Unusual electrochemical properties of low-doped boron-doped diamond electrodes containing sp2 carbon.

Unexpected phenomena displayed by low boron-doped diamond (BDD) electrodes are disclosed in the present work. Generally, the presence of sp2 non-diamond carbon impurities in BDD electrodes causes undesirable electrochemical properties, such as a reduced potential window and increased background current etc. However, we found that the poten-tial window and redox reaction in normally doped (1%) BDD and low doped (0.1%) BDD exhibited opposite tendencies depending on the extent of sp2 carbon. Moreover, we found that contrary to the usual expectations, low-doped BDD con-taining sp2 carbon hinders electron transfer, whereas in line with expectations, normally-doped BDD containing sp2 exhibits enhanced electron transfer. Surface analysis by X-ray/ultraviolet photoelectron spectroscopy (XPS/UPS) and electro-chemical methods are utilized to explain these unusual phenomena. This work indicates that, the electrochemical proper-ties of low-doped BDD containing sp2 might be due partially to the high level of surface oxygen, the large work function, the low carrier density and the existence of different types of sp2 carbon.