The interaction site
of phthalocyanine (Pc) with nitrogen dioxide
(NO
2
) has been characterized using different methods and
found to be conflicting. By knowing the interaction site, the Pc molecule
can be better customized to improve the gas sensitivity. In this article,
the interaction sites of copper phthalocyanine (CuPc) with oxidizing
NO
2
or with reducing gas (ammonia, NH
3
) were
identified using in situ X-ray absorption spectroscopy (XAS). The
sensitivity of CuPc to sub-ppm levels of the tested gases was established
in the CuPc chemoresistive gas sensors. The analyte–sensor
interaction sites were identified and validated by monitoring the
Cu K-edge XAS before and during gas exposure. From the X-ray absorption
near-edge structure and its first derivative, a low or lack of axial
coordination on the Cu metal center of CuPc is evident. Using the
extended X-ray absorption fine structure with molecular orbital information
of the involved molecules, the macrocycle interaction between CuPc
and NO
2
or NH
3
was proposed to be the dominant
sensing mechanism on CuPc sensors.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.