Applied Surface Science | 2021

Effective alkaline water electrolysis on nwMnO2-nsNi(OH)2 composite electrode via lattice oxygen participant adsorbate evolving mechanism



Abstract To improve and maintain the oxygen evolution reaction (OER) performance of MnO2 in water electrolysis for a long time, this study attempts to utilize Ni(OH)2 nanosheets (ns), which have excellent electrochemical properties. Nanocomposites of MnO₂ and Ni(OH)2 were directly grown on a carbon paper (CP) electrode using hydrothermal synthesis. The MnO2 nanowires (nw) appeared to be wrapped by the Ni(OH)2 nanosheets in the MnO2-Ni(OH)2 composites. The MnO2-Ni(OH)2 composite electrode exhibited better OER performance than the nwMnO2@CP or nsNi(OH)2@CP electrodes. In particular, in a 1.0\xa0M KOH alkaline electrolyte, the 1.0 nwMnO2-1.0 nsNi(OH)2@CP electrode showed the highest OER performance with a cell potential of 1.64\xa0V and Tafel slope of 68\xa0mV dec−1 at a 10\xa0mA\xa0cm−2 of current density (η\xa0=\xa00.41\xa0V). The X-ray photoelectron spectroscopy of nwMnO2-nsNi(OH)2@CP before and after the OER revealed the formation of more oxygen vacancies, which served as OH-adsorption sites, leading to higher OER activity. The stability of the 1.0 nwMnO2-1.0 nsNi(OH)2@CP electrode was demonstrated through 300\xa0h-OER long-term tests, which yielded a high Faradaic efficiency of 96.2%. The lattice oxygen transfer plays a significant role in enhancing the intrinsic activity of catalysts during OER. The synergy between nwMnO2 and nsNi(OH)2 accompanies a lattice oxygen participant adsorbate evolving mechanism.

Volume None
Pages 150281
DOI 10.1016/J.APSUSC.2021.150281
Language English
Journal Applied Surface Science

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