Dispersed pure phases of MoP and Ni2P nanoparticles supported by carbon were synthesized by carbonization of metal-and phosphorus-containing resins under an inert atmosphere. The solid products and the evolution of gases during the carbonization process were investigated by various techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), N-2 adsorption-desorption analysis, and mass spectrometry (MS). The resins underwent two carbonization stages: the low-temperature carbonization stage (<650 degrees C) and the high-temperature carbonization stage (>= 650 degrees C). There was an initial reduction of Mo and Ni precursors in the low-temperature region. However, the formation of phosphides was observed in the high-temperature carbonization stage, in which Mo(Ni) and POx species were further reacted with the carbonization products (C, H-2 and CH4) to yield Mo(Ni) phosphide. Note that compared with the traditional H-2-temperature-programmed reduction (H-2-TPR) method, this novel synthesis route produced a large amount of COx besides H2O, leading to a lower water vapor pressure. In addition, the residual carbon produced from resin can play a role in bonding of nanoparticle aggregation. Therefore, the better dispersions and higher surface areas of the as-prepared phosphide nanoparticles were attributed to the mitigation of hydrothermal sintering and the intimate contact between phosphide nanoparticles and carbon species.
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