Perovskite-type La2−xSrxNiO4 (0 ≤ x ≤ 1) as active anode materials for methanol oxidation in alkaline solutions

Abstract

Perovskite-type ternary oxides with molecular formulae, La2−xSrxNiO4 (0 ≤ x ≤ 1), were prepared by a modified citric acid sol–gel route at 600 °C for their possible use in a direct methanol fuel cell (DMFC). The study was conducted by cyclic voltammetry, chronoamperometry, impedance and anodic Tafel polarization techniques. The results showed that the electrocatalytic activity of the base oxide (x = 0) in 1 M KOH plus 1 M CH3OH at 25 °C increases with x, the observed current densities being 23.6, 47.3, 43.2 and 50.9 mA cm−2 at a scan rate of 10 mV s−1 and E = 0.6 V versus Hg/HgO for oxides with x = 0, 0.25, 0.5 and 1.0, respectively. All the four perovskite anodes used in this study did not indicate any poisoning by the methanol oxidation intermediates/products. The methanol electro-oxidation reaction followed a Tafel slope of 2 × 2.303RT/3F (=40 mV decade−1) on each oxide catalyst, regardless of Sr content.