Synthesis and characterization of nickel selenide nanoparticles: Size and shape determining parameters

Nickel selenide nanoparticles of different sizes and shapes were synthesized using a modified solvothermal method. The effects of the reaction time, pH and solvent on the properties of nickel selenide were also explored. The particles synthesized in 1 h yielded mono-dispersed spheres with a Ni _0.95Se phase, whilst the particles synthesized in 3 h resulted in a mixture of spherical and fused cylindrical nanoparticles with a single Ni _0.95Se phase. Further increments of time (6 and 24 h) resulted in mixtures of particle sizes and shapes and both the samples displayed a Ni ₃Se₄ phase. The pH had effected very little changes on the properties of the nanoparticles though at highly acidic pH the particles evolved from spherical shaped Ni_0.95Se to cubic shaped Ni ₃Se₄. The effect of the solvent was also investigated. The water synthesis resulted in mono-dispersed nanospheres with a Ni _0.95Se crystal phase whilst the ethylenediamine synthesized particles resulted in very small particles engulfed in an ethylenediamine layer with a Ni₆Se₅ crystal phase. The particles synthesized in pyridine on the other hand resulted in poly-dispersed Ni₅Se ₅ nanoparticles with spherical and cubic morphologies.