Electrochemistry of nitrogen and boron Bi-element incorporated diamond films

Boron doped diamond (BDD) has been widely used in various electrochemical fields, due to its unique physical and chemical properties. However, the investigation of the electrochemistry of bi-element incorporated diamond, especially the variation of surface components after nitrogen incorporation into BDD and the corresponding electron transfer of inner-sphere and outer-sphere redox probes is still lacking. Here, the electrochemistry of nitrogen and boron bi-element incorporated diamond (NBD) is thus investigated in both inner and outer redox systems, namely in [Fe(CN)6]3-/4- and [Ru(NH3)6]3+/2+ solutions. On the NBD electrode, enhanced electrochemical responses are achieved for both outer- and inner-sphere redox reactions. Such enhancement originates from the enrichment of CO groups and the increased amount of sp2 species in the NBD film. Moreover, the nitrogen and boron atoms incorporated in diamond modulate the surface polarities and the electronic states of diamond. Based on the enhanced and stable capacitance of the NBD electrode, its electrochemical energy applications are explored by assembling its supercapacitor as a case study. This work reveals the influence of sp2 species and oxygen-contained function group on the electrochemistry of bi-element incorporated diamond films and reveals their potential electrochemical applications.