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.

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Herein, perylene imide (PTCDI) is used as a sensitizer to compound with ZnO through solution treatment. Ultraviolet−visible diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy, and Fourier infrared (IR) spectroscopy analysis of the structure and optical properties of the samples shows that the organic semiconductor molecules PTCDI and ZnO have complexes. Analysis of the photoelectric properties of the samples by photocurrent and impedance (EIS) shows that the introduction of PTCDI has a significant inhibitory effect on the recombination of photogenerated electron−hole pairs. Photocatalysis experiments show that under the same conditions, the degradation rates of PTCDI/ZnO composites for methyl orange and methylene blue reach 92% and 99.5%. At the same time, in the photocatalytic removal of the NO test, the PTCDI/ZnO composite material also shows better photocatalytic performance than ZnO. The PTCDI/ZnO composite material can remove 66% of NO within 12 min. This is attributed to the combination of PTCDI and ZnO, which greatly improves the separation efficiency of photogenerated electron−hole pairs, thereby improving the photocatalytic performance of the composite material. It is worth noting that the synthesized PTCDI/ZnO composites not only show excellent photocatalytic performance in solid−liquid systems and gas−solid systems, but also show good photocatalytic stability.