Figure 5. CV of vanadium (IV) on gold (Au-BT). The small cathodic current peak indicates that the oxidation V(IV) → V(V) is irreversible. Note that the cathodic peak at 0.5 V results from the sulphuric acid

From

Vanadium Redox Flow Batteries with Different Electrodes and Membranes

A. Habekost

World Journal of Chemical Education. 2018, 6(1), 8-13 doi:10.12691/wjce-6-1-2