Enhanced gas sensing performance based on p-NiS/n-In2O3 heterojunction nanocomposites

Heterostructured semiconductor materials, combining the collective advantages of individuals and synergistic properties, have spurred great interest as a new paradigm toward detecting of volatile organic compounds recently. Direct use of NiS as a sensing material is impractical because the structure of NiS is unstable, exhibiting an undesirable sensing performance. Herein, we firstly report its incorporation into an ethanol gas sensor with a conventional n -type sensitive material of In 2 O 3 , and the gas sensing performance of the NiS@In 2 O 3 nanocomposites has been significantly enhanced. Nanofiber-like NiS and In 2 O 3 were fabricated via a synergetic approach of electrospinning and calcination processes. The diameters of crystalline NiS and In 2 O 3 are about 150 nm and 120 nm, respectively. Then, the NiS@In 2 O 3 nanocomposites were prepared via re-calcination of as-prepared NiS and In 2 O 3 nanofibers. The results show that the sensor based on NiS@In 2 O 3 exhibits a detecting limit of as low as 5 ppm and a short response time of 8 s at the optimum temperature of 300 ºC, which outstripped that (13 s) of pristine In 2 O 3 and pure NiS sensors (21 s) for the detection of ethanol gas. The remarkable improvement of sensing performance can be attributed to the p - n heterojunction in multi-component phases of NiS and In 2 O 3 .