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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 (H-BDD, solid line) and O-terminated (O-BDD, dashed line) BDD electrodes in N2-saturated (above) and O2-saturated (below) 0.1 m PBS pH 7. Scan rate: 100 mV s−1. The potential was swept in a negative direction from 0 V.
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fig01: Cyclic voltammograms for H-terminated (H-BDD, solid line) and O-terminated (O-BDD, dashed line) BDD electrodes in N2-saturated (above) and O2-saturated (below) 0.1 m PBS pH 7. Scan rate: 100 mV s−1. The potential was swept in a negative direction from 0 V.

Mentions: Cyclic voltammetry was first carried out on the unmodified boron-doped diamond with surface terminations of hydrogen and oxygen, in both O2- and N2-saturated phosphate buffer solution (PBS) at pH 7, to provide a basis for understanding the oxygen reduction at these electrodes. The cyclic voltammograms obtained are shown in Figure 1. In the N2-saturated solution, both the hydrogen- and oxygen-terminated diamond gave very little response. However, in the O2-saturated solution, the two types of surfaces gave rise to a different response. At the O-terminated surface there was no apparent peak, whereas at the H-terminated surface, a large and irreversible voltammetric peak was observed with a peak potential at −1.09 V (vs. Ag/AgCl), which can be attributed to the irreversible reduction of oxygen to hydrogen peroxide,19 as given by Equation 2. The two-electron reduction of oxygen on the H-terminated diamond is typical of the peroxide pathway commonly seen on carbon electrodes.18b,20


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 (H-BDD, solid line) and O-terminated (O-BDD, dashed line) BDD electrodes in N2-saturated (above) and O2-saturated (below) 0.1 m PBS pH 7. Scan rate: 100 mV s−1. The potential was swept in a negative direction from 0 V.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig01: Cyclic voltammograms for H-terminated (H-BDD, solid line) and O-terminated (O-BDD, dashed line) BDD electrodes in N2-saturated (above) and O2-saturated (below) 0.1 m PBS pH 7. Scan rate: 100 mV s−1. The potential was swept in a negative direction from 0 V.
Mentions: Cyclic voltammetry was first carried out on the unmodified boron-doped diamond with surface terminations of hydrogen and oxygen, in both O2- and N2-saturated phosphate buffer solution (PBS) at pH 7, to provide a basis for understanding the oxygen reduction at these electrodes. The cyclic voltammograms obtained are shown in Figure 1. In the N2-saturated solution, both the hydrogen- and oxygen-terminated diamond gave very little response. However, in the O2-saturated solution, the two types of surfaces gave rise to a different response. At the O-terminated surface there was no apparent peak, whereas at the H-terminated surface, a large and irreversible voltammetric peak was observed with a peak potential at −1.09 V (vs. Ag/AgCl), which can be attributed to the irreversible reduction of oxygen to hydrogen peroxide,19 as given by Equation 2. The two-electron reduction of oxygen on the H-terminated diamond is typical of the peroxide pathway commonly seen on carbon electrodes.18b,20

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.