Investigation of photocatalytic behavior of l-aspartic acid stabilized Zn(1−x)MnxS solid solutions on methylene blue

•Synthesis of l-aspartic acid passivated Zn(1−x)MnxS solid solutions is reported for the first time.•Presence of hydrophilic surface on catalyst enhances the possibility of dye adsorption and photocatalytic activity of catalyst.•Study of dopant concentration on photocatalytic activity of Zn(1−x)MnxS solid solutions.

Water dispersible Zn(1−x)MnxS solid solution photocatalysts stabilized with l-aspartic acid were synthesized by coprecipitation. Their photocatalytic activity was evaluated using methylene blue as a model pollutant. X-ray diffraction and Raman spectroscopy indicated the catalysts had a cubic crystal structure. The gradual increase in zinc sulphide (ZnS) lattice constant with increasing Mn2+ dopant concentration was due to the high ionic radius of Mn2+. Raman spectra exhibited two peaks at 260 and 345 cm−1. Ultraviolet–visible absorption spectra of the catalysts exhibited a strong excitonic peak at 270 nm, which was blue shifted compared with that of bulk ZnS (340 nm). This was attributed to quantum confinement and coupling effects. The hydrophilic l-aspartic acid on the photocatalyst surface had a positive effect on photocatalytic activity. The effects of dye and dopant concentrations on photocatalytic activity were investigated.

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