methanol oxidation is inactive even in 0.5 M HClO4 as shown in Supplementary Fig. 3, which excludes the possibility that the methanol tolerance originated from the suppression of methanol oxidation by strongly adsorbed sulfate/bisulfate3132. Thus, the above results clearly showed that Pt-CTF/CP exhibits little activity with regard to methanol oxidation.


Platinum-modified covalent triazine frameworks hybridized with carbon nanoparticles as methanol-tolerant oxygen reduction electrocatalysts.

Kamiya K, Kamai R, Hashimoto K, Nakanishi S - Nat Commun (2014)

ORR activities of Pt-CTF/CP and Pt/C in the presence of methanol.j versus U curves for (a) Pt-CTF/CP and (b) 20 wt% Pt/C in 0.5 M H2SO4 saturated with dissolved oxygen. Methanol concentration: (black) 0 M, (blue) 0.1 M and (red) 1.0 M.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4199112&req=5

f3: ORR activities of Pt-CTF/CP and Pt/C in the presence of methanol.j versus U curves for (a) Pt-CTF/CP and (b) 20 wt% Pt/C in 0.5 M H2SO4 saturated with dissolved oxygen. Methanol concentration: (black) 0 M, (blue) 0.1 M and (red) 1.0 M.
Mentions: Next, to investigate the methanol tolerance of Pt-CTF/CP, we intentionally added methanol to a 0.5-M H2SO4 solution in the presence of oxygen. Cyclic voltammograms obtained in the presence of methanol are shown in Fig. 3. In case of a commercial 20 wt% Pt/C, the oxidation peak of methanol can be clearly observed at around +600 mV versus RHE (Fig. 3b). After the addition of 1 M methanol, the onset potential of the cathodic current shifted ~200 mV in the negative direction, reaching 580 mV versus RHE. In contrast, surprisingly, the overlap of the methanol oxidation current with that of the ORR was almost negligible for Pt-CTF/CP even in the presence of 1 M methanol. To directly compare the methanol oxidation activity of Pt-CTF/CP and 20 wt% Pt/C, we obtained cyclic voltammograms in H2SO4 solution containing methanol in the absence of dissolved oxygen (Fig. 4). The peak currents for methanol oxidation with Pt-CTF/CP (Fig. 4a) were ~1/40 compared with those with Pt/C (Fig. 4b). We confirmed that methanol oxidation is inactive even in 0.5 M HClO4 as shown in Supplementary Fig. 3, which excludes the possibility that the methanol tolerance originated from the suppression of methanol oxidation by strongly adsorbed sulfate/bisulfate3132. Thus, the above results clearly showed that Pt-CTF/CP exhibits little activity with regard to methanol oxidation.

Bottom Line: Covalent triazine frameworks, which are crosslinked porous polymers with two-dimensional molecular structures, are promising materials for heterogeneous catalysts.Here we report that platinum-modified covalent triazine frameworks hybridized with conductive carbon nanoparticles are successfully synthesized by introducing carbon nanoparticles during the polymerization process of covalent triazine frameworks.The resulting materials exhibit clear electrocatalytic activity for oxygen reduction reactions in acidic solutions.

View Article: PubMed Central - PubMed

Affiliation: Department of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.

ABSTRACT
Covalent triazine frameworks, which are crosslinked porous polymers with two-dimensional molecular structures, are promising materials for heterogeneous catalysts. However, the application of the frameworks as electrocatalysts has not been achieved to date because of their poor electrical conductivity. Here we report that platinum-modified covalent triazine frameworks hybridized with conductive carbon nanoparticles are successfully synthesized by introducing carbon nanoparticles during the polymerization process of covalent triazine frameworks. The resulting materials exhibit clear electrocatalytic activity for oxygen reduction reactions in acidic solutions. More interestingly, the platinum-modified covalent triazine frameworks show almost no activity for methanol oxidation, in contrast to commercial carbon-supported platinum. Thus, platinum-modified covalent triazine frameworks hybridized with carbon nanoparticles exhibit selective activity for oxygen reduction reactions even in the presence of high concentrations of methanol, which indicates potential utility as a cathode catalyst in direct methanol fuel cells.

No MeSH data available.


Related in: MedlinePlus