Theory-driven design of high-valence metal sites for water oxidation confirmed using in situ soft X-ray absorption [electronic resource]

• Ngôn ngữ: eng
• Ký hiệu phân loại: 541.3 Miscellaneous topics in physical chemistry
• Thông tin xuất bản: Washington, D.C. : Oak Ridge, Tenn. : United States. Dept. of Energy. Office of Science ; Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy, 2017
• Mô tả vật lý: Size: p. 149-154 : , digital, PDF file.
• Bộ sưu tập: Metadata
• ID: 255688
• Chủ đề: 1. 30 direct energy conversion; 2. 36 materials science; 3. 37 inorganic, organic, physical, and analytical chemistry; 4. Electrocatalysis; 5. Energy; 6. Fluorescence spectroscopy; 7. In situ soft x-ray absorption

Tóm tắt

 The efficiency with which renewable fuels and feedstocks are synthesized from electrical sources is limited at present by the sluggish oxygen evolution reaction (OER) in pH-neutral media. Here, we took the view that generating transition metal sites with high valence at low applied bias should improve the activity of neutral OER catalysts. Using density functional theory, we find that the formation energy of desired Ni<
 sup>
 4+<
 /sup>
  sites is systematically modulated by incorporating judicious combinations of Co, Fe and non-metal phosphorus. Here we synthesized NiCoFeP oxyhydroxides and probed their oxidation kinetics by employing in situ soft X-ray absorption (sXAS). In situ sXAS studies of neutral-pH OER catalysts indicate ready promotion of Ni<
 sup>
 4+<
 /sup>
  under low overpotential conditions. NiCoFeP catalyst outperforms IrO<
 sub>
 2<
 /sub>
  and retains its performance following 100 hours of operation. We showcase NiCoFeP in a membrane-free CO<
 sub>
 2<
 /sub>
  electroreduction system that achieves a 1.99 V cell voltage at 10 mA cm<
 sup>
 -2<
 /sup>
 , reducing CO<
 sub>
 2<
 /sub>
  into CO and oxidizing H<
 sub>
 2<
 /sub>
 O to O<
 sub>
 2<
 /sub>
  with a 64% electricity-to-chemical-fuel efficiency.