Enhanced Catalytic Performance of Strontium-Doped Lanthanum Manganites by the Presence of Molybdenum Oxides for Electro-Reduction of Hydrogen Peroxide

Ludmila Xavier,Renata Diniz,Thérèse Ebambi,Vanessa Lins,Luciano Montoro,Tulio Matencio

doi:10.21577/0103-5053.20220016

Abstract

In this work, two catalysts, lanthanum manganite strontium-doped perovskite without (LSM) and with (LSMMO) mixed molybdenum oxides, were synthesized by the sol-gel route and deposited by immersion in carbon cloth substrates. Their performance as cathodes in the hydrogen peroxide reduction reaction (HPRR) and oxygen reduction reaction (ORR) was investigated through cyclic voltammetry and electrochemical impedance spectroscopy, the electrocatalytic efficiency of these electrodes in the HPRR was analyzed in KOH and H2O2 medium at 298 K. The performance of the cathodes, in a single compartment, using a nickel plate as an anode was also investigated. The results showed that for the reduction reactions, electrodes developed with LSMMO have more significant catalytic activity than LSM after polarization, resulting in 32% higher current densities, lower electrical resistance after polarization, and a 21% increase in power density.

Highlights

Fuel cells are devices that convert chemical energy into electricity
This work aims firstly to produce strontium-doped lanthanum manganite mixed with molybdenum oxides by the Pechinni route, secondly to have electrodes with the produced oxides supported on carbon cloth, thirdly to characterize their microstructures and to evaluate the catalytic activity by voltammetry and electrochemical impedance spectroscopy for application as hydrogen peroxide reduction reaction (HPRR) and oxygen reduction reaction (ORR) electrocatalysts
The Rietveld refinement qualitative analysis indicates the presence of two phases in the lanthanum manganite strontium-doped perovskite without (LSM) sample: La0.5Sr0.5MnO3 and La2O3.28,29

Summary

Introduction

Fuel cells are devices that convert chemical energy into electricity. The electrochemical reactions that occur during their operation present high energy efficiency, low environmental and noise pollutions and can be used on mobile and portable devices.[1,2] Fuel cells are increasingly being studied due to the growing demand for cleaner, renewable and more affordable decentralized energy sources.[3,4]Direct liquid fuel cells, DLFCs, are an interesting power source for the automotive industry because of their higher energy densities than lithium-ion batteries.[4,5] Different liquids have been proposed as fuel to develop such fuel cells, for example, methanol (DMFCs),[6] ethylene glycol (DEGFCs),[7] glycerol (DGFCs),[8] formic acid (DFAFCs)[9] and hydrazine acid (DHFCs),[10] among others.[4]. Fuel cells are devices that convert chemical energy into electricity. The electrochemical reactions that occur during their operation present high energy efficiency, low environmental and noise pollutions and can be used on mobile and portable devices.[1,2] Fuel cells are increasingly being studied due to the growing demand for cleaner, renewable and more affordable decentralized energy sources.[3,4]. DLFCs, are an interesting power source for the automotive industry because of their higher energy densities than lithium-ion batteries.[4,5] Different liquids have been proposed as fuel to develop such fuel cells, for example, methanol (DMFCs),[6] ethylene glycol (DEGFCs),[7] glycerol (DGFCs),[8] formic acid (DFAFCs)[9] and hydrazine acid (DHFCs),[10] among others.[4] for applications in thin air-free systems, the use of oxygen is not feasible due to the difficulty of storage.[11]

Objectives

Results

Conclusion