1. Evaporated manganese films as a starting point for the preparation of thin-layer MnO x water-oxidation anodes
- Author
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Timothy N. Walter, Frances Kwok, Diego Gonzáles-Flores, Suzanne E. Mohney, Hamed Simchi, Philipp Kurz, Holger Dau, Ivelina Zaharieva, Jonas Ohms, Kayla A. Cooley, and Carolin E. Frey
- Subjects
Materials science ,X-ray diffractometry ,Inorganic chemistry ,Energy Engineering and Power Technology ,chemistry.chemical_element ,02 engineering and technology ,Substrate (electronics) ,Manganese ,010402 general chemistry ,Electrochemistry ,01 natural sciences ,Catalysis ,tunneling electron microscopy ,thin-layer MnOx ,Thin layers ,Electrolysis of water ,Renewable Energy, Sustainability and the Environment ,water-oxidation catalysts ,500 Naturwissenschaften und Mathematik::530 Physik::530 Physik ,X-ray absorption spectroscopy ,021001 nanoscience & nanotechnology ,Tin oxide ,0104 chemical sciences ,water oxidation anodes ,Fuel Technology ,chemistry ,0210 nano-technology ,Layer (electronics) ,scanning electron microscopy - Abstract
A novel method to prepare anodes for water electrolysis cells has been developed, which starts from layers of elemental manganese deposited by physical vapour deposition (PVD) on indium-doped tin oxide (ITO). Oxidation in dry air at 300 °C transforms this metallic Mn layer into a manganese(II)-rich MnOx coating (x = 1–1.3), which also contains a buried layer of an In–Sn alloy originating from reactions with the ITO support. The MnOx films are well connected to the underlying substrate and act as efficient catalysts for water-oxidation catalysis (WOC) at neutral pH. Detailed post-operando analyses using XRD, SEM, TEM and XAS revealed that the dense MnO/Mn3O4 film is virtually not affected by 2 h of electrochemical WOC at E ≈ +1.8 V vs. RHE, corresponding well to the observed good stability of catalytic currents, which is unusual for such thin layers of a MnOx catalyst. The current densities during electrolyses are so far low (i ≈ 50–100 μA cm−2 at pH 7), but optimization of the preparation process may allow for significant improvements. This new, rather easy, and adaptable preparation method for stable, thin-layer MnOx water-oxidation anodes could thus prove to be very useful for a variety of applications.
- Published
- 2019