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Inhibition of CO poisoning on Pt catalyst coupled with the reduction of toxic hexavalent chromium in a dual-functional fuel cell.

Chung DY, Kim HI, Chung YH, Lee MJ, Yoo SJ, Bokare AD, Choi W, Sung YE - Sci Rep (2014)

Bottom Line: Carbon monoxide (CO), an intermediate of methanol oxidation that is primarily responsible for Pt catalyst deactivation, can be used as an in-situ reducing agent for hexavalent chromium (Cr (VI)) with reactivating the CO-poisoned Pt catalyst.Using electro-oxidation measurements, the oxidation of adsorbed CO molecules coupled with the concurrent conversion of Cr (VI) to Cr (III) was confirmed.This concept was also successfully applied to a methanol fuel cell to enhance its performance efficiency and to remove toxic Cr (VI) at the same time.

View Article: PubMed Central - PubMed

Affiliation: 1] Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 151-742, Republic of Korea [2] School of Chemical and Biological Engineering, Seoul National University, Seoul 151-742, Republic of Korea.

ABSTRACT
We propose a method to enhance the fuel cell efficiency with the simultaneous removal of toxic heavy metal ions. Carbon monoxide (CO), an intermediate of methanol oxidation that is primarily responsible for Pt catalyst deactivation, can be used as an in-situ reducing agent for hexavalent chromium (Cr (VI)) with reactivating the CO-poisoned Pt catalyst. Using electro-oxidation measurements, the oxidation of adsorbed CO molecules coupled with the concurrent conversion of Cr (VI) to Cr (III) was confirmed. This concept was also successfully applied to a methanol fuel cell to enhance its performance efficiency and to remove toxic Cr (VI) at the same time.

No MeSH data available.


Related in: MedlinePlus

Schematic diagrams of concepts (a) CO poisoning through indirect methanol oxidation, and (b) proposed cleaning process by introduction of toxic hexavalent chromium ions as “CO scavenger”.
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f2: Schematic diagrams of concepts (a) CO poisoning through indirect methanol oxidation, and (b) proposed cleaning process by introduction of toxic hexavalent chromium ions as “CO scavenger”.

Mentions: To test the reaction between CO and Cr (VI), electro-oxidation of CO was investigated in the absence and presence of Cr (VI) and their detail experimental conditions are given in Supporting Information and Figure S1a. Before the CO adsorption, pre-cycling was performed until a stable cyclic voltammogram was obtained under Ar purging. CO gas was then introduced at a set potential of 0.05 VRHE to adsorb CO on the Pt surface. After 5 min, the CO molecules were fully adsorbed on Pt and before CO oxidation, both catalysts for the absence and presence of Cr (VI) had the similar amount of CO adsorption, as shown in Figure S1b. Non-adsorbed CO molecules remaining in the electrolyte were removed by Ar purging for 20 min. After purging, the working electrode was immersed in a solution containing hexavalent chromium and perchloric acid. A control solution containing only perchloric acid was also tested as a reference. In the reference case (electrode immersed in perchloric acid only), the CO oxidation peaks were observed from 0.6 to 1.2 VRHE in the first cycle (Figure 1a, region II). However, in the presence of Cr (VI), the CO oxidation peaks were completely absent, which means that adsorbed CO was removed during the immersion of Cr (VI) solution. The desorption of hydrogen is also clearly visible. (Hupd (underpotential deposition of proton) represents the electro-deposition of proton at a less negative potential than the reduction potential of proton, region I). The overall reaction scheme is shown as Figure 2.


Inhibition of CO poisoning on Pt catalyst coupled with the reduction of toxic hexavalent chromium in a dual-functional fuel cell.

Chung DY, Kim HI, Chung YH, Lee MJ, Yoo SJ, Bokare AD, Choi W, Sung YE - Sci Rep (2014)

Schematic diagrams of concepts (a) CO poisoning through indirect methanol oxidation, and (b) proposed cleaning process by introduction of toxic hexavalent chromium ions as “CO scavenger”.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4264001&req=5

f2: Schematic diagrams of concepts (a) CO poisoning through indirect methanol oxidation, and (b) proposed cleaning process by introduction of toxic hexavalent chromium ions as “CO scavenger”.
Mentions: To test the reaction between CO and Cr (VI), electro-oxidation of CO was investigated in the absence and presence of Cr (VI) and their detail experimental conditions are given in Supporting Information and Figure S1a. Before the CO adsorption, pre-cycling was performed until a stable cyclic voltammogram was obtained under Ar purging. CO gas was then introduced at a set potential of 0.05 VRHE to adsorb CO on the Pt surface. After 5 min, the CO molecules were fully adsorbed on Pt and before CO oxidation, both catalysts for the absence and presence of Cr (VI) had the similar amount of CO adsorption, as shown in Figure S1b. Non-adsorbed CO molecules remaining in the electrolyte were removed by Ar purging for 20 min. After purging, the working electrode was immersed in a solution containing hexavalent chromium and perchloric acid. A control solution containing only perchloric acid was also tested as a reference. In the reference case (electrode immersed in perchloric acid only), the CO oxidation peaks were observed from 0.6 to 1.2 VRHE in the first cycle (Figure 1a, region II). However, in the presence of Cr (VI), the CO oxidation peaks were completely absent, which means that adsorbed CO was removed during the immersion of Cr (VI) solution. The desorption of hydrogen is also clearly visible. (Hupd (underpotential deposition of proton) represents the electro-deposition of proton at a less negative potential than the reduction potential of proton, region I). The overall reaction scheme is shown as Figure 2.

Bottom Line: Carbon monoxide (CO), an intermediate of methanol oxidation that is primarily responsible for Pt catalyst deactivation, can be used as an in-situ reducing agent for hexavalent chromium (Cr (VI)) with reactivating the CO-poisoned Pt catalyst.Using electro-oxidation measurements, the oxidation of adsorbed CO molecules coupled with the concurrent conversion of Cr (VI) to Cr (III) was confirmed.This concept was also successfully applied to a methanol fuel cell to enhance its performance efficiency and to remove toxic Cr (VI) at the same time.

View Article: PubMed Central - PubMed

Affiliation: 1] Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 151-742, Republic of Korea [2] School of Chemical and Biological Engineering, Seoul National University, Seoul 151-742, Republic of Korea.

ABSTRACT
We propose a method to enhance the fuel cell efficiency with the simultaneous removal of toxic heavy metal ions. Carbon monoxide (CO), an intermediate of methanol oxidation that is primarily responsible for Pt catalyst deactivation, can be used as an in-situ reducing agent for hexavalent chromium (Cr (VI)) with reactivating the CO-poisoned Pt catalyst. Using electro-oxidation measurements, the oxidation of adsorbed CO molecules coupled with the concurrent conversion of Cr (VI) to Cr (III) was confirmed. This concept was also successfully applied to a methanol fuel cell to enhance its performance efficiency and to remove toxic Cr (VI) at the same time.

No MeSH data available.


Related in: MedlinePlus