Thermal optimization of manganese dioxide nanorods with enhanced ORR activity for alkaline membrane fuel cell

Electrochemical Science Advances

Saim Saher¹  M. Owais Khan²  Muhammad Ali Sikandar³  Tahir Nawaz⁴  Shahbaz Ahmad⁵  Affaq Qamar⁵  Abid Ullah⁵  Mushtaq Ahmed⁵ 

[1] Ariston Energy Solutions Peshawar Pakistan;Department Of Mechanical Engineering University of Engineering and Technology Peshawar Khyber Pakhtunkhwa Pakistan;Department of Civil Engineering CECOS University of IT & Emerging Sciences Peshawar Pakistan;U.S.‐Pakistan Center for Advanced Studies in Energy National University of Sciences and Technology Islamabad Pakistan;U.S.‐Pakistan Center for Advanced Studies in Energy University of Engineering and Technology Peshawar Khyber Pakhtunkhwa Pakistan;

关键词: alkaline fuel cell;    linear sweep voltammetry;    MnO2 nanorods;    oxygen reduction reaction;   

DOI  :  10.1002/elsa.202000032

来源: DOAJ

【 摘 要 】

Abstract In this study, pristine MnO2 catalyst was synthesized by hydrothermal technique and annealed at 400 and 600°C (MnO2@400°C and MnO2@600°C) transforming it into nanorods in a nitrogen atmosphere. The heat treatment process ameliorates the catalytic activity of the MnO2 catalyst by inducing oxygen vacancies. The catalyst is characterized by scanning electron microscope, and X‐ray diffraction, Fourier transforms infrared spectroscopy (FTIR), Electron paramagnetic resonance (EPR), and X‐ray Photoelectron Spectroscopy, whereas the oxygen reduction reaction (ORR) activity examined through rotating disc electrode and fuel cell test station. To elucidate the effect of sintering temperature on the MnO2 nanorods, the high angle annular dark‐field (HAADF) imaging was carried out on the samples. MnO2@400°C showed preeminent robustness to withstand austere alkaline environment during the experiment and possessed high electrocatalytic activity for the ORR with current density and onset potential values of 6.4 mA cm–2 and 0.80 V VS (RHE), respectively. The single‐cell test experiment of alkaline fuel cell delivered peak power density 81 mW/cm at 50°C. It is believed that this idiosyncratic behavior of MnO2 nanorods is due to the preferential growth on (211) and (310) indices and coexistence of optimized Mn4+/Mn3+ oxidation states as well as the creation of optimum oxygen vacancies on MnO2 nanorods. Moreover, the stretching of MnO2 nanorods occurs with increasing temperature and thus increasing the surface area to volume ratio. Thus thermal treatment shows that MnO2 is highly sensitive toward temperature variation and optimum ORR results can be obtained at adequate temperatures.

【 授权许可】

Unknown