Computational Modeling of Layered Structure of IrO2 and IrOOH

Abstract

The increasing demand for clean energy has intensified research into materials that can enhance the efficiency of electrochemical processes such as water electrolysis. Layered transition metals oxides and oxyhydroxides have drawn interest because of their versatility as an electrocatalyst. Iridium-based catalysts have gained particular interest for their multivalent state among these electrocatalysts. Here, we examine the electronic and structural characteristics of layered IrO2 and IrOOH. This thesis presents a comprehensive computational study of the structural, electronic, and vibrational properties of IrO2 and IrOOH, using Density Functional Theory (DFT) with van der Waals (vdW) corrections to investigate and model the structures. Using functionals such as PBE+rVV10L and SCAN+rVV10, various stacking arrangements (AA, AB, AA′, and AB′) for IrO2 were investigated, with AA stacking consistently predicted as the lowest energetically configuration. The minimal energy differences between AA and AB′ stackings suggest the potential for stacking faults. Additionally, the impact of structural distortions on the dynamical stability and electronic properties of IrO2 was explored, revealing that distortions can induce a transition from metallic to semiconducting behavior. IrOOH is modeled by hydrogenating the IrO2 structure, and both pristine and distorted configurations were analyzed. The electronic band structure predicts that IrOOH behaves as a semiconductor, where the distorted structure reverts to pristine-like. This work deepens our understanding of the structural and electronic properties that contribute to modeling the layered structures of IrO2 and IrOOH. Such insights are expected to be crucial for future theoretical and experimental efforts to optimize the materials for green energy technologies, including water splitting and other electrochemical applications.