Microstructural Evaluation and Highly Efficient Photocatalytic Degradation Characteristic of Nanostructured Mg65Ni20Y15-xLax (X=1, 2, 3) Alloys

A series of La and Y rates of Mg65Ni20Y15-xLax (X = 1, 2, 3) alloys was synthesized by mechanical alloying in order to investigate the influence of varying amounts of Y and La on the microstructure and degradation performance of methyl blue. The nano-structured alloys were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive spectrometry (EDX), UV-Vis spectroscopy (UV) and Fourier-Transform Infrared Spectroscopy (FTIR) techniques. Three different intermetallic phases such as Mg24Y5, Mg17La2 and Mg2Ni were obtained after 75 h of milling time. With an increase in the milling time, the particle and crystallite size of the Mg65Ni20Y15-xLax (X = 1, 2, 3) powders were decreased and the crystallite sizes of the alloys were calculated below 20 nm after 75 h of milling time. The composition of the nanostructured powders after mechanical alloying were determined to be very close to the initial composition by EDX analyses. The time and amount-dependent photocatalytic degradation of methyl blue samples were investigated under visible light at room temperature. The photocatalytic degradation properties of methyl blue in the water samples were evaluated by recording the decrease of absorbances at 590 nm in UV-Vis absorption spectra. The nanostructured Mg65Ni20Y15-xLax (X = 1, 2, 3) powders demonstrated highly efficient photocatalytic properties in daylight even in the absence of any oxidant, heat or light source. After a 30 min exposure, the UV-Vis and FT-IR spectra indicated that the methyl blue samples became colourless using Mg65Ni20Y15-xLax (X = 1, 2, 3) type catalysts. Among the alloys, the Mg65Ni20Y13La2 is the best catalyst for the photocatalytic degradation of methyl blue possibly because of it had the smallest crystalline size compared to the other alloys.