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Journal Article
Flexible molecular precursors for selective decomposition to nickel sulfide or nickel phosphide for water splitting and supercapacitance
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Abstract: Herein, the synthesis of three nickel(II) dithiophosphonate complexes of the type [Ni{S2P(OR)(4-C6H4OMe)}2] [R=H (1), C3H7 (2)] and [Ni{S2P(OR)(4-C6H4OEt}2] [R=(C6H5)2CH (3)] is described; their structures were confirmed by single-crystal X-ray studies. These complexes were subjected to surfactant/solvent reactions at 300 °C for one hour as flexible molecular precursors to prepare either nickel sulfide or nickel phosphide particles. The decomposition of complex 2 in tri-octylphosphine oxide/1-octadecene (TOPO/ODE), TOPO/tri-n-octylphosphine (TOP), hexadecylamine (HDA)/TOP, and HDA/ODE yielded hexagonal NiS, Ni2P, Ni5P4, and rhombohedral NiS, respectively. Similarly, the decomposition of complex 1 in TOPO/TOP and HDA/TOP yielded hexagonal Ni2P and Ni5P4, respectively, and that of complex 3 in similar solvents led to hexagonal Ni5P4, with TOP as the likely phosphorus provider. Hexagonal NiS was prepared from the solvent-less decomposition of complexes 1 and 2 at 400 °C. NiS (rhom) had the best specific supercapacitance of 2304 F g−1 at a scan rate of 2 mV s−1 followed by 1672 F g−1 of Ni2P (hex). Similarly, NiS (rhom) and Ni2P (hex) showed the highest power and energy densities of 7.4 kW kg−1 and 54.16 W kg−1 as well as 6.3 kW kg−1 and 44.7 W kg−1, respectively. Ni5P4 (hex) had the lowest recorded overpotential of 350 mV at a current density of 50 mA cm−2 among the samples tested for the oxygen evolution reaction (OER). NiS (hex) and Ni5P4 (hex) had the lowest overpotentials of 231 and 235 mV to achieve a current density of 50 mA cm−2, respectively, in hydrogen evolution reaction (HER) examinations.
Citation: Ayom, G.E., Khan, M.D., Ingsel, T., Lin, W., Gupta, R.K., Zamisa, S.J., Van Zyl, W.E. and Revaprasadu, N., 2020. Flexible molecular precursors for selective decomposition to nickel sulfide or nickel phosphide for water splitting and supercapacitance. Chemistry–A European Journal, 26(12), pp.2693-2704.
Publication Place: New York, United States
Other: https://doi.org/10.1002/chem.201904583
Journal Title: Chemistry - A European Journal
Journal Issue / Part Number: 26 / 12
Peer reviewed: Yes
International Conference: issn
Keynote / Plenary: issn
In Proceedings: issn
ISSN: 1521-3765 (online)
Other: https://doi.org/10.1002/chem.201904583
Publisher: Wiley
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