Enhanced hydrogen formation during the catalytic decomposition of H2O2 on metal oxide surfaces in the presence of HO radical scavengers

Abstract

Presently and for the foreseeable future, hydrogen peroxide and transition metal oxides are important constituents of energy production processes. In this work, the effect of the presence of HO radical scavengers on the product yield from the decomposition of H₂O₂ on metal oxide surfaces in aqueous solution was examined experimentally. Scavenging the intermediate product HO˙ by means of Tris or TAPS buffer leads to enhanced formation of H₂. In parallel, a decrease in the production of the main gaseous product O₂ is observed. Under these conditions, H₂ formation is a spontaneous process even at room temperature. The yields of both the H₂ and O₂ depend on the concentration of Tris or TAPS in the reaction media. We observed that TAPS has a higher affinity for the surface of ZrO₂ than does Tris. The difference in adsorption of both scavengers is reflected by the difference in their influence on the product yields. The observed sensitivity of the system H₂O₂–ZrO₂ towards the two different scavengers indicates that O₂ and H₂ are formed at different types of surface sites.