Implementing sensitive and fast ppb-level formaldehyde sensing at room temperature is still extremely demanded for practical indoor air quality monitoring. Herein, we developed a visible-light sensitive and dipole modified graphene-based...
Formaldehyde
(HCHO) sensing plays a critical role for indoor environment
monitoring in smart home systems. Inspired by the unique hierarchical
structure of cactus, we have prepared a ZnO/ANS-rGO composite for
room-temperature (RT) HCHO sensing, through assembling hollow cactus-like
ZnO nanorods with 5-aminonaphthalene-1-sulfonic acid (ANS)-modified
graphene nanosheets in a facile and template-free manner. Interestingly,
it was found that the ZnO morphology could be simply tuned from flower
clusters to hollow cactus-like nanostructures, along with the increase
of the reaction time during the assembly process. The ZnO/ANS-rGO-based
sensors exhibited superior RT HCHO-sensing performance with an ultrahigh
response (68%, 5 ppm), good repeatability, long-term stability, and
an outstanding practical limit of detection (LOD: 0.25 ppm) toward
HCHO, which is the lowest practical LOD reported so far. Furthermore,
for the first time, a 30 m3 simulation test cabinet was
adapted to evaluate the practical gas-sensing performance in an indoor
environment. As a result, an instantaneous response of 5% to 0.4 ppm
HCHO was successfully achieved in the simulation test. The corresponding
sensing mechanism was interpreted from two aspects including high
charge transport capability of ANS-rGO and the distinct gas adsorbability
derived from nanostructures, respectively. The combination of a biomimetic
hierarchical structure and supramolecular assembly provides a promising
strategy to design HCHO-sensing materials with high practicability.
Achieving convenient and accurate detection of indoor ppb-level formaldehyde is an urgent requirement to ensure a healthy working and living environment for people. Herein, ultrasmall In 2 O 3 nanorods and supramolecularly functionalized reduced graphene oxide are selected as hybrid components of visible-light-driven (VLD) heterojunctions to fabricate ppb-level formaldehyde (HCHO) gas sensors (named InAG sensors). Under 405 nm visible light illumination, the sensor exhibits an outstanding response toward ppb-level HCHO at room temperature, including the ultralow practical limit of detection (pLOD) of 5 ppb, high response (R a /R g = 2.4, 500 ppb), relatively short response/recovery time (119 s/179 s, 500 ppb), high selectivity, and long-term stability. The ultrasensitive room temperature HCHO-sensing property is derived from visible-lightdriven and large-area heterojunctions between ultrasmall In 2 O 3 nanorods and supramolecularly functionalized graphene nanosheets. The performance of the actual detection toward HCHO is evaluated in a 3 m 3 test chamber, confirming the practicability and reliability of the InAG sensor. This work provides an effective strategy for the development of low-power-consumption ppb-level gas sensors.
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