Synthesis of ternary electrocatalysts for exploration of methanol electro-oxidation in alkaline media

In the quest for alternate and efficient electrode materials, ternary metal electrocatalysts (TMEs), part of the perovskite family, were synthesized and tested for methanol electro-oxidation in alkaline media. La0.5Ca0.5MO3 (M = Ni, Co, or Mn) was synthesized via sol-gel method. X-ray diffraction analysis revealed that the perovskite crystal structure possesses characteristic sharp and crystalline peaks for all synthesized ternary electrocatalysts. The average particle size calculated using Debye–Scherrer equation was in the order of La0.5Ca0.5NiO3 (LCNO) > La0.5Ca0.5CoO3 (LCCO)> La0.5Ca0.5MnO3 (LCMO). The elemental composition of as prepared sample, LCCO was investigated via x-ray fluorescence spectroscopy. The qualitative and quantitative analysis revealed the presence of La, Ca and Co in parent crystal structure with percentage compositions of 9.0, 3.12 and 87.82% respectively. The particle size distribution was homogenous, as determined by scanning electron and transmission electron microscopes. The electrocatalytic activity of the synthesized ternary electrocatalysts was studied electrochemically by cyclic voltammetry. The calculated diffusion coefficient values showed that electrode surface of LCNO and LCCO have limited efficiency for diffusion related phenomenon. The heterogeneous rate constants inferred better electrode kinetics of LCCO and LCNO which exhibited good electrocatalytic behavior; sharp anodic peaks were observed in the potential range of +0.3 to 0.6 V and +0.6 to 0.8 V, respectively. Methanol electro-oxidation was found minimal in case of LCMO sample. We have observed that Co substitution at B-site of perovskite electrode materials attains better electrochemical properties, thus in relation with reported literature.