Urchin-like NixPy hollow superstructures: mild solvothermal synthesis and enhanced catalytic performance for the reduction of 4-nitrophenol

In this paper, a two-step solution process was designed for the preparation of urchin-like NixPy hollow superstructures with enhanced catalytic performance for the reduction of 4-nitrophenol. Firstly, nickel microspheres were solvothermally fabricated through the reaction between N2H4 center dot H2O and NiCl2 center dot 6H(2)O in glycol at 170 degrees C for 2 h. Then, urchin-like NixPy hollow superstructures were obtained at 160 degrees C for 6 h via an ethanol-water mixed solvothermal route, employing freshly-prepared Ni microspheres and white phosphorus as the reactants. The as-obtained superstructures were characterized by X-ray powder diffraction ( XRD), scanning electron microscopy ( SEM), transmission electron microscopy ( TEM) and energy dispersive X-ray spectrometry ( EDS). The time-dependent shape evolution experiments confirmed that the formation of urchin-like NixPy hollow superstructures was attributed to the Kirkendall effect. Experiments discovered that Ni microspheres, Ni@NixPy core-shell structures and urchin-like NixPy hollow superstructures could be used as catalysts for the reduction of 4-nitrophenol to 4-aminophenol. The order of their catalytic activities was Ni microspheres < Ni@NixPy core-shell structures < urchin-like NixPy hollow superstructures.