Search

Superior sensitive, selective, and repeatable real-time detection of low concentrations of benzene vapor is vitally important for environmental protection and human health. A benzene vapor sensor using three-dimensional photonic crystals (3-D PCs) based on zeolitic imidazolate framework-8@graphene quantum dots (ZIF-8@GQDs) was proposed. The 3-D PCs were acquired by centrifuging ZIF-8@GQDs pseudo-solutions, which were prepared via hydrothermal methods. The application of the ZIF-8@GQDs 3-D PCs sensor for optical benzene vapor detection via the strong π–π stacking interactions and large specific surface area and abundant open-framework structure of the ZIF-8@GQDs was investigated. The ZIF-8@GQDs 3-D PCs sensor exhibits a more sensitive response to benzene vapor compared with the ZIF-8 3-D PCs sensor. The relationship between the wavelength shift and the benzene vapor concentration was demonstrated to be linear. Additionally, the ZIF-8@GQDs 3-D PCs sensor presents a fast optical response and recovery times of 1 s and 7 s for 200 ppm benzene vapor detection, the benzene vapor detection limit can reach 1 ppm, and the deviation of the reflected wavelength varied within 2 nm after 10 cycles. Moreover, the fabricated ZIF-8@GQDs 3-D PCs sensor exhibited reliability and exceptional thermal and long-time storage stability, demonstrating great potential for practical benzene vapor sensing applications. [ABSTRACT FROM AUTHOR]

Label free detection with high sensitivity, selectivity and reliability is crucial for monitoring carbon tetrachloride (CCl 4) vapor, which is a kind of hazardous vapor to human health even at low concentration. In this work, we synthesized the MIL-101(Cr) through a hydrofluoric acid-free (HF-free) method and proposed a label-free high performance optical refractive index CCl 4 vapor sensor based on MIL-101(Cr)/TiO 2 one-dimensional photonic crystals (1DPC). The application of the MIL-101(Cr)/TiO 2 1DPC in CCl 4 vapor optical detection was investigated due to the excellent selectivity and ultrahigh adsorption capacities of MIL-101(Cr) for CCl 4 vapor. The results illustrate that the MIL-101(Cr)/TiO 2 1DPC vapor sensor shows high sensitivity of 0.11 nm/ppm with a good linear relationship in the concentrations range of 0–100 ppm CCl 4 vapor and great selectivity with the value of selectivity(S) varied from 2.63 to 18 comparing CCl 4 vapor with toluene (C 7 H 8), acetone (C 3 H 6 O), n -hexane (C 6 H 14) and dichloromethane (CH 2 Cl 2) vapor. Meanwhile, the MIL-101(Cr)/TiO 2 1DPC sensor presents a fast optical response and recovery time of 1.2 s and 12.1 s with exceptional repeatability and reliability for 100 ppm CCl 4 vapor detection, which are important for practical applications. [Display omitted] • The nano-particle MIL-101(Cr) is synthesized by a HF-free hydrothermal method. • A novel label-free 1DPC CCl 4 vapor sensor based on MIL-101(Cr)/TiO 2 is proposed. • The sensor shows high sensitivity and selectivity to low concentrations of CCl 4 vapor. • The sensor presents a fast optical response and recovery time with exceptional repeatability and reliability. [ABSTRACT FROM AUTHOR]

In this study, we proposed the one-dimensional (1D) photonic crystals (PCs) chlorobenzene sensor assembled by TiO 2 , UiO-66 and graphene oxide (GO). The originality of the sensor is that the PCs structure alternately assembled by TiO 2 , UiO-66 and GO. The unique structure of the sensor can enhance the selectivity and sensibility of the sensor to chlorobenzene vapors because the mesoporous photonic structure built by UiO-66 nanoparticles and GO sheets can generate the van der Waals force and the π-π stacking interaction. The experiment results also demonstrated the detection limits of chlorobenzene vapors can reach 13 ppm and the distinct reflection spectra red-shift of 17.8 nm within 800 ms when exposed to chlorobenzene vapors stream. And that the refection peak displacement errors of the sensor are within 1.5 nm after repeatedly sensing experiments to chlorobenzene vapors. Moreover, thanks to the excellent stability of UiO-66 and GO, the sensor can maintain original performances after ultrasound and heat treatment. With excellent performances, the 1D PCs sensor can be the promising candidate of high-performance chlorobenzene sensors for environmental quality monitoring. [Display omitted] • The 1D photonic crystals chlorobenzene sensor assembled by TiO 2 , UiO-66 and graphene oxide (GO) was proposed. • The sensor possesses excellent selectivity and sensibility to chlorobenzene vapors. • The detection limits of the sensor to chlorobenzene vapors can be as low as 13 ppm. • The sensor showed a quick response of 800 ms to chlorobenzene vapors. [ABSTRACT FROM AUTHOR]

