COMPARISON OF THE CATALYZED DECOMPOSITION OF HYDROGEN-PEROXIDE OVER SUPERCONDUCTING AND INSULATING BARIUM CUPRATES - KINETICS OF DECOMPOSITION OVER Y2BACUO5

Catalytic activities of two non-conducting cuprates (Ba2Cu3O5, Y2BaCuO 5) and a superconducting cuprate YBa2Cu3O7-delta, prepared by two diff erent methods, were compared using H2O2, solution. The two non-conduct ing barium cuprates were found to be about two orders of magnitude mor e active than the superconducting perovskite-like YBa2Cu3O7-delta. The near coincidence of the kinetic curves for the catalysed decompositio n of H2O2, over YBa2Cu3O7-delta, prepared either from the perovskite-l ike Ba2Cu3O5 and Y2O3 or from its components, proves that Ba2Cu3O5 is essential in the formation of YBa2Cu3O7-delta. First-order kinetics we re observed for the catalysed decomposition of H2O2 solution over the non-perovskite Y2BaCuO5 at the initial stages of the reaction, similar to that of the superconducting perovskite catalyst. A tentative schem e of the possible catalytic reactions for the decomposition of H2O2 so lution over the insulator Y2BaCuO5 is given.