Construction of Li0.5La0.5TiO3 (LLTO)-In2O3 n-n step scheme heterostructure nanorods for drastically heightening the sensing behavior in H2S gas

Abstract

Owing to the high risk of hydrogen sulfide (H2S) gas, detecting and measuring it in real-time is desired in many fields. In this work, we reported the preparation of the unique lanthanum lithium titanate (Li0.5La0.5TiO3) –In2O3 nanorods and applied them as H2S sensors. The results show that the LLTO-In2O3 heterostructure composite sensors exhibit excellent sensing performance for H2S. The LLTO-In2O3 sensors offer good n-type responses to H2S in a wide range of temperatures (50–400 °C). At the optimum operating temperature (160 °C), the maximum gas-sensitive response of the 1:1 LLTO-In2O3 composite sensor to 50 ppm H2S reaches 116.61, which is 28.51 times larger than that of the original LLTO sensor. The formation of n-n heterojunction structure between LLTO and In2O3 has synergistic effects on strengthening the gas sensitivity of the material. A considerable potential barrier formed at the LLTO-In2O3 heterojunction. An enormous resistance of the nanorods and a further excellent gas-sensitive response are achieved. Meanwhile, the oxygen vacancy (OV) concentration and oxygen reduction performance of the LLTO-In2O3 heterostructure is increased, and the energy band gap is reduced, further promoting the chemical adsorption of O2 and the formation of O− and O2− anions.