Open AccessMorphology‐Controlled Aluminum‐Doped Zinc Oxide Nanofibers for Highly Sensitive NO 2 Sensors with Full Recovery at Room Temperature
Author(s) -
Sanger Amit,
Kang Sung Bum,
Jeong Myeong Hoon,
Im Min Ji,
Choi In Young,
Kim Chan Ul,
Lee Hyungmin,
Kwon Yeong Min,
Baik Jeong Min,
Jang Ho Won,
Choi Kyoung Jin
Publication year - 2018
Publication title -
advanced science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.388
H-Index - 100
ISSN - 2198-3844
DOI - 10.1002/advs.201800816
Subject(s) - nanofiber , materials science , adsorption , electrospinning , polyvinylpyrrolidone , fiber , nanotechnology , chemical engineering , optoelectronics , analytical chemistry (journal) , polymer , composite material , polymer chemistry , chemistry , engineering , organic chemistry , chromatography
Room‐temperature (RT) gas sensitivity of morphology‐controlled free‐standing hollow aluminum‐doped zinc oxide (AZO) nanofibers for NO 2 gas sensors is presented. The free‐standing hollow nanofibers are fabricated using a polyvinylpyrrolidone fiber template electrospun on a copper electrode frame followed by radio‐frequency sputtering of an AZO thin overlayer and heat treatment at 400 °C to burn off the polymer template. The thickness of the AZO layer is controlled by the deposition time. The gas sensor based on the hollow nanofibers demonstrates fully recoverable n‐type RT sensing of low concentrations of NO 2 (0.5 ppm). A gas sensor fabricated with Al 2 O 3 ‐filled AZO nanofibers exhibits no gas sensitivity below 75 °C. The gas sensitivity of a sensor is determined by the density of molecules above the minimum energy for adsorption, collision frequency of gas molecules with the surface, and available adsorption sites. Based on finite‐difference time‐domain simulations, the RT sensitivity of hollow nanofiber sensors is ascribed to the ten times higher collision frequency of NO 2 molecules confined inside the fiber compared to the outer surface, as well as twice the surface area of hollow nanofibers compared to the filled ones. This approach might lead to the realization of RT sensitive gas sensors with 1D nanostructures.