Graphite-conjugation enhances porphyrin electrocatalysis
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
- Argonne National Lab. (ANL), Argonne, IL (United States); Illinois Inst. of Technology, Chicago, IL (United States)
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 O2 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 μA/cm2 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.
- Research Organization:
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- SC0014176
- OSTI ID:
- 1501360
- Journal Information:
- ACS Catalysis, Vol. 9, Issue 4; ISSN 2155-5435
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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