Surface Hydrogenation of Boron-Doped Diamond Electrodes by Cathodic Reduction

Abstract

Boron-doped diamond (BDD) has attracted much attention as a promising electrode material especially for electrochemical sensing systems, because it has excellent properties such as a wide potential window and low background current. It is known that the electrochemical properties of BDD electrodes are very sensitive to the surface termination such as to whether it is hydrogen- or oxygen-terminated. Pretreating BDD electrodes by cathodic reduction (CR) to hydrogenate the surface has been widely used to achieve high sensitivity. However, little is known about the effects of the CR treatment conditions on surface hydrogenation. In this Article, we report on a systematic study of CR treatments that can achieve effective surface hydrogenation. As a result, we found that the surface hydrogenation could be improved by applying a more negative potential in a lower pH solution. This is because hydrogen atoms generated from protons in the CR treatment contribute to the surface hydrogenation. After CR treatments, BDD surface could be hydrogenated not completely but sufficiently to achieve high sensitivity for electrochemical sensing. In addition, we confirmed that hydrogenation with high repeatability could be achieved.

Analytical Applications of Electrochemically Pretreated Boron‐Doped Diamond Electrodes

“…In 2010, Salazar‐Banda et al ., based on the CV and EIS responses of the [Fe(CN) 6 ] 3−/4− redox pair, recommended the following galvanostatic CPT in a 0.5 mol L −1 H 2 SO 4 aqueous solution: −1 A cm −2 for 9 s, i. e . a q pt value of −9 C cm −2 ; interestingly, a similar value of q pt (−9.25 C cm −2 ) was indicated by Kasahara et al . as being the most effective condition for the activation of a BDDE in a 0.1 mol L −1 H 2 SO 4 aqueous solution by applying −5 V vs .…”

“…showed that BDD surfaces do not need to be highly hydrogenated to ensure that a reversible voltammetric behavior is obtained for the [Fe(CN) 6 ] 3−/4− redox system. Immediately after, Kasahara et al . reported that, for a fixed value of the pretreatment electric charge, q pt (−9.25 C cm −2 ), the attained degree of hydrogenation of the BDDE surface was higher when the CPT was performed using an acidic solution (pH=0.9).…”

“…Less intense current density values were used in the significantly shorter pulses: ±10 mA cm −2 (50 pulses of 100 ms duration; thus, a total activation time of 10 s and q pt =±50 mC cm −2 ). Despite the low value of | q pt |, the use of this activation protocol on an aged BDDE led to the recovery of its electrochemical activity for the [Fe(CN) 6 ] 3−/4− redox pair, as determined by CV and electrochemical impedance spectroscopy – EIS (▵ E p =60 mV and k 0 =6.1×10 −2 cm s −1 , respectively); in contrast to what was reported by Kasahara et al ., the more alkaline the LiClO 4 solution, better the activation of the BDDE. However, to reactivate a BDDE that became fouled after CV cycles were performed in human urine, the activation time had to be tripled.…”

Multifrequency nanoscale impedance microscopy (m-NIM): A novel approach towards detection of selective and subtle modifications on the surface of polycrystalline boron-doped diamond electrodes

“…The different surface terminations of BDDs show various electrochemical responses towards redox species. This enables the selective detection of specific target compounds [54]. Ivandini et al [55] reported that oxalic acid could be determined only at hydrogen-terminated BDD surface.…”

Increasing the Electric Double‐Layer Capacitance in Boron‐Doped Diamond Electrodes

“…The electrical conductivity of BDD can be controlled from semiconducting to superconducting by adjusting the boron concentration, and this has can be used to influence the electrochemical properties. In addition, the electrochemical properties of BDD are also affected by several factors including the amount of sp 2 carbon impurity, the crystal orientation,, and the surface termination . Therefore, we can design BDD electrodes appropriate for a diverse range of applications …”