aeWe report a simple synthetic route to fabricate crystalline ZnO and CeO 2 /ZnO nanofibrous mats and their sensing characteristics against volatile organic compounds (VOCs) such as benzene, propanol, ethanol, and dichloromethane. Precursor fibers were fabricated by electrospinning of poly(vinyl alcohol) and metal salt(s) at 2.5 kV cm À1 in aqueous solution. The fibers were directly deposited on the crystal surface of a quartz crystal microbalance (QCM). The crystal, which was coated by nanostructured PVA/metal precursor(s) fibers, was subjected to calcination in air at 500 1C for 5 h. The formation of an oxide based nanofiber mat was revealed by scanning electron microscopy and X-ray diffraction. Upon exposure of the nanofiber mats to the VOCs, the compounds adsorbed onto the surface of oxidic fibers. The physisorption of the compounds was confirmed by FTIR and QCM. Both systems showed sensitivity to the VOCs and they hold a broad promise particularly for sensing applications of volatile alcoholic compounds. The introduction of CeO 2 into the ZnO structure reduced the sensitivity of ZnO most probably due to the decrement of oxygen vacancies.
This study focuses on the characterization and optimization of calixarene modified carbon nanotube thin films for gas detection. Calixarene molecules were synthesized individually by considering their functional groups to attract the gas. Calixarene modified carbon nanotube based sensors were fabricated using drop-casting method on a quartz crystal microbalance gold electrode. Carbon monoxide, carbondioxide, oxygen and dry air were used as active gases for adsorption process, while high-purity nitrogen gas was used for desorption process. The selectivity and sensitivity of calixarene modified carbon nanotube are investigated in detail. Our experimental results show that functional calixarene modified carbon nanotube coated quartz crystal microbalance sensors are very sensitive and selective to gas of CO 2 at room temperature operation.
a b s t r a c tThe article describes the synthesis of the new ferrocene-substituted calix [4]arene derivative 4 as sensitive layer, and suggests that the immobilization of it is on a quartz crystal microbalance gold electrode via the drop-casting method in order to produce the calix[4]arene-based QCM sensor. In addition, sensor response of the calix[4]arene-based QCM sensor was investigated towards carbon dioxide (CO 2 ) and carbon monoxide (CO). The sensing and selectivity studies show that the ferrocene-substituted calix [4] arene-based QCM sensor is an effective gas sensor toward both carbon dioxide and carbon monoxide.
Perovskite solar cell (PSC) can be regarded as a continuation of dye sensitized solar cell (DSSC) in terms of the sensitization phenomena that occurred in the functioning molecules. In 2012, a breakthrough propose has been made for the sensitization of PSCs, in which a solid-state structure is offered as an equivalent sensitizer used in DSSC. The power conversion efficiency (PCE) of those solid-state cells reached about twofold of its initial value during the past several years. Immediately after, the researchers followed this propose worldwide. They have introduced an improved efficiency of as much as 20%, which was originally started from its initial value of 4%, just in 4 years. Thus, the new concept, solid perovskite molecules, has eliminated the need for the liquid electrolyte in DSSC while still carrying the advantages of organic solar cells (OSCs). Therefore, the distinctive material of PSC-the organometallic halide molecules (also known as OMH or organic-inorganic trihalides)-inclined an unexpected reputation for solar cell (SC) researches. Hence, it seems that we will witness a new age for solar conversion devices depending on the recent hopeful progresses on PSCs. The high rate of photovoltaic (PV) conversion capacity in PSC is generally expressed by the basic properties possessed by the organic-inorganic perovskite crystal, such as better optical properties and well diffused charges along huge distances during the charge transport.
We present a feasible methodology to prepare nonwetting surfaces from natural minerals. Various ranges of silanes were used for the surface grafting, and the best customization was achieved by monochlorosilane. Water affinity analysis of surface functionalized diatomaceous earth was the key aspect of loading tunable wettability on the particle surface. Covalent attachment was confirmed via X-ray photoelectron spectroscopy (XPS), while thermogravimetric analysis, nitrogen adsorption isotherms, and contact angle measurements were used for the evaluation of grafting density and other fundamental features of hydrophobic particles. Diatomaceous earth was chosen as a prototype to develop an efficient strategy for surface modification which can be apposite to another natural particle, the so-called talc, which represents dichotomic performance to water. The present study paves the way for a new approach that can be employed to any proper inherent texture for the production of superhydrophobic powders.
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