Anion effects on the catalytic decomposition of H2O2 on ZrO2(s) in aqueous systems

Abstract

Various oxide surfaces have been shown to catalyze H2O2 decomposition, resulting in the intermediate formation of hydroxyl and hydroperoxyl radicals. In this work, the impact of bromide, chloride, and perchlorate separately and in combination with bicarbonate on the reaction between H2O2 and ZrO2 was investigated. The reaction was studied by monitoring the concentration of H2O2 as a function of time, and by probing the hydroxyl radical production using tris as a scavenger and monitoring the product formaldehyde. The most significant impact was seen in the presence of Br− and Br−/HCO3−. Br− significantly increases the H2O2 decomposition rate and the yield of formaldehyde, whereas the combination of Br−/HCO3− was shown to decrease the H2O2 decomposition rate as well as the yield of formaldehyde. The increased formaldehyde yield is explained by its formation in reaction with Br2•−. This contrasts the previous assumption that formaldehyde is only formed upon hydrogen abstraction from tris.