Highly Enhanced Electrochemical Water Oxidation Reaction over Hyperfine β-FeOOH(Cl):Ni Nanorod Electrode by Modification with Amorphous Ni(OH)2

Abstract

received her bachelor and master degrees from Nara Women's University. She joined Toyota CRDL in 1992 and received he Ph.D. Degree from Tokyo Institute of Technology in 2009. Currently, she is a senior researcher of the Morikawa Senior Fellow Laboratory in Toyota CRDL. She has been working on development of inorganic catalyst materials for artificial photosynthesis. Takeshi MorikawaTakeshi Morikawa received his bachelor and master degrees from Nagoya University. He joined Toyota CRDL in 1989 and received his Ph.D. Degree in 2005. He has been working on development of sensors for automotive controls, magnetic materials, semiconductor photocatalyst, and CO 2 recycling systems by artificial photosynthesis. He is currently a manager of the Morikawa Senior Fellow Laboratory in Toyota CRDL. AbstractA highly crystalline, 10 nm-sized red rust water oxidation catalyst composed of pure β-phase FeOOH(Cl) nanorods (ca. 3 © 13 nm) doped with Ni ions (β-FeOOH(Cl):Ni) and surfacemodified with amorphous Ni(OH) 2 (a-Ni(OH) 2 , at a Ni to Fe ratio of 22 at.%) was synthesized by a facile one-pot process at room temperature. The overpotential during the electrochemical oxygen evolution reaction (OER) over the β-FeOOH:Ni/ a-Ni(OH) 2 stacked nanorod anodes was 170 mV, and an OER current of 10 mA/cm 2 was obtained at an overpotential of 430 mV in a 0.1 M KOH solution. X-ray absorption fine structure analysis, Mössbauer spectroscopy, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, X-ray diffraction and impedance spectroscopy suggested that surface modification with the a-Ni(OH) 2 lowered the OER overpotential of β-FeOOH(Cl):Ni, resulting in the very high current density at low potential compared with Fe-rich oxide and oxyhydroxide electrodes reported previously. Mössbauer spectroscopy suggested interaction between Fe and Ni species, which may be crucial evidence for the enhanced activity in the Fe-rich OER system.

Solar-driven CO2 to CO reduction utilizing H2O as an electron donor by earth-abundant Mn–bipyridine complex and Ni-modified Fe-oxyhydroxide catalysts activated in a single-compartment reactor

“…[13][14][15][16][17][18][19] We have recently reported akaganeite-type iron oxyhydroxide hyperfine nanorod doped with 1 at% nickel (b-FeOOH:Ni) surface-modified with 21 at% amorphous nickel hydride (a-Ni(OH) 2 ) in which Ni amounts are defined as Ni/Fe ratio (hereinafter referred to as b-FeOOH:Ni/a-Ni(OH) 2 ). 19 b-FeOOH: Ni/a-Ni(OH) 2 exhibited higher performance than other Fe-based oxide and oxyhydroxide materials, and an overpotential of 430 mV (1.66 V vs. RHE) at 10 mA cm À2 was observed during the OER under Toyota Central Research and Development Laboratories, Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192, Japan. E-mail: takeo-arai@mosk.tytlabs.co.jp † Electronic supplementary information (ESI) available.…”

“…NiOOH was described as an unsuitable electrocatalyst for applications in neutral or moderately alkaline pH (in the range 7-11). In the case of b-FeOOH:Ni/a-Ni(OH) 2 , 19 it is considered that the amorphous Ni(OH) 2 on b-FeOOH:Ni influences the pH dependence of the OER activity. Cathodic peaks were observed at +1.36 V and +1.40 V (vs. RHE) in 1 M and 0.1 M KOH solutions, respectively ( Fig.…”

High-pressure synthesis of ε-FeOOH from β-FeOOH and its application to the water oxidation catalyst

“…25 C). [3][4][5] This method provides highly crystalline and uniform b-FeOOH nanorods with diameters of 3 nm and lengths of 15 nm, [3][4][5] owing to the typical advantages of the Ostwald ripening method. 51 As shown in Fig.…”

“…One of the polymorphs of FeOOH, namely, b-FeOOH (akaganeite), has attracted interest in highly diverse elds. In the 20th century, it was examined in the context of the atmospheric rusting of iron and steel, 1,2 whereas it is currently being investigated as a catalyst for water oxidation (oxygen evolution reaction; OER) [3][4][5][6][7] or as a negative electrode for Li-and Na-ion batteries. [8][9][10][11] Beside applications to functional materials, b-FeOOH has been received considerable attention in the elds of earth and space sciences and natural history because it was also discovered in the Gusev crater and the Meridiani Planum on Mars 12,13 and in the cannon shot of the Mary Rose, King Henry VIII's shipwrecked agship.…”

“…Regarding the OER catalyst, materials synthesized from b-FeOOH under HP/HT conditions could offer a wide range of material options to enhance OER performance, because current studies on the FeOOH polymorphs focus on fabricating composite electrodes or heterodoping. [3][4][5][6][7][44][45][46] Furthermore, earth-abundant catalysts such as Fe-based compounds are required to realize the global scalability within the framework of sustainable energy technologies. Note that the OER activities of the HP/HT phases of b-FeOOH and 3-FeOOH have not been reported thus far, including theoretical calculations on FeOOH polymorphs.…”