Layer-by-Layer Electrodeposition of FTO/TiO₂/Cu_xO/CeO₂ (1 < x < 2) Photocatalysts with High Peroxidase-Like Activity by Greatly Enhanced Singlet Oxygen Generation

Inorganic nanomaterials have attracted much attention as enzyme mimics because of simple and stable spatial conformation of those artificially synthesized nanocatalysts. Cu₂O, as an important kind of narrow band gap semiconductor, is identified as effective as visible-light-driven photocatalysts, which can catalyze decomposition of H₂O₂ into reactive oxygen species. Moreover, after forming Cu_xO/CeO₂ hybrids, the strongly coupled interface between the two components will further improve their catalytic performance. In this paper, the authors try to construct FTO/TiO₂/Cu_xO/CeO₂ (1 < x < 2) nanohybrids with such a kind of active interface via a layer-by-layer electrodeposition strategy by aid of the following surface etching process. It is found that FTO/TiO₂/Cu_xO/CeO₂ exhibits good peroxidase mimic activity in the dark but much better performance under visible light irradiation (λ ≥ 420 nm) during catalytic oxidation of 3,3′,5,5′-tetramethylbenzidine substrates in the presence of H₂O₂. Detailed characterizations disclose that the construction of TiO₂/Cu₂O pn-heterojunctions do effectively accelerate separation of photogenerated carriers, and the formation of a highly active Cu_xO/CeO₂ interface is synergistically favorable for selectively generating singlet oxygen to boost the catalytic performance of FTO/TiO₂/Cu_xO/CeO₂.