Pt–Ru/Al2O3–C nanocomposites as direct methanol fuel cell catalysts for electrooxidation of methanol in acidic medium

Abstract

The development of potential low cost anode catalyst–supporting matrix combinations for application in direct methanol fuel cells (DMFCs) has been an effective area of research till date, primarily due to the slower kinetics of the methanol oxidation reaction and poisoning of the catalyst by carbonaceous species. In this work, we have employed different ratios of Al₂O₃ and Vulcan carbon (i.e. Al₂O₃ : Vulcan carbon (w/w) = 3 : 1, 2 : 1, 1 : 1) as supporting matrices for a Pt–Ru catalyst. Pt and Ru nanoparticles were deposited from a fixed amount of precursor salts H₂PtCl₆ and RuCl₃, respectively, by employing a NaBH₄ reduction method at 80 °C. Pt–Ru/Al₂O₃–Vulcan carbon exhibited the highest catalytic activity when the weight ratio of Al₂O₃ to Vulcan carbon was maintained at 2 : 1. This combination generated a peak current density of 399.6 μA cm⁻². Furthermore, the Pt–Ru/Al₂O₃–Vulcan carbon (2 : 1) catalyst system produced a current density of 148.92 mA cm⁻² at +0.2 V and a maximum power density of 29.78 mW cm⁻², using non-humidified air as the catholyte at 60 °C. However, when humidified air was used as the catholyte, a current density of 220.1 mA cm⁻² at +0.2 V and a maximum power density of 44.02 mW cm⁻² were obtained for the Pt–Ru/Al₂O₃–C (2 : 1) anode catalyst.