which is comparable to that of the B-doped diamond electrode but much wider
than the exfoliated graphite electrode (∼2.2 V) [34]. The anodic
peak locating at 1.5 V may be due to the oxidation of non-diamond
carbon impurities at the surface and the broad cathodic peak at
−0.5 V is caused by the reduction of the by-product during anodic
oxidation [35]. The potential window range of 8% sample in our
work (∼3.1 V) is wider than that hybrid diamond/graphite structure
fabricated with the presence of N2 (∼1.3 V) [17]. The reason may