Improving the catalytic activity of lanthanum manganese oxide with strontium doping for hydrogen peroxide reduction reaction in micro direct alcohol-hydrogen peroxide fuel cell

Abstract

The work presents lanthanum manganese oxide with strontium doping written as La1-xSrxMnO3±δ (LSMx; x = 0.0 and 0.6), using as an alternative catalyst for replacing high-cost platinum-based catalysts used for hydrogen peroxide reduction reaction (HPRR) applications in alkaline solution. Among LSMx series, the La0.4Sr0.6MnO3±δ (LSM0.6) is chosen due to its highest catalytic performance from our previous study. It is compared with LaMnO3±δ (LSM0.0) and thin-film platinum as a representative of the platinum-based catalyst and as a reference catalyst. With Sr-doping, the ratio of Mn4+ to Mn3+ of LSM0.6 increases and its catalytic activity improves. Both HPRR and oxygen reduction reaction (ORR) occur in micro direct alcohol-hydrogen peroxide fuel cell (μDAHPFC). As a cathode catalyst in μDAHPFC, although LSM0.6 gives higher performance compared to LSM0.0, it still exhibits lower performance compared to that of the thin-film platinum. The electrochemical impedance spectroscopy study also reveals that LSM0.6 exhibits higher conductivity compared to LSM0.0 but lower conductivity compared to that of the thin-film platinum. The main factors causing low open circuit voltage value could be the activation loss due to the charge transfer rate and mass transfer effect including the proton transfer across the casted proton electrolyte membrane and the fabrication of μDAHPFC.