Xingzhi Wang

Facile synthesis of core-shell ZnO/Cu2O heterojunction with enhanced visible light-driven photocatalytic performance

AbstractAs p–n heterojunction photocatalysts usually possess dramatically improved photocatalytic activity than single photocatalysts, a novel ZnO/Cu2O heterojunction was designed by a facile self-templating method in this study. The crystal structure, chemical composition, surface morphology, and optical property of ZnO/Cu2O heterojunction were investigated to clarify the structure-property correlation. Scanning electron microscope and transmission electron microscope images proved the uniform core-shell submicrospheres of ZnO/Cu2O, in which a three-dimensional flower-like ZnO core was coated by a shell comprised of Cu2O nanoparticles. The photoresponse result showed that the band gap of the ZnO/Cu2O core-shell submicrospheres became narrow, and the absorption edge shifted from the ultraviolet region (380 nm) to the visible region (500 nm) compared with the pure ZnO microflowers. For the degradation of Rhodamine B under visible light, the photocatalytic efficiency of ZnO/Cu2O submicrospheres reached 96% within 40 min of reaction time, which was 3.8 times higher than that of pure ZnO microflowers and up to 4.5 times than that for pure Cu2O nanoparticles. The remarkable visible light-driven photocatalytic performance is mainly attributed to the extended photoresponse range and effective separation of the photo-generated electron-hole pairs in the unique heterojunction. ZnO/Cu2O core-shell microspheres for the degradation of RhB under visible lightHighlightsA novel core-shell ZnO/Cu2O heterojunction was synthesized by a facile self-templating method.Core-shell ZnO/Cu2O submicrospheres were comprised of three-dimensional flowerlike ZnO core coated by a shell of Cu2O nanoparticles.The band gap of ZnO/Cu2O submicrospheres became narrow and the absorption edge shifted to the visible region.ZnO/Cu2O submicrospheres exhibited better visible light-driven photocatalytic performance than pure ZnO or Cu2O.

Enhanced photoelectrochemical properties of nanocrystalline TiO 2 electrode by surface sensitization with Cu x O quantum dots

Nanoporous anatase TiO2 films were fabricated by a screen-printing method, and CuxO quantum dots (QDs) were deposited on the TiO2 films through successive ionic layer adsorption and reaction (SILAR). The amount of CuxO QDs on the TiO2 films are controlled by changing the number of SILAR cycles. The morphology, microstructure, optical, and photoelectrochemical properties of different CuxO sensitized TiO2 films (CuxO/TiO2) were investigated in detail. The nanoporous TiO2 film offers a large surface area for anchoring QDs. QD deposited samples exhibited a significant improvement in photoelectrochemical performance than the bare of TiO2. CuxO/TiO2, prepared with 7 SILAR cycles, showed the best photoelectrochemical properties, where the photocurrent density was enhanced to 500.01 μA/cm2 compared with 168.88 μA/cm2 of bare TiO2 under visible light. These results indicate that the designed CuxO/TiO2 structure possesses superior charge separation efficiency and photoelectrochemical properties.