Hydrogen Peroxide Induced Periodical Catalysis on Copper‐Containing Sulfides

Abstract

AbstractThe crystalline and stoichiometrical conditions for sulfides surfaces to produce oscillations during the reduction of hydrogen peroxide have systematically been investigated. Oscillations were observed with Cu5FeS4, CuFeS2, Cu2S, and CuS, however, did not appear with FeS, FeS2, PbS, MoS2, and CdS electrodes. The monovalent Cu+‐ions have therefore to be considered the essential sites for autocatalysis. Oscillations start to occur as soon as through a cathodic polarization the Fermi‐level in the sulfide is sufficiently raised to fill electrons into antibonding 4 s orbitals of Cu+‐surface atoms. The positive charge of Cu+‐ions is then accordingly reduced to make electron transfer from the perhydroxyle radical energetically impossible. It leaves an autocatalytic reaction mechanism involving two neighbouring reactants as the only remaining catalytical reaction possibility. The role of Cu(I)‐oxide which is responsible for the pronounced light dependence of oscillation frequency and amplitude in the oscillation mechanism is further investigated. Investigations suggest that copper ions in sulfide surfaces play an analogous role as redox partners during the catalytic decomposition of hydrogen peroxide as copper ions in solution. The applied electrode potential permits the control of their catalytical reactivity and the energetical adjustment for the range of periodical catalytical behaviour.