Electrochemical behaviour of a composite Rh/TiO<inf>2</inf> layer formed potentiodynamically on titanium surface

Abstract

Potentiodynamic polarization of a mechanically polished titanium electrode in a diluted solution of Rhodium(III) chloride in 0.1 M perchloric acid was performed, resulting in simultaneous formation of both Rh and TiO2 films. The morphology of obtained Rh/TiO2 composite film followed the morphology of titanium support, as evidenced by SEM technique. This composite surface was examined by cyclic voltammetry in both acidic and alkaline solutions, in the potential region of both hydrogen and oxygen underpotential deposition. The charge related to hydrogen underpotential deposition corresponded to a surface roughness of 43. As a consequence of high surface roughness, the diffusion current of oxygen reduction in an oxygen saturated 0.1 M NaOH solution, measured by voltammetry on rotating disc electrode, was found to be comparable to the current of hydrogen underpotential deposition.