S-scheme construction boosts highly active self-supporting CeO2/Cu2O photocatalyst for efficient degradation of indoor VOCs

Photocatalyst-governing degradation of VOCs emitted from household products is promising due to its high performance and long-term durability. In this study, unique hierarchical CeO2/Cu2O nanowire arrays with S-scheme construction grow on a Cu mesh through a simple wet chemical method. Abundant oxygen vacancies on CeO2 work as adsorption sites, and the effective separation of photogenerated carriers driven by built-in electric field in the S-scheme CeO2/Cu2O heterojunction generates mobile reactive oxygen radicals for oxidizing target VOCs. Spectra of Kelvin probe force microscopy (KPFM) reveal that the potential difference at the CeO2/Cu2O interface grows from 9 mV in dark to 29 mV under irradiation, demonstrating a powerful force for driving the migration of photoelectrons. Therefore, under simulated sunlight exposure, 50 ppm of toluene, xylene and formaldehyde can be completely degraded in 70, 50 and 6 min by 15 cm2 CeO2/Cu2O mesh, respectively. The elimination of actual indoor VOCs confirms the practicability of the self-supporting CeO2/Cu2O catalyst, which figures out new ideas for designing efficient photocatalysts for the removal of VOCs pollutants.