A High-Efficiency TiO2/ZnO Nano-Film with Surface Oxygen Vacancies for Dye Degradation

Abstract

Photocatalytic degradation of organic pollutants in water is a highly efficient and green approach. However, the low quantum efficiency is an intractable obstacle to lower the photocatalytic efficiency of photocatalysts. Herein, the TiO2/ZnO heterojunction thin films combined with surface oxygen vacancies (OVs) were prepared through magnetron sputtering, which was designed to drive rapid bulk and surface separation of charge carriers. The morphology and structural and compositional properties of films were investigated via different techniques such as SEM, XRD, XPS, Raman, AFM, and XPS. It has been found that by controlling the O2/Ar ratio, the surface morphology, thickness, chemical composition, and crystal structure can be regulated, ultimately enhancing the photocatalytic performance of the TiO2/ZnO heterostructures. In addition, the heterojunction thin film showed improved photocatalytic properties compared with the other nano-films when the outer TiO2 layer was prepared at an O2/Ar ratio of 10:35. It degraded 88.0% of Rhodamine B (RhB) in 90 min and 90.8% of RhB in 120 min. This was attributed to the heterojunction interface and surface OVs, which accelerated the separation of electron–hole (e–h) pairs.

Engineering Schottky-like and heterojunction materials for enhanced photocatalysis performance – a review

“…The fabrication of TiO 2 /ZnO heterojunctions was also explored using magnetron sputtering techniques, 95 which led to a deposition of 350 nm thick ZnO layer followed by a 120–200 nm thick TiO 2 coating (Table 2, entry 8). The thicker coatings of TiO 2 showed the presence of a high fraction of the rutile phase, which provided recombination centres for photo-generated electron and hole pairs, decreasing the separation efficiency and catalytic performance.…”

Synergistic Microbial Inhibition and Quality Preservation for Grapes through High-Voltage Electric Field Cold Plasma and Nano-ZnO Antimicrobial Film Treatment

“…The mechanism of nano-ZnO involves contact, permeation, and oxidation, which affect the microbial cell membranes and internal components, and ultimately render the microbes inactive [25,26]. However, the sterilization effect can be reduced by insufficient ambient light [27], excessive ZnO particle size [28], and the presence of oxygen vacancies [29]. To the best of our knowledge, there has been no report of simultaneously using HVEF-CP and nano-ZnO on grapes or the impact of such co-processing on grape quality.…”

High Refractive Index Silica-Titania Films Fabricated via the Sol–Gel Method and Dip-Coating Technique—Physical and Chemical Characterization

“…Attractive materials for the application in optoelectronics include transition metal oxides films (TMOs) (TiO 2 , ZnO, HfO 2 , ZrO 2 , Ta 2 O 5 ) which, due to high optical energy band gaps, show good transmission properties in the Vis–NIR spectral range [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 ]. The TiO 2 and ZnO films have sensor [ 9 , 10 , 11 , 12 ] and photocatalytic properties [ 13 , 14 ]. In the structures of photovoltaic cells, they are used as buffer films [ 15 ] or as acceptor films, blocking holes and effectively returning electrons to the anode [ 16 , 17 ].…”

“…TMOs are also used in integrated optics technologies [ 22 , 23 , 24 , 25 , 26 , 27 , 28 ]. TMO films can be produced using physical vapor deposition (PVD) methods, including e-beam evaporation [ 2 , 4 ], magnetron sputtering [ 7 , 8 , 9 , 13 , 23 , 29 ], pulse laser deposition PLD [ 30 ], or chemical methods, including chemical spray pyrolysis [ 12 ], atomic layer deposition (ALD) [ 5 , 10 , 14 , 17 ] and the sol–gel method [ 6 , 18 , 20 , 22 , 26 , 28 ]. PVD methods require utilization of specialized technological instruments including vacuum systems.…”