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Surface Modification of Boron-Doped Diamond with Microcrystalline Copper Phthalocyanine: Oxygen Reduction Catalysis.

Gan P, Foord JS, Compton RG - ChemistryOpen (2015)

Bottom Line: Both unmodified and modified BDD electrodes of different surface terminations (namely hydrogen and oxygen) were compared via the electrochemical reduction of oxygen in aqueous solution.A significant lowering of the cathodic overpotential by about 500 mV was observed after modification of hydrogen-terminated (hydrophobic) diamond, while no voltammetric peak was seen on modified oxidised (hydrophilic) diamond, signifying greater interaction between copper phthalocyanine and the hydrogen-terminated BDD.Oxygen reduction was found to undergo a two-electron process on the modified hydrogen-terminated diamond, which was shown to be also active for the reduction of hydrogen peroxide.

View Article: PubMed Central - PubMed

Affiliation: Chemistry Research Laboratory, University of Oxford Mansfield Road, Oxford, OX1 3TA, United Kingdom.

ABSTRACT
Surface modification of boron-doped diamond (BDD) with copper phthalocyanine was achieved using a simple and convenient dropcast deposition, giving rise to a microcrystalline structure. Both unmodified and modified BDD electrodes of different surface terminations (namely hydrogen and oxygen) were compared via the electrochemical reduction of oxygen in aqueous solution. A significant lowering of the cathodic overpotential by about 500 mV was observed after modification of hydrogen-terminated (hydrophobic) diamond, while no voltammetric peak was seen on modified oxidised (hydrophilic) diamond, signifying greater interaction between copper phthalocyanine and the hydrogen-terminated BDD. Oxygen reduction was found to undergo a two-electron process on the modified hydrogen-terminated diamond, which was shown to be also active for the reduction of hydrogen peroxide. The lack of a further conversion of the peroxide was attributed to its rapid diffusion away from the triple phase boundary at which the reaction is expected to exclusively occur.

No MeSH data available.


Cyclic voltammograms for H-terminated BDD electrode in O2-saturated 0.1 m PBS pH 7 showing initial scan (solid line), second scan (dashed line), and subsequent scan after stirring (dotted line). Scan rate: 100 mV s−1.
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fig02: Cyclic voltammograms for H-terminated BDD electrode in O2-saturated 0.1 m PBS pH 7 showing initial scan (solid line), second scan (dashed line), and subsequent scan after stirring (dotted line). Scan rate: 100 mV s−1.

Mentions: Consecutive cyclic voltammetric scans were thus carried out, and the voltammograms are shown in Figure 2. The second scan showed a decrease in the peak current, which can be attributed to the slow removal of reaction products from the reaction sites. After the solution was stirred by bubbling with oxygen, the subsequent voltammogram showed a restoration of the peak current to that of the initial value. This confirms that the H-terminated diamond is indeed electrocatalytic compared to the O-terminated surface.


Surface Modification of Boron-Doped Diamond with Microcrystalline Copper Phthalocyanine: Oxygen Reduction Catalysis.

Gan P, Foord JS, Compton RG - ChemistryOpen (2015)

Cyclic voltammograms for H-terminated BDD electrode in O2-saturated 0.1 m PBS pH 7 showing initial scan (solid line), second scan (dashed line), and subsequent scan after stirring (dotted line). Scan rate: 100 mV s−1.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4608528&req=5

fig02: Cyclic voltammograms for H-terminated BDD electrode in O2-saturated 0.1 m PBS pH 7 showing initial scan (solid line), second scan (dashed line), and subsequent scan after stirring (dotted line). Scan rate: 100 mV s−1.
Mentions: Consecutive cyclic voltammetric scans were thus carried out, and the voltammograms are shown in Figure 2. The second scan showed a decrease in the peak current, which can be attributed to the slow removal of reaction products from the reaction sites. After the solution was stirred by bubbling with oxygen, the subsequent voltammogram showed a restoration of the peak current to that of the initial value. This confirms that the H-terminated diamond is indeed electrocatalytic compared to the O-terminated surface.

Bottom Line: Both unmodified and modified BDD electrodes of different surface terminations (namely hydrogen and oxygen) were compared via the electrochemical reduction of oxygen in aqueous solution.A significant lowering of the cathodic overpotential by about 500 mV was observed after modification of hydrogen-terminated (hydrophobic) diamond, while no voltammetric peak was seen on modified oxidised (hydrophilic) diamond, signifying greater interaction between copper phthalocyanine and the hydrogen-terminated BDD.Oxygen reduction was found to undergo a two-electron process on the modified hydrogen-terminated diamond, which was shown to be also active for the reduction of hydrogen peroxide.

View Article: PubMed Central - PubMed

Affiliation: Chemistry Research Laboratory, University of Oxford Mansfield Road, Oxford, OX1 3TA, United Kingdom.

ABSTRACT
Surface modification of boron-doped diamond (BDD) with copper phthalocyanine was achieved using a simple and convenient dropcast deposition, giving rise to a microcrystalline structure. Both unmodified and modified BDD electrodes of different surface terminations (namely hydrogen and oxygen) were compared via the electrochemical reduction of oxygen in aqueous solution. A significant lowering of the cathodic overpotential by about 500 mV was observed after modification of hydrogen-terminated (hydrophobic) diamond, while no voltammetric peak was seen on modified oxidised (hydrophilic) diamond, signifying greater interaction between copper phthalocyanine and the hydrogen-terminated BDD. Oxygen reduction was found to undergo a two-electron process on the modified hydrogen-terminated diamond, which was shown to be also active for the reduction of hydrogen peroxide. The lack of a further conversion of the peroxide was attributed to its rapid diffusion away from the triple phase boundary at which the reaction is expected to exclusively occur.

No MeSH data available.