IrOOH nanosheets as acid stable electrocatalysts for the oxygen evolution reaction

In solids, heterogeneous catalysis is inherently bound to reactions on the surface. Yet, atomically efficient preparation of specific surfaces and the characterization of their properties are impeding its applications towards a clean energy future. Here, we present the synthesis of single layered IrOOH nanosheets and investigations of their structure as well as their electrochemical properties towards oxygen evolution under aqueous acidic conditions. The nanosheets are synthesized by treating bulk IrOOH with a tetrabutylammonium hydroxide solution and subsequent washing. Electron diffraction shows that the triangular arrangement of the edge sharing Ir(O,OH)(6) octahedra found in the layers of bulk IrOOH is retained after exfoliation into single layers. When incorporated as an active component in Ti electrodes, the nanosheets exhibit a Tafel slope of 58(3) mV dec(-1) and an overpotential of eta(-2)(10 mA cm) = 344(7) mV in 0.1 M HClO4, while retaining the trivalent oxidation state of iridium. They outperform bulk rutile-IrO2 and bulk IrOOH as electrocatalytic water oxidation catalysts under the same conditions. The results of this study on the structure-property relationships of low valence IrOOH nanosheets offer new pathways for the development of atom efficient, robust and highly active oxygen evolution catalysts.

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Filip Mateusz Podjaski
2018
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https://infoscience.epfl.ch/record/262242?ln=fr

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Concepts associés (2)

Oxygen evolution

Oxygen evolution is the process of generating molecular oxygen (O2) by a chemical reaction, usually from water. Oxygen evolution from water is effected by oxygenic photosynthesis, electrolysis of water, and thermal decomposition of various oxides. The biological process supports aerobic life. When relatively pure oxygen is required industrially, it is isolated by distilling liquefied air. Oxygen evolving complex Photosynthetic oxygen evolution is the fundamental process by which oxygen is generated in the earth's biosphere.

Nanosheet

A nanosheet is a two-dimensional nanostructure with thickness in a scale ranging from 1 to 100 nm. A typical example of a nanosheet is graphene, the thinnest two-dimensional material (0.34 nm) in the world. It consists of a single layer of carbon atoms with hexagonal lattices. Silicon nanosheets are being used to prototype future generations of small (5 nm) transistors. Carbon nanosheets (from hemp) may be an alternative to graphene as electrodes in supercapacitors. The most commonly used nanosheet synthesis methods use a bottom-up approach, e.