Developing sensing materials for military explosives and improvised explosive precursors is of great significance to maintaining homeland security. 5-Nitro-1,10-phenanthroline (Aphen)-modified TiO2nanospheres are prepared though coordination interactions, which broaden the absorption band edge of TiO2and shift it to the visible region. A sensor array based on an individual TiO2/Aphen sensor is constructed by regulating the excitation wavelength (365 nm, 450 nm, 550 nm). TiO2/Aphen shows significant response to nitroaromatic explosives since the Aphen capped on the surface of TiO2can chemically recognize and absorb nitroaromatic explosives by the formation of the corresponding Meisenheimer complex. The photocatalytic mechanism is proved to be the primary sensing mechanism after anchoring nitroaromatic explosives to TiO2. The fingerprint patterns obtained by combining kinetics and thermodynamics validated that the single TiO2/Aphen sensor can identify at least six nitroaromatic explosives and improvised explosives within 8 s and the biggest response reaches 80%. Furthermore, the TiO2/Aphen may allow the contactless detection of various explosives, which is of great significance to maintaining homeland security.Keywords:Aphen;TiO2;sensor array;nitroaromatic explosives
For most of the carbon dots (CDs), solid-state fluorescence and room temperature phosphorescence (RTP) are difficult to achieve due to self-quenching and intersystem crossing (ISC) limitations. Here, nitrogen-doped CDs-1 showing both fluorescence and RTP was obtained by hydrothermal reaction from polyvinyl alcohol (PVA) and 5-amino-1,10-phenanthroline (Aphen). The CDs-1 emits blue-green fluorescence in aqueous solution, while emits white fluorescence and yellow-green RTP in the solid state with a RTP lifetime up to 103 ms, exhibiting a long afterglow with a duration of 3 s, which is visible to the naked eyes. The RTP of the CDs-1 is derived from the C N/C N in Aphen and C N/CN in Aphen and C O produced during the carbonization process with a small energy gap between the singlet and triplet states, which helps to realize the ISC. At the same time, the hydrogen bonds between the C N/CN or CO bonds and O H of the not completely carbonized PVA chains on the CDs-1 surface have the advantages of moisture resistance, oxygen barrier and improving the rigidity of CDs-1. Eventually, non-radiative transitions can be suppressed. Based on the decent fluorescence properties, the aqueous solution of CDs-1 can be used to detect TNP and is responsive to pH with a good linear relationship between acid and alkali. In addition, the RTP of CDs-1 can be utilized as banknote anti-counterfeiting material under a long excitation wavelength. This work provides a possibility to realize the multi-mode illumination regulation of CDs by facile one-step strategy.
Purpose The purpose of this paper is to prepare smart coatings with self-healing and self-reporting dual functionalities. Design/methodology/approach Benzotriazole (BTA) and 1,10-phenanthroline-5-amine (APhen) were encapsulated within mesoporous silica nanocontainers (MSN) via one-step method. Then, BTA+APhen@MSN were mixed with epoxy for preparing BTA+APhen@MSN/EP coatings. The microstructure, structure and sustained-release properties of BTA+APhen@MSN nanocontainers were investigated by transmission electron microscopy, Fourier-transform infrared spectroscopy, Brunauer–Emmett–Teller analysis and UV-Vis spectroscopy. The warning performance and corrosion resistance of BTA+APhen@MSN/EP coatings were characterized by optical microscopy and electrochemical impedance spectroscopy. Findings BTA+APhen@MSN exhibit higher corrosion inhibitors loading capacity (31.2 wt.%) and higher corrosion inhibition efficiency (53.07%) than BTA@MSN and APhen@MSN. The BTA+APhen@MSN/EP coatings show excellent self-healing performance. After soaking in 3.5 wt.% NaCl solution for five days, the fitted resistance of scratched coatings increased by 18%. The BTA+APhen@MSN/EP coatings also show superior self-reporting capability, which can provide a warning of coating damage within 30 min by a visible color change. Originality/value The corrosion inhibitors and corrosion warning agent are encapsulated in a nanocontainer to prepare multifunctional nanocomposite. This multifunctional nanocomposite presents a new approach for designing smart coatings with self-healing and self-reporting dual functionalities.
A dual-functional coating was developed by incorporating carbon dots (CDs) based additives with corrosion sensing and inhibition properties into a polyurethane (PU) matrix. The complex formed between CDs and 1,10-Phenanthrolin-5-amine (APhen) displays not only a bright red color but also fluorescence quenching in the presence of Fe (II) and Fe (III) ions produced during steel corrosion . Electrochemical measurement and molecular simulation results demonstrate that compared with the CDs, APhen, and their mixture, CDs-APhen complex with multiple surface functional groups, chemical bonding, parallel adsorption, and higher binding energy with iron surface can offer a good inhibition effect against steel corrosion in 1 M HCl solution. Subsequently, CDs-APhen was anchored onto sericite (SC) structure and then incorporated into PU coating . A PU coating containing 2 wt% CDs-APhen@SC demonstrated good barrier property and self-healing performance, which was ascribed to the corrosion inhibition property of CDs-APhen and the layered structure of SC. In addition, the released CDs-APhen complex provided rapid color/fluorescence responses to Fe ions , offering sensitive self-reporting performance during the initial stage of steel corrosion.
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