CuO thin films deposited by DC sputtering and their photocatalytic performance under simulated sunlight

CuO thin films were obtained by DC Sputtering varying the deposit time: 10, 20 and 30 min with the thickness of 60, 120 and 180 nm, respectively. These films were used photocatalysts in two different photocatalytic processes: hydrogen production and CO2 photoreduction under simulated sunlight. The film with 120 nm of thickness generated the highest amount of hydrogen (24 mu mol) of the films tested. Furthermore, the ellipsometry results showed that this film absorbs the simulated light in the UV-to-IR region, which facilitates their photocatalytic performance. In the CO2 photoreduction process, the CuO film with the lowest thickness exhibited the best performance, yielding 6816 mu mol/g CH2O, while the film of 120 nm in thickness generated a mixture of CH3OH (1536 mu mol/g) and CH2O (450 mu mol/g). It is assumed that the optical properties, such as absorption coefficient, refractive index, and extinction coefficient, of the film favored the production of formaldehyde and methanol.