High active and easily prepared cobalt encapsulated in carbon nanotubes for hydrogen evolution reaction

We prepared M/CeO2 (M = Fe, Co or Ni) by coprecipitation method, and then fabricated M@CNT/CeO2 electrocatalysts through ethanol decomposition on M/CeO2. Experimental results showed that the activity of Co@CNT/CeO2 for hydrogen evolution reaction (HER) was much higher than that of Fe@CNT/CeO2 and Ni...

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Bibliographic Details
Published in:International journal of hydrogen energy 2020-02, Vol.45 (7), p.3948-3958
Main Authors: Xiao, Yupeng, Wang, Wenju, Wu, Qiao
Format: Article
Language:English
Subjects:
CNT
Ethanol decomposition
Hydrogen evolution
Nanomaterial
Non-precious metal
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Summary:We prepared M/CeO2 (M = Fe, Co or Ni) by coprecipitation method, and then fabricated M@CNT/CeO2 electrocatalysts through ethanol decomposition on M/CeO2. Experimental results showed that the activity of Co@CNT/CeO2 for hydrogen evolution reaction (HER) was much higher than that of Fe@CNT/CeO2 and Ni@CNT/CeO2, these experimental results were consistent with the density functional theory (DFT) calculation results. The electrocatalysts from ethanol decomposition on Co/CeO2 at 800 °C with different time were obtained, and their electrocatalytic activities for HER were discussed. Co@CNT-90 showed higher activity than others, when the reaction time exceeded 90 min, their HER activities declined gradually, because long-term ethanol decomposition caused decreased dispersion and thicker layers of carbon nanotube (CNT). To obtain a current density of 10 mA cm−2, overpotential of 181 mV was required for Co@CNT-90, and its polarization curve after 8000 cycles retained a similar performance to the initial polarization curve. The high activity and durability of Co@CNT-90 could be explained from the carbon-encapsulated-metal structure, thus metal was protected by carbon layers and prevented metal from contacting with electrolyte directly. XRD patterns, TEM images and experimental results proved that Co was well encapsulated by CNT. [Display omitted] •The electrocatalytic activity of Co@CNT/CeO2 for HER was related to the time of ethanol decomposition.•The overpotential of Co@CNT-90 reached 181 mV, and exhibited a good stability.•High activity of Co@CNT-90 was attributed to the excellent dispersity.
ISSN:0360-3199
1879-3487
DOI:10.1016/j.ijhydene.2019.12.018