Highly efficient nitrogen and carbon coordinated N-Co-C electrocatalysts on reduced graphene oxide derived from vitamin-B12 for the hydrogen evolution reaction
Journal
Journal of Materials Chemistry A
Journal Volume
7
Journal Issue
12
Pages
7179-7185
Date Issued
2019
Author(s)
Sabhapathy, P.
Liao, C.-C.
Chen, W.-F.
Chou, T.-C.
Shown, I.
Sabbah, A.
Lin, Y.-G.
Lee, J.-F.
Tsai, M.-K.
Chen, K.-H.
Abstract
Exploring electrocatalysts composed of earth-abundant elements for a highly efficient hydrogen evolution reaction (HER) is scientifically and technologically important for electrocatalytic water splitting. In this work, we report HER properties of acid treated pyrolyzed vitamin B12 supported on reduced graphene oxide (B12/G800A) that shows an extraordinarily enhanced catalytic activity with low overpotential (115 mV vs. RHE at 10 mA cm-2), which is better than that of most traditional nonprecious metal catalysts in acidic media. Stability tests through long-term potential cycles and at a constant current density confirm the exceptional durability of the catalyst. Notably, the B12/G800A catalyst exhibits extremely high turnover frequencies per cobalt site in acid, for example, 0.85 and 11.46 s-1 at overpotentials of 100 and 200 mV, respectively, which are higher than those reported for other scalable non-precious metal HER catalysts. Moreover, it has been conjectured that the covalency of Co-C and Co-N bonds affects HER activities by comparing the extended X-ray absorption fine structure (EXAFS) spectra of the B12/G800A. High-temperature treatment can modify the Co-corrin structure of B12 to form Co-C bonds along with Co-N, which broadens the band of cobalt, essentially lowering the d-band center from its Fermi level. The lower d-band center leads to a moderate hydrogen binding energy, which is favorable for hydrogen adsorption and desorption. © 2019 The Royal Society of Chemistry.
SDGs
Other Subjects
Binding energy; Catalyst activity; Cobalt; Coordination reactions; Durability; Electrocatalysts; Extended X ray absorption fine structure spectroscopy; Graphene; Nitrogen; X ray absorption; Constant current density; Enhanced catalytic activity; Extended x-ray absorption fine structure spectrum; High temperature treatments; Hydrogen evolution reactions; Long-term potential; Non-precious metal catalysts; Reduced graphene oxides; Gas adsorption
Publisher
Royal Society of Chemistry
Type
journal article