Electrochemical measurements
The electrochemical characteristics of the as-obtained products
were studied on a CHI660 electrochemical workstation (Chenhua, Shanghai) using cyclic voltammetry, chronopotentiometry
and electrochemical impedance testing by conguring the
samples into a three-electrode cell. The samples were used as
the working electrode, Pt foil was used as the counter electrode
and a saturated calomel electrode was used as the reference
electrode. The electrodes were prepared using high-purity
battery-grade Ni foil (0.18 mm thick) as the current collector.
The Ni foil was rst cleaned successively with detergent and
deionized water. A mixture containing 80 wt% MnO2 sample,
15 wt% acetylene black and 5 wt% polytetrauoroethylene was
well mixed and dried under vacuum at 120 C for 5 h. The electrode area was 1 cm2 and the loading density was about 2.0 mg
cm2
. The electrolyte was an aqueous solution of 1.0 mol L1 KOH.