Mukai K, Suzuki TM, Uyama T, Nonaka T, Morikawa T, Yamada I. High-pressure synthesis of ε-FeOOH from β-FeOOH and its application to the water oxidation catalyst.
RSC Adv 2020;
10:44756-44767. [PMID:
35516263 PMCID:
PMC9058670 DOI:
10.1039/d0ra09895g]
[Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2020] [Accepted: 11/25/2020] [Indexed: 01/01/2023] Open
Abstract
Research on materials under extreme conditions such as high pressures provides new insights into the evolution and dynamics of the earth and space sciences, but recently, this research has focused on applications as functional materials. In this contribution, we examined high-pressure/high-temperature phases of β-FeO1−x(OH)1+xClx with x = 0.12 (β-FeOOH) and their catalytic activities of water oxidation, i.e., oxygen evolution reaction (OER). Under pressures above 6 GPa and temperatures of 100–700 °C, β-FeOOH transformed into ε-FeOOH, as in the case of α-FeOOH. However, the established pressure–temperature phase diagram of β-FeOOH differs from that of α-FeOOH, probably owing to its open framework structure and partial occupation of Cl− ions. The OER activities of ε-FeOOH strongly depended on the FeOOH sources, synthesis conditions, and composite electrodes. Nevertheless, one of the ε-FeOOH samples exhibited a low OER overpotential compared with α-FeOOH and its parent β-FeOOH, which are widely used as OER catalysts. Hence, ε-FeOOH is a potential candidate as a next-generation earth-abundant OER catalyst.
Research on materials under extreme conditions such as high pressures provides new insights into the evolution and dynamics of the earth and space sciences, but recently, this research has focused on applications as functional materials.![]()
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