(656d) Stability and Activity of IrO2-Based Homogeneous, Heterogeneous, and Hybrid Water Oxidation Catalysts

Electrochemical production of hydrogen gas is a promising energy storage technology but is limited by the slow kinetics of the oxygen evolution reaction (OER). Homogeneous and heterogenous Ir and Ru based water oxidation catalysts (WOCs) have been the most effective at catalyzing OER [1,2]; however, both of these elements face scarcity, cost, and stability issues [1-4]. One proposed method for improving the use of these precious metals is anchoring the homogeneous catalyst onto a solid support surface, via a linker molecule, to create a so-called hybrid or immobilized catalyst that could have the benefits of both homogeneous and heterogeneous catalysts [5]. Here, we present a comprehensive computational study of the stability and activity of hybrid Ir-based WOCs and compare them to the corresponding homogeneous and heterogeneous catalysts. We show that in the presence of an IrO₂ or TiO₂(110) surface, all investigated homogeneous molecular species (monomer, dimer, and infinite) will anchor to the surface independently of the surface termination and that their reactivity is related to their stability. This work in hybrid catalysts will serve as a bridge between the heterogeneous catalyst and homogeneous catalyst communities and understanding the chemistry behind these mechanisms can further the development of efficient and stable WOCs.

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