Phase transformations in the nickel phosphide system induced by transition-metal doping and electro-catalytic study Neerish Revaprasadu University of Zululand, South Africa The synthesis of pure-phase functional nickel phosphides is desired today considering their widescale applications in catalysis [1] This Poster reports the facile formation of nickel phosphides and rare pure-phase transformations within this system. The decomposition of nickel acetate tetrahydrate (Ni(AC) 2 .4H 2 O) in tri- octylphosphine oxide (TOPO)/tri- n -octylphosphine (TOP) and hexadecylamine (HDA)/TOP at 300 ℃ for 1h resulted in phase-pure Ni 2 P and Ni 5 P 4 materials, respectively in a hot injection route. The thermolysis of Ni(AC) 2 .4H 2 O in the presence of 10% copper acetate monohydrate (Cu(AC) 2 .H 2 O) or 10% manganese acetate (Mn(AC) 2 ) in TOPO/TOP at 300 ℃ for 1h, however, resulted in the phase transformation of Ni 2 P to Ni 5 P 4 . The reverse transformation of Ni 5 P 4 to Ni 2 P particles was obtained from the decomposition of Ni(AC) 2 .4H 2 O with 10% doping of Cu(AC) 2 .H 2 O or Mn(AC) 2 in HDA/TOP via the same colloidal route. The decomposition of Ni(AC) 2 .4H 2 O with 5% doping of Cu(AC) 2 .H 2 O or Mn(AC) 2 in TOPO/TOP or HDA/TOP however yielded a mixture of phases (Ni 2 P/Ni 5 P 4 ). Lattice stress and the size of incorporated dopants as well as the nature of surfactants were found to be pivotal to these rare transformations. The formed phosphides were investigated as electrocatalysts in overall water splitting and supercapacitance reactions. These phase transformations resulted in better catalytic activity and stability as well as reaction kinetics indicating suitability in practical water-splitting technologies. References 1. G. E. Ayom, M. D. Khan, G. B. Shombe, J. Choi, R. K. Gupta, W. E. van Zyl and N. Revaprasadu,Inorg. Chem., 2021,60, 11374–11384
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