Synthesis and characterization of NiO/TiO2 porous films and their photocurrent-enhanced mechanism in gas phase

•The photocurrent of NiO/TiO2 porous films in methanol is much higher than usual.•A quantitative formula confirms the synergistic effect between the p–n junction and methanol.•A new insight into gas molecule photooxidation on the coupling catalyst is provided.

In this work, the NiO/TiO2 porous films with different weight-ratios were prepared by the screen-printing technique. To uncover the roles of gas molecules and the junction on the carrier migration, the photocurrent measurements in methanol were employed. The corresponding experiments were performed in a high-throughput platform where the concentration of target gas and the applied bias voltage were both precisely controlled. Our results revealed that not only the p–n junction but also methanol had a distinct enhancement effect on the photocurrent. Furthermore, the synergistic effect was further confirmed by a quantitative formula of multi-factor effect (ME) based on the carrier density. In addition, a new insight into gas molecule photooxidation on the coupling catalyst was provided, which was of great significance for potential application to photocatalytic degradation and gas sensing.