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Interface engineering is one of the promising strategies for the long‐term stabilization of perovskite solar cells (PSCs), preventing chemical decomposition induced by external agents and promoting fast charge transfer. Recently, MXenes–2D structured transition metal carbides and nitrides with various functionalization (O, ‐F, ‐OH) have demonstrated high potential for mastering the work function in halide perovskite absorbers and have significantly improved the n‐type charge collection in solar cells. This work demonstrates that MXenes allow for efficient stabilization of PSCs besides improving their performances. A mixed composite bathocuproine:MXene, that is, (BCP:MXene) interlayer, is introduced at the interface between an electron‐transport layer (ETL) and a metal cathode in the p‐i‐n device structure. The investigation demonstrates that the use of BCP:MXene interlayer slightly increases the power conversation efficiency (PCE) for PSCs (from 16.5 for reference to 17.5%) but dramatically improves the out of Glove‐Box stability. Under ISOS‐L‐2 light soaking stress at 63 ± 1.5 °C, the T80 (time needed to reduce efficiency down to 80% of the initial one) period increases from 460 to > 2300 hours (h).

Industrialization is serious for changing the environment and natural water composition, especially near cities and manufacturing areas. Logically, the new ultrasensitive technology for precise control of the quality and quantity of water sources is needed. Herein, an innovative method of polarization fluorescence analysis (FPA) was developed to measure the concentration of heavy metals in water. The approach was successfully applied for precise tests with reduced analysis time and increased measurement efficiency among laboratory methods. Based on this work, the investigations established the new type of carbon quantum dots (CQDs) with controllable fluorescence properties and functionalized amino—groups, which is appropriate for FPA. The parameters of one and two-step microwave synthesis routes are adjusted wavelength and fluorescence intensity of CQDs. Finally, under optimized conditions, the FPA is showed the detection of copper (2+) cations in water samples below European Union standard (2 mg/L). Moreover, in comparison with fluorescence quenching, polarization fluorescence is proved as a convenient, simple, and rapid test method for effective water safety analysis.

Carbon quantum dots (CQDs) are an excellent eco-friendly fluorescence material, ideal for various ecological testing systems. Herein, we establish uniform microwave synthesis of the group of carbon quantum dots with specific functionalization of ethylenediamine, diethylenetriamine, and three types of Trilon (A, B and C) with chelate claws -C-NH3. CQDs’ properties were studied and applied in order to sense metal cations in an aquatic environment. The results provide the determination of the fluorescence quench in dots by pollutant salts, which dissociate into double-charged ions. In particular, the chemical interactions with CQDs’ surface in the Irving–Williams series (IWs) via functionalization of the negatively charged surface were ascribed. CQD-En and CQD-Dien demonstrated linear fluorescence quenching in high metal cation concentrations. Further, the formation of claws from Trilon A, Trilon B, and C effectively caught the copper and nickel cations from the solution due to the complexation on CQDs’ surface. Moreover, CQD-Trilon C presented chelating properties of the surface and detected five cations (Cu2+, Ni2+, Ca2+, Mg2+, Zn2+) from 0.5 mg/mL to 1 × 10−7 mg/mL in the Irving–William’s series. Dependence was mathematically attributed as an equation (ML regression model) based on the constant of complex formation. The reliability of the data was 0.993 for the training database.

Amino- and carboxyl-functionalized carbon quantum dots (Amino-CQDs) were synthesized through fast and simple microwave treatment of a citric acid, ethylenediamine and ethylenediaminetetraacetic acid (EDTA) mix. The reproducible and stable optical properties from newly synthesized CQD dispersion with a maximum absorbance spectra at 330 nm and the symmetric emission maximum at 470 nm made the Amino-CQDs a promising fluorescence material for analytical applications. The highly aminated and chelate moieties on the CQDs was appropriate for a copper (Cu2+) cation sensor in the linear range from 1 × 10−4 mg/mL to 10 mg/mL with a limit of detection at 0.00036 mg/mL by static fluorescence quenching effects. Furthermore, Amino-CQDs demonstrated stable fluorescence parameters for assays in diluted alkali metal solution (Na+ and K+) and sea water. Finally, a visual sensor, based on Amino-CQDs, was successfully created for the 0.01–100 mg/mL range to produce a colorimetric effect that can be registered by computer vision software (Open CV Python).

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Broad application of CuO nanoparticles (CuO-NP) for industrial and household purposes leads to a continuous increase in their discharge to, and, hence, ever-increasing environmental hazards for aquatic ecosystems. Microalgae-based technologies hold promise for bioremediation of diverse hazardous micropollutants (HMP), including NP, from wastewater. In this study, we tested the ability of the green microalga Desmodesmus sp. to accumulate CuO-NP or their components. We also assessed the tolerance of this microalga to the environmentally relevant concentrations of CuO-NP. Using scanning electron microscopy, we demonstrated that the average size of CuO-NP was 50–100 nm, and their purity was confirmed with elemental composition analysis. Tests of the colloidal suspensions of CuO-NP showed that the hydrodynamic diameter of CuO-NP and their aggregates was below 100 nm. Flow cytometry analysis showed that CuO-NP at a concentration of 100 µg L−1 slightly inhibited the viability of microalgae cells and led to an increase in their oxidative stress. The assessment of the condition of photosystem II showed that CuO-NP exert a multifaceted effect on the photosynthetic apparatus of Desmodesmus sp., depending on the concentration of and the exposure to the CuO-NP. Desmodesmus sp. turned to be relatively tolerant to CuO-NP. In addition, the ICP-MS method revealed increased bioaccumulation of copper by microalgae cells in the experimental groups. The outcomes of this study indicate that the Desmodesmus sp. has a significant potential for bioremoval of the copper-based nanostructured HMP from an aquatic environment.

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