Magnetron sputtered iridium oxide as anode catalyst for PEM hydrogen generation

Thin films of iridium oxide are deposited by reactive magnetron sputtering. The influence of oxygen partial pressure in the sputtering plasma on the composition, surface structure and morphology of the films has been studied by XRD, SEM, AFM and XPS analysis. An optimal combination of sputtering parameters yields stable microporous amorphous films with highly extended fractal surface. The electrochemical properties of these films are investigated in view of their application as catalysts for PEM water splitting, using the electrochemical techniques of cyclovoltammetry and steady state polarization. A morphology factor assessing the catalyst active surface for a series of sputtered samples with varying thickness/loading is determined and correlated to the catalytic efficiency. It has been proven that iridium oxide is a very efficient catalyst for oxygen evolution reaction (OER). The best performance with anodic current density of 0.3 A cm–2; at potential of 1.55 V (vs. RHE) shows the 500 nm thick film containing 0.2 mg cm-2; catalyst. These results combined with the established long-term mechanical stability of the sputtered iridium oxide films (SIROFs) prove the advantages of the reactive magnetron sputtering as simple and reliable method for preparation of catalysts with precisely controlled composition, loading, and surface characteristics.

Abstract licence: CC BY-NC

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