Synthesis of InP nanofibers from tri(m-tolyl)phosphine: an alternative route to metal phosphide nanostructures

The synthesis of InP nanofibers via a new Ullmann-type reaction of indium nanoparticles with tri(m-tolyl)phosphine (P(PhMe)₃) was typically performed to illustrate an alternative route for the preparation of nanostructured metal phosphides, including III–V (13–15) and transition-metal phosphides. Triarlyphosphine compounds such as other two tri(m-tolyl)phosphine isomers, diphenyl(p-tolyl)phosphine, and triphenylphosphine were comparably employed to synthesize InP nanocrystals. From the aspect of the carbonization of triarlyphosphines, Raman spectroscopy and thermo-gravimetric analysis (TGA) investigations of the InP products showed that the stability of these triarlyphosphines conformed to the order of tri(p-tolyl)phosphine ≈ tri(o-tolyl)phosphine < diphenyl(p-tolyl)phosphine < tri(m-tolyl)phosphine < triphenylphosphine. The correlation between the stability of triarlyphosphines and the growth of InP nanocrystals was investigated, and experimental results showed that the relatively stable triarlyphosphines (tri(m-tolyl)phosphine and triphenylphosphine) were favorable for the preparation of one-dimensional (1D) InP nanostructures (nanofibers and nanowires). The reactivity (stability) of triarlyphosphines was also compared with those of P(SiMe₃)₃ (typically see: J. M. Nedeljković, O. I. Mićić, S. P. Ahrenkiel, A. Miedaner and A. J. Nozik, J. Am. Chem. Soc., 2004, 126, 2632) and P(C₈H₁₇)₃ (C. Qian, F. Kim, L. Ma, F. Tsui, P. D. Yang and J. Liu, J. Am. Chem. Soc., 2004, 126, 1195) according to the difference in preparative temperature for phosphide synthesis. Raman and photoluminescence properties of the as-synthesized InP nanocrystals were further studied, and the synthetic mechanism of our method was reasonably investigated by GC-MS analysis. Moreover, the current route was successfully extended to prepare GaP, MnP, CoP and Pd₅P₂ nanocrystals.