IrO₂-TiO₂: A High-Surface-Area, Active, and Stable Electrocatalyst for the Oxygen Evolution Reaction

Abstract

The utilization and development of efficient water electrolyzers for hydrogen production is currently limited due to the sluggish kinetics of the anodic processthe oxygen evolution reaction (OER). Moreover, state of the art OER catalysts contain high amounts of expensive and low-abundance noble metals such as Ru and Ir, limiting their large-scale industrial utilization. Therefore, the development of low-cost, highly active, and stable OER catalysts is a key requirement toward the implementation of a hydrogen-based economy. We have developed a synthetic approach to high-surface-area chlorine-free iridium oxide nanoparticles dispersed in titania (IrO2-TiO2), which is a highly active and stable OER catalyst in acidic media. IrO2-TiO2 was prepared in one step in molten NaNO3 (Adams fusion method) and consists of ca. 1–2 nm IrO2 particles distributed in a matrix of titania nanoparticles with an overall surface area of 245 m2 g–1. This material contains 40 molM % of iridium and demonstrates improved OER activity and stability in comparison to the commercial benchmark catalyst and state of the art high-surface-area IrO2. Ex situ characterization of the catalyst indicates the presence of iridium hydroxo surface species, which were previously associated with the high OER activity. Operando X-ray absorption studies demonstrate the evolution of the surface species as a function of the applied potential, suggesting the conversion of the initial hydroxo surface layer to the oxo-terminated surface via anodic oxidation (OER regime).

Current Challenges in Catalyst Development for PEM Water Electrolyzers

“…The high electrochemical potential on the anode side of > 1.4 V, however, precludes the use of carbon supports which would get oxidized to CO 2 under these conditions , . On the other hand, titanium dioxide (TiO 2 ) is a stable, commercially available, and inexpensive material , and is frequently used as a catalyst support for Ir , . However, a relatively high amount of Ir or IrO 2 (> 40 wt %) is required to generate sufficient electric conductivity by forming a contiguous network/film of Ir or IrO 2 nanoparticles , , since TiO 2 itself is not conductive.…”

Layered TiO2 Nanosheet‐Supported NiCo2O4 Nanoparticles as Bifunctional Electrocatalyst for Overall Water Splitting

“…[10,11,19,21,22] Therefore, recently much research has been carried out for developing carbon-free electrocatalysts especially by using 3d transition metal oxides and hydroxides. [16,[23][24][25][26][27] Noticeable changes in the OER activity of these materials has been observed due to the crystalline phases, surfaces, heterostructures and morphology of nanoparticles. Therefore, it is indeed of great importance to designing an active and stable transition metal-based electrocatalyst for the overall water splitting remains as one of the pre-eminent tasks in this field of research.…”

Free‐Sustaining Three‐Dimensional S235 Steel‐Based Porous Electrocatalyst for Highly Efficient and Durable Oxygen Evolution

“…[6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] However,t he efficiencyo ft his methodi sm ainly restricted by the sluggish anodic oxygen evolution reaction (OER), the rate-limitings tep for overall water splitting, which involves four sequential proton-coupled electron-transfer steps and the formation of an oxygenoxygen bond. [30,31] However, scarcity,h igh acquisition costs, and poor performance over long-term OER measurements in alkaline solution hamper their suitability for widespread practical applications. [30,31] However, scarcity,h igh acquisition costs, and poor performance over long-term OER measurements in alkaline solution hamper their suitability for widespread practical applications.…”