Determination of surface area of carbon-black by simple cyclic-voltammetry measurements in aqueous H2SO4

Determination of the surface area of commercial carbon-black (CB) by cyclic-voltammetry (CV) measurements of the electrochemical double-layer charge (Q) in aqueous sulfuric acid was investigated. Various factors that affect the Q value associated with CB, including: the presence of redox-reversible function-groups, the binders used for the formation of thin-film CB electrodes, the scan rates of the CV measurement, H2SO4 electrolyte concentration and the volume of air contained in the pores of the CB samples were examined. Conditions for measuring Q without interference from these factors were investigated and the data derived, without interference, was found to correlate well with the surface area of the CB. The results show that the total Brunauer–Emmett–Teller (BET) surface area shows good correlation (R2 = 0.993) with the Q value corresponding to a full charge/discharge of the CB (Q0), obtained by extrapolation at a zero scan rate; additionally, the CB micropore surface area (diameter < 2 nm) shows good linear correlation with the Q deficiency (Q0–Q), measured at 5 mV s−1 (R2 = 0.998).