Design of Ag2O/In2O3 heterostructure composites with hollow fish basket-like structures for detecting petroleum volatile gases

Abstract

In this study, Ag2O/In2O3 composites with hollow fish basket-like structure were synthesized by facile one-step hydrothermal method involving the modification of In2O3 by doping with Ag2O, which effectively enhanced the performance of gas-sensitive materials. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) were used to analyze the structure, morphology, and content of the samples. The results showed that the synthesized product was polycrystalline with hollow fish basket-like microsphere structure; moreover, XRD and TEM results demonstrated the formation of p–n heterojunction structure between Ag2O and In2O3. Based on this, the gas-sensitive performance study of Ag2O/In2O3 composites for C3H8-based petroleum volatile gases was carried out by static experimental methods, including the study of operating temperature, humidity, sensitivity response, response-recovery time, selectivity, and stability. The results showed that the composite exhibited the best sensing performance when the Ag2O doping was 0.6%. The maximum sensitivity was obtained for C3H8 at an operating temperature of 140 °C, with a response value of 210.3. This value is roughly 2.52 times greater than the sensitivity of undoped In2O3 (84.1 at 180 °C). Moreover, Ag2O/In2O3 composites exhibited high reaction sensitivity, good selectivity, and excellent stability when the doping amount of Ag2O was 0.6%. The experimental results clearly indicate that adding Ag2O improves the gas-sensitive performance compared to pure In2O3. This is attributed to presence of more adsorbed oxygen and oxygen vacancies on the surface of In2O3, the catalytic effect of Ag2O, and the formation of p–n type heterojunctions.