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Calcium containing iron oxide as an efficient and robust catalyst in (photo-)electrocatalytic water oxidation at neutral pH†
Sustainable Energy & Fuels ( IF 5.6 ) Pub Date : 2017-11-02 00:00:00 , DOI: 10.1039/c7se00447h
Hung-Chun Chiu,Wei-Hsiang Huang,Liang-Ching Hsu,Yan-Gu Lin,Yi-Hsuan Lai,Chia-Yu Lin

We report on calcium containing iron oxide thin films (CaFeOx), prepared by spin-coating and a follow-up annealing process under mild condition, as an efficient and robust catalyst in electrocatalytic and photoelectrocatalytic water oxidation at neutral pH. Thin films prepared without calcium are essentially crystalline γ-Fe2O3, but those prepared with calcium are amorphous, and with optimal calcium content, the resultant film consists of a short-range order γ-Fe2O3 domain embedded in an amorphous Ca2Fe2O5 matrix. CaFeOx prepared with optimal calcium content decomposes upon exposure to phosphate, resulting in the leaching of surface calcium and formation of redox-active iron phosphate, which prevents the loss of active iron species from etching by protons released from the water oxidation process. The amorphous nature and in situ formation of iron phosphate render CaFeOx with high activity and stability under high turnover conditions, reaching 10 mA cm−2 at an overpotential (η) of ∼650 mV with a small increase in η (∼30 mV) over 2 h electrolysis in phosphate buffer (1.0 M, pH 7). When being integrated onto a BiVO4 photoanode, CaFeOx greatly improves the kinetics of the OER and interfacial hole transfer at BiVO4, resulting in remarkable enhancement in its photocurrent response and photostability.

中文翻译:

含钙的氧化铁可在中性pH值下作为(光)电催化水氧化的有效和强固催化剂

我们报告了在温和条件下通过旋涂和后续退火工艺制备的含钙氧化铁薄膜(CaFeO x),作为在中性pH值下电催化和光电催化水氧化的有效和强大的催化剂。无钙制备的薄膜基本上是结晶γ-的Fe 2 ö 3,但那些与钙制备是无定形的,并具有最佳的钙含量,将所得膜由短程有序的γ-的Fe 2 ö 3嵌入在无定形结构域Ca 2 Fe 2 O 5基质。CaFeO X以最佳钙含量制备的磷酸钙在暴露于磷酸盐时会分解,导致表面钙的浸出并形成氧化还原活性磷酸铁,从而防止了水氧化过程释放出的质子腐蚀掉活性铁。磷酸铁的无定形性质和原位形成使得CaFeO x在高周转条件下具有高活性和稳定性,在〜650 mV的过电势(η)时达到10 mA cm -2,而η(〜30 mV)的增加很小。在磷酸盐缓冲液(1.0 M,pH 7)中电解2小时。当集成到BiVO 4光电阳极中时,CaFeO x大大改善了BiVO 4的OER动力学和界面空穴转移,从而显着提高了其光电流响应和光稳定性。
更新日期:2017-11-02
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