The proposed ZIF-8@ZnO/TiO 2 1DTDPC gas sensor and it's sensing properties toward CCl 4 vapor. • We proposed the ZIF-8@ZnO/TiO 2 1DTDPC gas sensor for CCl 4 vapor detection. • The comparison between ZIF-8/TiO 2 and ZIF-8@ZnO/TiO 2 1DTDP have been achieved. • The ZIF-8@ZnO/TiO 2 nano-sensor shows better quality and more sensitivity to H 2 O vapor. • The nano-sensor presents an excellent selectivity and sensitivity toward CCl4 vapor. • The sensor's optical response time is about 300 ms. • The nano-sensor exhibits exceptional stability and reversibility. This paper is devoted to an investigation of the carbon tetrachloride (CCl 4) sensing properties of the microporous zeolitic-imidazolate framework-8 (ZIF-8) composite with one-dimensional top-defect photonic crystals(1DTDPC) structure. We propose the ZIF-8@ZnO/TiO 2 1DTDPC gas sensor for the first time derived from ZIF-8 composite (ZIF-8@ZnO) and titanium dioxide (TiO 2) by a spin-coating method. Comparing with the ZIF-8/TiO 2 1DTDPC, the ZIF-8@ZnO/TiO 2 1DTDPC shows the better quality and sensing property with the sensitivity to be 0.008 nm/ppm toward the water (H 2 O) vapor. It is found that the ZIF-8@ZnO/TiO 2 1DTDPC exhibit a highly selective detection toward carbon tetrachloride (CCl 4) vapor during the experiment of the carbon tetrachloride (CCl 4), dichloromethane(CH 2 Cl 2), methanol (CH 3 OH), formaldehyde (HCHO), and water(H 2 O) vapor. The relationship between the maximum reflectance peak's shift of the ZIF-8@ZnO/TiO 2 1DTDPC sensor and the increasing concentration of CCl 4 vapor is investigated to be linear with the sensitivity of 0.05 nm/ppm, and the optical response time is obtained to be ∼300 ms with the concentration of 320 ppm. Moreover, the great reversibility and stability were also demonstrated, which are beneficial for practical applications. [ABSTRACT FROM AUTHOR]

• We proposed an enhanced-performance MOF-801/TiO 2 %RH 1DPC nano-sensor. • The nano-sensor exhibits an excellent linear sensitivity of reflection spectrum. • The resolvable humidity variation of the nano-sensor is less than 0.1%RH. • The sensor's optical response time is less than 100 ms. We proposed an enhanced-performance relative humidity (%RH) nano-sensor based on MOF-801/TiO 2 one-dimensional photonic crystals (1DPC). The maximum reflectance-peak wavelength of it shifted obviously in the range of 20%-90% under varying %RH levels, due to the highly moisture-sensitive MOF-801 film in the 1DPC structure. It was demonstrated that the linear spectrum sensitivity of the MOF-801/TiO 2 %RH 1DPC sensor is exceeding 119 pm/%RH from 20%RH to 90% RH, and the sensitivity of reflection power variations exhibits 1.34 dB/%RH with the resolvable relative humidity variation less than 0.1%RH at 15°C. Meanwhile, the sensor shows a fast optical response time less than 100 ms with exceptional repeatability and reliability, which promises successful measurements of human respiration. Moreover, the sensor performance on the structure of 1DPC is investigated, representing a tradeoff between the sensing sensitivity and response time. [ABSTRACT FROM AUTHOR]