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Phase and composition controlled synthesis of cobalt sulfides hollow nanospheres for electrocatalytic water splitting

Abstract

Developing cheap, highly efficient and stable electrocatalysts for both oxygen and hydrogen evolution (OER and HER) is extremely meaningful to realize large-scale implementation of water splitting technology. Herein, we report the phase and composition controlled synthesis of cobalt sulfides (CoSx) hollow nanospheres (HNSs) and their catalytic efficiencies for hydrogen and oxygen evolution in alkaline media. Three CoSx compounds, i.e., Co9S8, Co3S4, CoS2 HNSs, are precisely synthesized simply by adjusting the molar ratio of carbon disulfide to cobalt acetate in a facile solution-based strategy. Electrochemical results reveal that the as-prepared CoS2 HNSs exhibit superior OER and HER catalytic performance than Co9S8 and Co3S4 HNSs in 1.0 M KOH, with overpotentials of 290 mV for OER and 193 mV for HER at 10 mA cm-2, and corresponding Tafel slopes of 57 and 100 mV dec-1, respectively. In addition, the CoS2 HNSs exhibit remarkable long-term catalytic durability, which is even superior than precious metal catalysts of RuO2 and Pt/C. Moreover, the alkaline electrolyzer assembled with CoS2 HNSs as both anode and cathode materials can approach 10 mA cm-2 at a low cell voltage of 1.54 V at 60°C with the faradaic efficiency of 100 % for overall water splitting. Further analysis demonstrate that the surface morphology, crystallographic structure and coordination environment of Con+ active sites in combination determine the HER/OER activities in synthesized binary CoSx series, which would provides insight into the rational design of transition metal chalcogenides for highly efficient hydrogen and oxygen-involved electrocatalysis.

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Supplementary files

Publication details

The article was received on 18 Dec 2017, accepted on 31 Jan 2018 and first published on 01 Feb 2018


Article type: Paper
DOI: 10.1039/C7NR09424H
Citation: Nanoscale, 2018, Accepted Manuscript
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    Phase and composition controlled synthesis of cobalt sulfides hollow nanospheres for electrocatalytic water splitting

    X. Ma, W. Zhang, Y. Deng, C. Zhong, W. Hu and X. Han, Nanoscale, 2018, Accepted Manuscript , DOI: 10.1039/C7NR09424H

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