One-pot synthesis and characterization of metal phosphide-doped carbon xerogels

Transition metal phosphide (Fe2P, Co2P and Ni12P5)-doped carbon xerogels were synthesized by a one-pot pyrolysis of the sol–gel polymer of resorcinol and formaldehyde in the presence of metal nitrates and (NH4)2HPO4. Various techniques, including: X-ray diffraction, N2 adsorption–desorption, scanning electron microscopy, transmission electron microscopy and Mössbauer spectra, were employed for characterizing the physico-chemical properties of this kind of phosphide–carbon composites. Comparing with the corresponding metal-doped carbon xerogels, metal phosphides can exert a different influence on the graphitization temperature, textural properties and surface morphology of the resultant carbon xerogels. Investigations on the mechanism of iron phosphide formation indicated that CH4, CO and C acted probably as reducing agents in the carbothermal reduction of metal phosphates. In addition, Mössbauer studies confirmed that this one-pot synthesis method was an excellent way for preparing high purity metal phosphide-doped carbon xerogels.