Electrochromism of Electrochemically Codeposited Composites of Phosphomolybdic Acid and Tungsten Trioxide

The electrochromism of phosphomolybdic acid (PM) in solution and in a series of solid composites is investigated. PM in solution changes color from light yellow to dark blue upon reduction whereas the composites show a change from light yellow to bluish brown under identical conditions. PM could not be deposited as a thin film by itself, and electrochemical codeposition was used to incorporate it into the matrix. The basic electrochromatic properties of are changed upon the incorporation of PM even in small quantities. The composites have a more intense color, a different color spectrum, and a slower electrochromic response speed than that of . The composites, like , are also degraded by slow and continuous potential cycling.