The Oxygen Vacancy Defect of ZnO/NiO Nanomaterials Improves Photocatalytic Performance and Ammonia Sensing Performance

Abstract

In this paper, ZnO/NiO composites rich in oxygen vacancies are prepared by the solvothermal method and reduction method. In the test, through the use of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscope (TEM), diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), and electron paramagnetic resonance (EPR), we effectively prove the existence of phase, morphology and oxygen vacancies in the material. Through the photocatalysis test and gas sensitivity test, it is found that 10% Ni doped OZN-10 has the best photocatalytic activity and gas sensitivity characteristics. The degradation rate of methylene blue (MB) was 98%. The gas sensitivity test shows that OZN-10 has good selectivity, good response performance (3000 ppm, 27,887%) and excellent response recovery time (response time: 50 s, recovery time: 5–7 s) for saturated NH3 gas at standard atmospheric pressure (101.325 KPa) and room temperature (25 °C). The synergistic effect of oxygen vacancy as the center of a trap and p–n heterojunction forming an electric potential field at the interface is explained, and the mechanism of improving photocatalysis and gas sensitivity is analyzed. This work will provide an innovative vision for dual-performance oxygen vacancy modification of heterojunctions through photocatalysis.

Synthesis and characterization of a new phenothiazine-based sensitizer/co-sensitizer for efficient dye-sensitized solar cell performance using a gel polymer electrolyte and Ni–TiO2as a photoanode

“…This charge separation also makes it easier for dyes to expel electrons into the TiO 2 conduction band, indicating that POBA dye is suitable for DSSC applications. 98,99 This observation confirms the effective doping of Ni into the TiO 2 . In addition, the test results also show that Ni doping helps to suppress the transformation of TiO 2 from anatase to rutile (the same result as that of XRD).…”

“…95–97 On the other hand, interplanar spacings of about d = 0.35 nm and d = 0.20 nm were exhibited by 4% Ni–TiO 2 particles, which are attributed to the (101) plane of anatase TiO 2 and (200) plane of NiO. 98,99 This observation confirms the effective doping of Ni into the TiO 2 . In addition, the test results also show that Ni doping helps to suppress the transformation of TiO 2 from anatase to rutile (the same result as that of XRD).…”

Bifunctional NiCuOx photoelectrodes to promote pseudocapacitive charge storage by in situ photocharging

“…High-resolution TEM (HR-TEM) results were also collected to obtain the lattice information of this material. The lattice distances of 0.237 and 0.205 nm can be attributed to CuO (111) 38 and NiO (200), 39 respectively, probably forming a NiO–CuO heterojunction in the nanosheets (Fig. 2d).…”

NiO-Based Gas Sensors for Ethanol Detection: Recent Progress

“…An EDL is then formed in the hetero area and strongly inhibits the conduction channel. When the heterojunction contacts the target gas, electron release greatly reduces the potential barrier at the heterojunction, causing a bigger change in resistivity and a higher sensitivity [46,98,99].…”