Session:

Due to its high energy density, hydrogen fuel shows promise is the decarbonization of freight transport. However, there remain challenges in the synthesis of hydrogen fuel. Electrocatalytic water splitting holds the potential to sustainably produce hydrogen fuel provided suitable catalysts are identified. Here, we present the high entropy aluminate spinel oxide (Fe_0.2Co_0.2Ni_0.2Cu_0.2Zn_0.2)Al₂O₄ (A⁵Al₂O₄) as catalyst for the for the oxygen evolution reaction (OER) in an alkaline electrolyte, and explore its electronic structure. In High entropy oxides (HEOs), numerous cations coexist in a single sublattice forming a solid solution throughout the crystalline solid. The sharing of a sublattice gives rise to unique, and even enhanced, properties including improved catalytic performance. Experimental measurements indicate A⁵Al₂O₄ has a bandgap far narrower than its parent phases. First principles calculations indicate that this narrowing of the bandgap is a consequence of the broadening of bands arising from the hybridization of the 3d states due to the variation of electronegativity across the 3d transition metal series. The observed narrowing of the bandgap in the high entropy spinel highlights a new method of engineering electronic structure using a high entropy approach to achieve desired material properties.

Co-Author(s): Ismaila Dabo (The Pennsylvania State University), Raymond Schaak (The Pennsylvania State University), Zhiqiang Mao (The Pennsylvania State University), Rowan Katzbaer (The Pennsylvania State University)

Francisco Marques dos Santos Vieira

Appearances