Sol–gel synthesis of Pt-Ru-Os-Ir based anode electro-catalysts for direct methanol fuel cells

A high specific surface area (∼95 m2/g) Pt44Ru41Os10Ir5 based anode electro-catalysts for direct methanol fuel cell, synthesized by a novel complexed sol–gel (CSG) process, shows better catalytic activity in comparison to pure equi-atomic compositions of Pt-50 at.% Ru anode catalysts synthesized by similar sol–gel processes. A homogeneous amorphous gel was successfully synthesized by complexing platinum(II) acetylacetonate, ruthenium(III) acetylacetonate, iridium(III) acetylacetonate and osmium(III) chloride with tetramethylammonium hydroxide (TMAH) used as a complexing agent. Phase-pure Pt(Ru,Os,Ir) and Pt(Ru) solid solutions possessing high specific surface area (SSA) (∼90–120 m2/g) were successfully synthesized by thermal decomposition of the amorphous gel followed by controlled removal of carbonaceous species present in the thermally treated powders. The controlled removal of carbon, present in the thermally treated Pt-Ru-Os-Ir powder, has been successfully achieved by conducting precise thermal treatments of the thermally treated powders using controlled oxidizing atmospheres. Results indicate that the nano-crystalline pure Pt(Ru,Os,Ir) solid solution of nominal composition Pt-41 at.%Ru-10 at.%Os-5 at.% Ir possessing good chemical homogeneity exhibit excellent catalytic activity, demonstrating the potential of the novel complexed sol–gel process for synthesizing high-performance Pt-Ru-Os-Ir based catalysts for direct methanol fuel cells.

Research highlights▶ Complex sol–gel synthesis (CSG) of high specific surface area Pt-Ru-Os-Ir catalysts. ▶ Catalysts exhibit specific surface area of ∼95 m2/g. ▶ Electrocatalytic activity is 35–40% higher than CSG derived Pt0.5Ru0.5 and commercially obtained JM catalyst.