Formaldehyde has been regarded as a common indoor pollutant and does great harm to human health, which has caused the relevant departments to pay attention to its accurate detection. At present, spectrophotometry, gas chromatography, liquid chromatography, and other methods have been proposed for formaldehyde detection. Among them, the gas sensor is especially suitable for common gaseous formaldehyde detection with the fastest response speed and the highest sensitivity. Compared with the formaldehyde sensors based on small molecules, the polymer-based sensor has higher selectivity but lower sensitivity because the polymer-based sensor can realize the specific detection of formaldehyde through a specific chemical reaction. Polymer-related formaldehyde sensors can be very versatile. They can be fabricated with a single polymer, molecularly imprinted polymers (MIP), polymer/metal-oxide composites, different polymers, polymer/biomass material composites, polymer/carbon material composites, and polymer composites with other materials. Almost all of these sensors can detect formaldehyde at ppb levels under laboratory conditions. Moreover, almost all polymer nanocomposite sensors have better sensitivity than single polymer sensors. However, the sensing performance of the sensor will be greatly reduced in a humid environment due to the sensitive coating on the gaseous formaldehyde sensor, which is mostly a hydrophilic polymer. At present, researchers are trying to improve the sensitive material or use humidity compensation methods to optimize the gaseous formaldehyde sensor. The improvement of the practical performance of formaldehyde sensors has great significance for improving indoor living environments.
Indoor gaseous formaldehyde is the main environmental
pollutant
that can cause fatal threats to human health. A number of physical
and chemical methods have been developed to tackle this issue. However,
the existing methods are still unsatisfactory to meet the requirement
of sustainable development owing to the flaws of low efficiency and
reversible or second pollution. Herein, a chemical method based on
a nucleophilic reaction between hydrazine and aldehyde that generates
the only by-product of H2O is designed for the removal
of formaldehyde. 1-Pyrenebutyric hydrazide was synthesized by a simple
esterification reaction and then self-assembled on reduced graphene
oxide (rGO) with a large surface area by forming π–π
stacking to obtain a composite for chemical removal of gaseous formaldehyde
under ambient conditions. In a practical test, the formaldehyde removal
rate could reach 91% of the theoretical value, which meets the requirement
for commercial formaldehyde removal applications. After 10 times recycling,
the formaldehyde removal rate still remains as high as 85%. Moreover,
the composite could be regenerated in weak acidic media, which greatly
reduce the manufacturing cost in practical applications.
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