Abstract

Controlled Fe substitution through the Solid State Synthesis (argon condition) at the B site in the BaMn 1 x FeₓO 3 δ metal oxide system leads to significant improvements in the electrocatalytic activities for both the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER). When the iron content goes up, the crystal structure changes from hexagonal polytypes (4H BaMnO 3 δ , 10H BaMn 1/2 Fe 1/2 O 3 δ , and 10H BaMn 1/3 Fe 2/3 O 3 δ ) to a monoclinic perovskite type structure in BaFeO 3 δ . This change in structure is accompanied by a significant improvement in electrochemical performance. Compared to Mn rich compositions, BaFeO 3 δ has much lower overpotentials, less charge transfer resistance, higher current densities, and faster reaction kinetics. The results show how important it is to change th e amount of Fe in order to change the electronic structure and catalytic activity of perovskite oxides that are common on Earth. This study demonstrates that the world's second most abundant and cheapest metal, Fe induced structural reorganization, is a vi able approach for the development of high performance catalysts for water splitting, especially in the hexagonal structural framework, which is less investigated.

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