Synthesis and photocatalytic properties of new ternary Ni-Fe-Cr hydrotalcite-like compounds

Ternary Ni-Fe-Cr hydrotalcite-like compounds (NiFeCr-HTLcs) with different Fe3+/Cr3+ mole ratios were synthesized through coprecipitation method. The materials obtained from different synthesis conditions were characterized by powder X-ray diffraction (XRD). The results indicated that the Ni-Fe-Cr hydrotalcite-like compounds can be synthesized through metal coprecipitation when the pH value was in the range of 7.5-11.0 and the molar ratio of M2+/M3+ was in the range of 2-4. After calcining at 600 degrees C, the NiFeCr-HTLcs were converted to Ni-Fe-Cr complex metal oxides. The calcined samples showed higher photocatalytic activity than the NiFeCr-HTLcs precursors and their photocatalytic activity increased as the content of Cr rose in the Cr3+/Fe3+ molar ratio range of 0.05-2. The calcined materials which had a Cr3+/Fe3+ molar ratio of 2 possessed the best photocatalytic activity with 85% degradation of methylene blue (MB) dye under visible light irradiation. For the above composition, possible photocatalytic mechanisms are discussed. Moreover, this ternary complex metal oxide system exhibited satisfactory reusability after four cycles. The facile synthesis process, higher photocatalytic activity under visible light irradiation and satisfactory re-usability enable this complex metal oxide material to be a promising candidate for environmental remediation using visible light. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.