Heterogeneous distribution of surface electrochemical activity in polycrystalline highly boron-doped diamond electrodes under deep anodic polarization

•Tendency for surface oxidation varies between individual BDD crystallites.•Anodic polarization conditions affect selectively grain properties.•(110)-Oriented planes are the most prone toward electrochemical oxidation.•Nanoscale impedance microscopy allows local electrode heterogeneity determination.

The surface homogeneity of boron-doped diamond electrodes is variable and depends on anodic polarization conditions. The differentiation factor is the gradual and localized change in surface termination. A series of measurements under different polarization conditions was performed in order to investigate the scale of this effect. Nanoscale impedance microscopy (NIM) revealed large variation of surface resistance in individual grains. Based on the obtained results, we claim that the level of electrochemical heterogeneity significantly depends on the crystallographic texture of BDD. Modification of boron-doped diamond surface termination under anodic oxidation is assumed to be a multistage process.

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