Electrochemical synthesis of nanocrystalline SrNb2O6 powders and characterization of their photocatalytic property

Nanocrystalline SrNb2O6 powders were successfully prepared by a simple electrochemical method for the first time, and the influences of electrolytic solution ingredients, electrolyte concentration, and applied electric current intensity on electrochemical process and products were systemically studied. It was found that the formation of strontium niobates strongly relied on the basic or acidic condition of electrolytic solution. When Sr(OH)2·8H2O or mixed Sr(OH)2·8H2O with SrCl2·6H2O was used as electrolyte, Sr5Nb4O15 and SrNb2O6 phases could simultaneously form, and the relative ratio of Sr5Nb4O15 phase to SrNb2O6 declined with the increase of SrCl2·6H2O content in electrolytic solution. The higher the basicity of electrolytic solution, the more favored the crystallization and development of Sr5Nb4O15 phase. Only monoclinic phase SrNb2O6 was obtained in neutral SrCl2·6H2O solution or acidic solution of SrCl2·6H2O with adding hydrochloric acid solution, and a lower concentration of SrCl2·6H2O (≤0.50 M) was beneficial to the formation of SrNb2O6 phase and stable anodic sparks could be observed. Moreover, the crystallization and development of the nanocrystalline SrNb2O6 powders seem to be not sensitive to the applied electric current intensity, their similar particle size and morphology ultimately result in the resemblance in UV–vis absorption and photodegradation. They show a slight red shift of light absorption onset and better photocatalytic performance compared with that prepared by the solid-state reaction.