Electro catalyst Composition with Redox Buffer Metal Oxides for Bi-functional Air Electrode

A method for preparing electrocatalyst composition comprising redox buffer metals, said method comprising steps of:

• (i) preparing cobalt-manganese hydroxides solution comprising of:
• a) preparing separate solutions of cobalt and manganese precursors in deionized water,
• b) mixing the precursor solutions of cobalt and manganese,
• c) adding alkaline base solution selected from the group consisting of an aqueous solution of NaOH, Na2CO3, NaHCO3, NH4OH, or combination thereof to the mixed precursor solution of cobalt and manganese obtained in step b), at a pH of 7 to 11 and obtaining precipitated cobalt-manganese hydroxides;
• (ii) preparing a redox buffer metal precursor solution comprising of:
• a) preparing separate solutions of cerium and Zirconyl precursors in deionized water,
• b) optionally mixing the cerium precursor solution and zirconyl precursor solution to obtain a composite solution;
• (iii) mixing of precipitated solution of cobalt-manganese hydroxides with redox buffer metal precursor solutions comprising of:
• a) mixing the precipitated solution of cobalt-manganese hydroxides obtained in step (i) c) with cerium precursor solution and zirconyl precursor solution obtained in step (ii) a) or a composite solution obtained in step (ii) b),
• b) stirred the resultant suspension for 12 hours,
• c) vacuum filtering the suspension obtained in step (iii) b) to obtain the catalyst slurry,
• d) repeatedly washing the catalyst precipitates obtained in step (iii) c) with deionized water, followed drying the obtained catalyst cake in oven at 50 to 100° C., and
• e) calcining the catalyst cake at 400-600° C. to obtain electro-catalyst composition with redox buffer metals of formula (1) (MnxOy)(Co)n+/CeiZrjO2, wherein x=1 to 5, y=2 to 8, n=2 to 3, i=0.01 to 0.75 and j=0.1 to 0.95.