The highly reactive and unstable 'white phosphorus', that emits a faint glow when exposed to oxygen, has been used as a single source of 'P', to produce nanoparticles of nickel phosphide. French researchers claim that the highly reactive P atom donor, P4, and a more reactive metal precursor Ni(0) species, combined in a stoichiometric reaction, will revolutionise the preparation of nickel phosphide nanoparticles as there is great potential for large scale reactions. 

Nicolas Mézailles, Pascal Le Floch and colleagues at the Ecole Polytechnique, in Palaiseau, France, have developed this simple route to nanocrystalline nickel phosphides due to the wide range of applications metal phosphides have in catalysis, magnetism and electronics. The traditional procedures to synthesize metal phosphides involve highly toxic phosphorus precursors and require temperatures above 250 ºC. Whilst white phosphorus is highly reactive, it is routinely used in industry on the ton scale. Therefore there would be no need for high temperatures, thus making this method economically viable. 

The motivation behind this work was to 'provide simple access to a whole family of transition-metal phosphides through a low temperature process', said Mézailles. Mézailles believes that the combination of a stoichiometric reaction, low temperatures and the careful choice of ligand, could allow the generation of homogeneous metal phosphide nanoparticles such as InP dots (a very promising semi-conductor material), core-shell structures or metastable phases. Indeed, research in these areas is underway at present. However, 'the underlying challenges are firstly the synthesis and the stabilisation of highly reactive metal(0) nanoparticles with controlled size and dispersity, and secondly the precise study of the insertion of phosphorus in these particles', said Mézailles. 

Michael Brown