Graphite-conjugation enhances porphyrin electrocatalysis [electronic resource]

• Tác giả: United States, United States. Dept. of Energy. Office of Science
• Ngôn ngữ: eng
• Ký hiệu phân loại: 666.3 Pottery
• Mô tả vật lý: Size: p. 3667-3671 : , digital, PDF file.
• Bộ sưu tập: Báo, Tạp chí
• ID: 255640
• Chủ đề: 1. 30 direct energy conversion; 2. 37 inorganic, organic, physical, and analytical chemistry; 3. Electron transfer; 4. Heterogeneous electrocatalysis; 5. Molecular electrocatalysis; 6. Oxygen reduction; 7. Porphyrin; 8. Supported catalyst

Tóm tắt

 We synthesize porphyrins that are strongly electronically coupled to carbon electrodes by condensing diaminoporphyrin derivatives onto o-quinone moieties native to graphitic carbon surfaces. X-ray photoelectron and absorption spectroscopies along with electrochemical data establish the formation of a high-fidelity conjugated pyrazine linkage to the surface with preservation of the metalloporphyrin scaffold. Using the O<
 sub>
 2<
 /sub>
  reduction reaction (ORR) as a probe, we find that conjugation dramatically promotes the rate of catalysis. A graphite-conjugated Co porphyrin, GCC-CoTPP, displays an onset current of 10 ?A/cm<
 sup>
 2<
 /sup>
  at 0.72 V versus the reversible hydrogen electrode, whereas a non-conjugated amide-linked Co-porphyrin onsets at 0.66 V. This corresponds to an order of magnitude enhancement in the activation-controlled turnover frequencies for ORR upon conjugation. Conclusively, this work establishes a versatile platform for examining the emergent reactivity of porphyrins strongly coupled to metallic electrodes.