Controllable synthesis of heterostructured CuO–NiO nanotubes and their synergistic effect for glycol gas sensing

The rapid development of p-type metal oxide semiconductors-based gas sensors for detecting glycol has recently attracted extensive attentions due to its huge hazard to human health. However, the poor sensitivity of the p-type gas sensor constraints its further application. In this work, novel p–p heterojunction CuO–NiO nanotubes have been controllably synthesized for high performance glycol gas sensors through one-pot synthesis approach combined with certain calcination treatment. In order to optimize element ratio of Cu to Ni for high performance gas sensors, the feeding ratio of Cu²⁺/Ni²⁺ in the synthesis process has been systematically studied. As a consequence, the gas sensor based on optimal hybrid nanotubes (CuO–NiO(13:7)) shows the highest sensitivity toward 100 ppm glycol at 110 °C with response/recovery time of 15 and 45 s. This hybrid sensor also shows excellent repeatability and long-term stability. The enhanced sensing properties to glycol are mainly attributed to the synergistic effects of CuO–NiO heterostructure and massively produced oxygen vacancies under the optimized element ratio of Cu to Ni. This work demonstrates the novel heterostructured CuO–NiO nanotubes have great potential for high performance gas sensor.