Tailoring the morphology and electrocatalytic properties of electrochemically formed Ag/TiO_2 composite deposits on titanium surfaces

摘要

Three different forms of Ag/TiO_2 composite layers, which have whisker, dot- and island-like distribution of silver were obtained on a mechanically polished titanium surface by adjusting the conditions of silver deposition from an aqueous AgNO_3 solution. The deposit morphology was the result of both the program of electrode polarization and the template action of the simultaneously formed TiO_2 layer. The catalytic activity of the composite layers toward the oxygen reduction reaction was studied in aqueous 0.1 M NaOH solutions and found to be a function of both the surface loading of silver and the type of silver distribution within the Ag/TiO_2 composite layers. The reaction path of oxygen reduction on the composite layers was found to be always a 4e~- one, characteristic otherwise of polycrystalline silver electrodes.