Modified Boron-Doped Diamond Electrodes for Sensors and Electroanalysis

Boron-doped diamond (BDD) has been established as a superior electrode among other conventional solid electrodes due to its unique properties, such as very low background current, wide potential window, and high physical and chemical stability. However, in compare to metal electrodes, BDD has much lower kinetic activity in some important chemical reactions, which causes limitation for sensor and biosensor applications. Modification of BDD surface with redox-active particles/compounds was reported to facilitate electron transfer between the BDD substrate and analytes with a significant reduction in activation overpotential; therefore, the catalytic activity and sensitivity are improved. In addition, the modification can increase the selectivity in some reactions. On the other hand, to have a stable modified surface of BDD electrode is not easy, since the main composition of BDD is carbon atoms with sp3 configuration, which is very compact and stable, and actually one of the advance characteristics of BDD electrodes. However, the stability of the BDD surface causes the modified surface to be easily detached or dissolved after several usages. In this chapter, preparations and applications of the modified BDD for electrochemical sensors and biosensors are described and compared.