Electrochemical Quartz Crystal Microbalance Studies of Electron Addition at Nanocrystalline Tin Oxide/Water and Zinc Oxide/Water Interfaces: Evidence for Band-Edge-Determining Proton Uptake

摘要: Electrochemical quartz crystal microbalance (EQCM) measurements provide compelling evidence for charge-compensating cation uptake by nanocrystalline SnO2 and ZnO electrodes during electron addition. Comparative light water/heavy water establish that the adsorbed or intercalated ions are protons deuterons. Additional studies as a function of pH implicate water, rather than hydronium ions, proton source. The new results, when combined with previous results titanium dioxide in nonaqueous electrolytes, suggest intercalation is general mode reactivity metal oxide semiconductors. Finally, observations raise significant fundamental questions concerning (1) chemical control band energetics, (2) possible band-edge-unpinning phenomena, (3) relationships between edge energies driving forces isolated transfer reactions.