Mechanism and Microstructure of Electroless Ni-Fe-P Plating on CNTs

Electroless Ni-Fe-P alloy plating on the surface of CNTs was carried out with a bath using citrate salt and lactic acid as complex agents. We proposed a chemical reaction mechanism. The morphology, structure and chemical composition of the Ni-Fe-P/CNTs were studied with the aid of a scanning electronic microscope (SEM), X-ray diffraction (XRD) and an energy-dispersive X-ray spectral analysis (EDS). The results show that through a correct pre-treatment and electroless plating, Ni-Fe-P/CNTs composite particles can be obtained. The optimum electroless plating parameters of 35–42 °C and pH of 8.5–9.7 were achieved. The as-plated Ni-Fe-P alloy is amorphous. After a heat treatment at 500 °C for 90 min in H2, the coating is transformed into crystalloid Ni3P, Fe2NiP and (Fe, Ni)3P. The Ni-Fe-P alloy coating on the surface of CNTs is smooth and unique. The amount of Ni on the surface (mass fraction) of the Ni-Fe-P/CNTs composite particles is 29.13%, that of Fe 3.19% and that of P 2.28%.