STUDY OF ACID STABILITY AND DEMETALLATION OF MANGANESE-NICKEL AND MANGANESE-IRON DUAL-ATOM ELECTROCATALYSTS IN GRAPHENE INTERIOR AND NANPOROUS STRUCTURES UNDER HYDROGEN FUEL CELL OPERATING CONDITIONS

• Main Author: Lukmanul Hakim, M
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/86797
• Institution: Institut Teknologi Bandung

This study evaluates the acid stability and demetallation mechanism of dual-atom catalysts (DAC) MnNi and MnFe within graphene structures for hydrogen fuel cell applications. Previous research has enriched the understanding of DAC stability in the operational environment of hydrogen fuel cells. This study focuses on the active site configurations of ortho and para at basal and edge positions (armchair/AGNR and zigzag/ZGNR), to observe the effect of active site conditions, both in the absence of adsorbates and when poisoned by O* or OH*, on catalyst stability across pH and potential ranges relevant to the Oxygen Reduction Reaction (ORR). The methodology combines energy calculations based on Density Functional Theory (DFT) with the Computational Hydrogen Electrode (CHE) approach to calculate the free energy of demetallation reaction candidates at active sites. The calculation results are mapped onto Pourbaix diagrams to assess the thermodynamic stability of DAC across various pH and potential levels. The results indicate that ortho and para configurations exhibit distinct stability profiles. The ortho configuration is generally stable in a clean state at high pH, both at interior and edge positions of graphene. However, for ORR in a alkaline pH environment, optimal stability for the ortho structure is only observed on the armchair edge. In contrast, the para configuration is more prone to poisoning by O* and OH* but remains stable at high pH within the ORR potential range, both at the interior and edge positions of graphene. Keywords: Dual atom catalysts, MnNi, MnFe, graphene, ORR, Density Functional Theory, Computational Hydrogen Electrode, acid stability