Cyclic voltammetry of polyethylene stabilized hydrogen molybdenum bronzes

Abstract

Powder samples of hydrogen molybdenum bronzes (H x MoO 3) were effectively stabilized by the addition of 30 mass% polyethylene powder, pressing and a following thermal treatment. The composite material does not degrade in 0.05 mol l 1 H 2SO 4, so that cyclic voltammetry could be carried out in 0.05 moll 1 H 2SO 4 to give reproducible waves and peak potentials. Extrapolation to the scan rate ν = 0 yields the following redox potentials (all versus the SHE): + 277 mV for phase II in its maximum reduction degree ( x max), + 67 mV for phase III ( x min), -91 0mV for phase III ( xx), -204mV for phase IV and -358 0mV for hydrogen at phase IV. In 0.5 mol l 1 H 2SO 4 the bronze is partially soluble, which leads to a strong decrease of the electrochemical activity.