High-performance iron (III) oxide electrocatalyst for water oxidation in strongly acidic media

Kwong, Wai LingUppsala universitet,Molekylär biomimetik,Molecular Biomimetics (författare)

Stable and efficient oxygen evolution reaction (OER) catalysts for the oxidation of water to dioxygen in highly acidic media are currently limited to expensive noble metal (Ir and Ru) oxides since presently known OER catalysts made of inexpensive earth-abundant materials generally suffer anodic corrosion at low pH. In this study, we report that a mixed-polymorph film comprising maghemite and hematite, prepared using spray pyrolysis deposition followed by low-temperature annealing, showed a sustained OER rate (>24 h) corresponding to a current density of 10 mA cm−2 at an initial overpotential of 650 mV, with a Tafel slope of only 56 mV dec−1 and near-100% Faradaic efficiency in 0.5 M H2SO4 (pH 0.3). This performance is remarkable, since iron (III) oxide films comprising only maghemite were found to exhibit a comparable intrinsic activity, but considerably lower stability for OER, while films of pure hematite were OER-inactive. These results are explained by the differences in the polymorph crystal structures, which cause different electrical conductivity and surface interactions with water molecules and protons. Our findings not only reveal the potential of iron (III) oxide as acid-stable OER catalyst, but also highlight the important yet hitherto largely unexplored effect of crystal polymorphism on electrocatalytic OER performance.

Lee, Cheng ChooUmeå universitet,Institutionen för fysiologisk botanik,Umeå Core Facility for Electron Microscopy, Umeå University, 90187 Umeå, Sweden(Swepub:umu)chch0027 (författare)
Shchukarev, AndreyUmeå universitet,Kemiska institutionen,Department of Chemistry, Kemiskt Biologiskt Centrum (KBC), Umeå University, 90187 Umeå, Sweden(Swepub:umu)ansh0001 (författare)
Björn, ErikUmeå universitet,Kemiska institutionen,Department of Chemistry, Kemiskt Biologiskt Centrum (KBC), Umeå University, 90187 Umeå, Sweden(Swepub:umu)erkbjn97 (författare)
Messinger, JohannesUppsala universitet,Umeå universitet,Kemiska institutionen,Department of Chemistry-Ångström Laboratory, Molecular Biomimetics, Uppsala University, 75120 Uppsala, Sweden,Molekylär biomimetik,Department of Chemistry, Kemiskt Biologiskt Centrum (KBC), Umeå University, 90187 Umeå, Sweden(Swepub:uu)johme269 (författare)
Uppsala universitetMolekylär biomimetik (creator_code:org_t)

Av författaren/redakt...: Kwong, Wai Ling; Lee, Cheng Choo; Shchukarev, Andr ...; Björn, Erik; Messinger, Johan ...

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