Journal
NANO RESEARCH
Volume 10, Issue 5, Pages 1819-1831Publisher
TSINGHUA UNIV PRESS
DOI: 10.1007/s12274-017-1511-9
Keywords
cobalt vacancies (V'(Co)); Co1-xS; oxygen evolution reaction; electrocatalysis; nanosheets
Categories
Funding
- National Natural Science Foundation of China [21631004, 21371053, 21573062]
- Project for Foshan Innovation Group [2014IT100062]
- Application Technology Research and Development Projects in Harbin [2013AE4BW051]
- International Science & Technology Cooperation Program of China [2014DFR41110]
- Foundation of Heilongjiang Province of China [QC2013C009]
- Excellent Youth of Heilongjiang University [JCL201501]
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Developing cost-efficient electrocatalysts for oxygen evolution is vital for the viability of H-2 energy generated via electrolytic water. Engineering favorable defects on the electrocatalysts to provide accessible active sites can boost the sluggish reaction thermodynamics or kinetics. Herein, Co1-xS nanosheets were designed and grown on reduced graphene oxide (rGO) by controlling the successive two-step hydrothermal reaction. A belt-like cobalt-based precursor was first formed with the assistance of ammonia and rGO, which were then sulfurized into Co1-xS by L-cysteine at a higher hydrothermal temperature. Because of the non-stoichiometric defects and ultrathin sheet-like structure, additional cobalt vacancies (V'(Co)) were formed/exposed on the catalyst surface, which expedited the charge diffusion and increased the electroactive surface in contact with the electrolyte. The resulting Co1-xS/rGO hybrids exhibited an overpotential as low as 310 mV at 10 mA.cm(-2) in an alkaline electrolyte for the oxygen evolution reaction (OER). Density functional theory calculations indicated that the V'(Co) on the Co1-xS/rGO hybrid functioned as catalytic sites for enhanced OER. They also reduced the energy barrier for the transformation of intermediate oxygenated species, promoting the OER thermodynamics.
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