(a) TEM images of Fe2O3–Cu3(HHTP)2-NFs. (b) Gas responses
of the Fe2O3–Cu3(HHTP)2-NFs sensor to 5 ppm
of NO2, HCHO (F), benzene (B), CO (C), acetone (A), H2 (H), ethanol (E), p-xylene (X), toluene
(T), and ammonia (N) under dark conditions and blue light illumination.
(c) Normalized sensing transients of the Fe2O3–Cu3(HHTP)2-NF sensor to 5 ppm of NO2 under different illumination conditions (dark, red, green,
and blue). (d, e) 7 repetitive sensing transients of the Cu3(HHTP)2-NFs and Fe2O3–Cu3(HHTP)2-NFs sensors to 5 ppm of NO2 under
dark conditions and blue light illumination. (f) Response of Fe2O3–Cu3(HHTP)2-NFs
sensors to 0.2–5 ppm of NO2 under blue light illumination
(blue diamond) and to 5 ppm of NO2 under dark conditions.
The error bars in parts b and f were calculated from the gas responses
of three different sensors.