Mn-W oxide anodes prepared by thermal decomposition for oxygen evolution in seawater electrolysis

Manganese-tungsten oxide electrodes have high efficiency for oxygen evolution in seawater electrolysis. Manganese oxide, tungsten oxide and manganese-tungsten oxides were coated on the IrO2-coated titanium (IrO2/Ti electrode) by thermal decomposition. The oxygen evolution efficiencies at 200 A.m(-2) of the manganese oxide and tungsten oxide electrodes in 0.5 M NaCl solution at pH 8 and 30 degrees C were 70 and 68%, respectively. The efficiency for oxygen evolution is enhanced by small amounts of mutual additions into manganese oxide or tungsten oxide. In particular, the efficiencies of alpha-Mn2O3-type oxide with 15 mol% W6+ and WO3-type oxide with 10 mol% Mn2+ go up to over 92 and 86%, respectively Further increase in additives leads to the formation of MnWO4 and to a significant decrease in the oxygen evolution efficiency.