Binary (Ti/RuO2-TiO2) and ternary (Ti/RuO2-TiO2-IrO2) mixed metal oxides as promising catalysts for alkaline electrochemical oxidation of methanol.

[Display omitted] • Binary RuO 2 -TiO 2 and ternary RuO 2 -TiO 2 -IrO 2 MMO are coated on Ti by a simple approach. • All prepared Ti/MMO anodes exhibit significant activity toward the MOR in aq. KOH. • Ti/70%RuO 2 -30%TiO 2 and Ti/70%RuO 2 -25%TiO 2 -5%IrO 2 reveal the best performance for MOR. • Ternary catalyst has higher C dl , Γ* , D values, and lower onset potential than the binary. • MOR is zero and first-order for fuel and KOH at both catalysts, with high stability. In this study, binary and ternary mixed metal oxide (MMO) electrodes were fabricated and examined as promising electrocatalysts for direct methanol oxidation reaction (MOR). The binary (RuO 2 -TiO 2) and ternary (RuO 2 -TiO 2 -IrO 2) MMOs with various molar ratios were coated on Ti substrate via an eco-friendly simple co-deposition method. The optimal compositions were assessed by cyclic voltammetry (CV) as Ti/70 %RuO 2 -30 %TiO 2 and Ti/70 %RuO 2 -25 %TiO 2 -5 %IrO 2. Multiple physicochemical techniques were utilized to characterize these two catalysts. At 50 mV/s scan rate, the binary catalyst showed favorable activity for the MOR with a minimal onset potential of 0.20 V and a maximum current density of 35.46 mA/cm2 in 4 M KOH + 1 M CH 3 OH. However, the ternary catalyst surpassed the binary, displaying an onset potential of 0.10 V and a maximum current density of 67.69 mA/cm2 in 4 M KOH + 2 M CH 3 OH. In the meantime, the two electrocatalysts exhibited remarkable stability in long-term 20 h chronoamperometric (CA) electrolysis at their optimal conditions. Various physical traits were further estimated for the two proposed anodes to compare their relative capabilities. The results for the binary and ternary catalysts were, respectively, the double-layer capacitance (C dl) 54.30 and 63.43 mF/cm2, the surface excess (Γ*) 1.55 × 10-8 and 1.92 × 10-8 mol/cm2, and the diffusion coefficient (D) 1.09 × 10-8 and 5.43 × 10-8 cm2/s. This hints at the vital role of adding IrO 2 in the MMO binary catalyst to ameliorate its activity toward the MOR process in an alkaline environment. [ABSTRACT FROM AUTHOR]