PRODUCTS AND NUCLEATION ANALYSIS OF PHOTOELECTROCHEMICAL REDUCTION OF CUPRIC IONS IN THE CUSO4-METHANOL-TIO2 SUSPENSION SYSTEM

Photoelectrochemical reduction of cupric ions in the CuSO4-MeOH-TiO2 system was investigated. The characteristics of the deposit were studied by product dissolution analysis. Reaction with nitrous oxide, electron spectroscopy for chemical analysis and Auger chemical shift analysis were used to determine the composition of the product surface, while the bulk deposit, the major product, was identified by X-ray diffraction. It was found that the product was cuprous oxide in the beginning and then turned to metallic copper on successive reaction. Reaction products are controlled by the thermodynamics and mass transfer of the proton which is the product of methanol oxidation. Nucleation of the photoelectrochemical product was further studied by transmission electron microscopy and scanning electron microscopy. The initial nucleation was found to be affected by the back dissolution reaction, and the successive nucleation by the agglomeration of TiO2 particles.