Quantitative In Situ Monitoring of Cu-Atom Release by Cu(2)O Nanocatalysts under Photocatalytic CO(2) Reduction Conditions: New Insights into the Photocorrosion Mechanism

Cu(2)O is among the most promising photocatalysts for CO(2) reduction, however its photocorrosion remains a standalone challenge. Herein, we present an in situ study of the release of Cu ions from Cu(2)O nanocatalysts under photocatalytic conditions in the presence of HCO(3) as a catalytic substrate in H(2)O. The Cu-oxide nanomaterials were produced by Flame Spray Pyrolysis (FSP) technology. Using Electron Paramagnetic Resonance (EPR) spectroscopy in tandem with analytical Anodic Stripping Voltammetry (ASV), we monitored in situ the Cu(2+) atom release from the Cu(2)O nanoparticles in comparison with CuO nanoparticles under photocatalytic conditions. Our quantitative, kinetic data show that light has detrimental effect on the photocorrosion of Cu(2)O and ensuing Cu(2+) ion release in the H(2)O solution, up to 15.7% of its mass. EPR reveals that HCO(3) acts as a ligand of the Cu(2+) ions, promoting the liberation of {HCO(3)-Cu} complexes in solution from Cu(2)O, up to 27% of its mass. HCO(3) alone exerted a marginal effect. XRD data show that under prolonged irradiation, part of Cu(2+) ions can reprecipitate on the Cu(2)O surface, creating a passivating CuO layer that stabilizes the Cu(2)O from further photocorrosion. Including isopropanol as a hole scavenger has a drastic effect on the photocorrosion of Cu(2)O nanoparticles and suppresses the release of Cu(2+) ions to the solution. Methodwise, the present data exemplify that EPR and ASV can be useful tools to help quantitatively understand the solid–solution interface photocorrosion phenomena for Cu(2)O.