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Highly Active and Stable Hybrid Catalyst of Cobalt-Doped FeS2 Nanosheets–Carbon Nanotubes for Hydrogen Evolution Reaction

Wang, Di-Yan, Gong, Ming, Chou, Hung-Lung, Pan, Chun-Jern, Chen, Hsin-An, Wu, Yingpeng, Lin, Meng-Chang, Guan, Mingyun, Yang, Jiang, Chen, Chun-Wei, Wang, Yuh-Lin, Hwang, Bing-Joe, Chen, Chia-Chun, Dai, Hongjie
Journal of the American Chemical Society 2015 v.137 no.4 pp. 1587-1592
X-ray diffraction, adsorption, carbon nanotubes, catalysts, catalytic activity, clean energy, cobalt, cost effectiveness, durability, electrochemistry, hydrogen production, iron, nanosheets, platinum, pyrite, spectroscopy
Hydrogen evolution reaction (HER) from water through electrocatalysis using cost-effective materials to replace precious Pt catalysts holds great promise for clean energy technologies. In this work we developed a highly active and stable catalyst containing Co doped earth abundant iron pyrite FeS₂ nanosheets hybridized with carbon nanotubes (Fe₁–ₓCoₓS₂/CNT hybrid catalysts) for HER in acidic solutions. The pyrite phase of Fe₁–ₓCoₓS₂/CNT was characterized by powder X-ray diffraction and absorption spectroscopy. Electrochemical measurements showed a low overpotential of ∼0.12 V at 20 mA/cm², small Tafel slope of ∼46 mV/decade, and long-term durability over 40 h of HER operation using bulk quantities of Fe₀.₉Co₀.₁S₂/CNT hybrid catalysts at high loadings (∼7 mg/cm²). Density functional theory calculation revealed that the origin of high catalytic activity stemmed from a large reduction of the kinetic energy barrier of H atom adsorption on FeS₂ surface upon Co doping in the iron pyrite structure. It is also found that the high HER catalytic activity of Fe₀.₉Co₀.₁S₂ hinges on the hybridization with CNTs to impart strong heteroatomic interactions between CNT and Fe₀.₉Co₀.₁S₂. This work produces the most active HER catalyst based on iron pyrite, suggesting a scalable, low cost, and highly efficient catalyst for hydrogen generation.