Alexandru Ioan Cuza University

We reported on the sequential development of a high-operative photocatalyst with penta-component inorganic bulk heterojunction for improved charge trapping characteristics at particle-particle interfaces for enhanced solar light-driven photocatalytic degradation of active tetracycline antibiotic. Structural, morphol., optical, and electronic properties of the synthesized samples were investigated using a series of complementary characterization techniques, such as XRD, FE-SEM, HR-TEM, XPS, as well as hard and soft XAS in both total electron yield (TEY) and fluorescence yield (TFY). For the case of the carbon composite material, SrTiO₃@NiFe₂O₄@Fe⁰@Ni⁰@CNTs, a reduced crystallinity when compared to the starting support material was noticed, although this translated into a significant improvement of the morphol. and the photocatalytic performance. The SrTiO₃@NiFe₂O₄@Fe⁰@Ni⁰@CNTs fibrous photocatalyst can efficiently achieve a high-to-total degradation of tetracycline antibiotic under visible light irradiation in less than two hours, following a non-linear PFO kinetic model with an apparent reaction rate of about 0.0606 min^-1 and an 98% photodegradation activity. The XPS and XAS anal. demonstrated unequivocally the appearance of nanoscale zero-valent iron (Fe⁰) and zero-valent nickel (Ni⁰) on the photocatalyst surface, which facilitates the separation of photogenerated e⁺ and h⁺ pairs, and the appearance of more active sites.

Extensive attention and considerable efforts have been made to construct efficient heterogeneous nanoparticulate systems for surface chem. reactions to be active in solar light-driven photodegradation This work addresses current deficiencies of the nanoparticles-focused systems intended for visible light photodegradation by developing a newly-formulated innovative chem.-engineered multi-component system that functions as a recyclabe, nontoxic, active and inexpensive catalyst for photodegradation of tetracyclne antibiotic. Here, we show a straightforward FeOOH nanografting of Al-based SrTiO₃ perovskite material as core-shell nanoflower-like heteronanostructure with enhanced solar light-driven photodegradation capability over harmful antibiotics. A persuasive surface formation mechanism is proposed based on systematic investigation of the assembly process. In-depth caracterization of structural, optical and morphol. properties of the prepared samples was investigated using a series of complementary anal. techniques, such as XRD, FE-SEM, HR-TEM, synchrotron XPS, as well as hard and soft XAS in both total electron yield (TEY) and fluorescence yield (TFY). The oxygen-deficient nature of core and shell interface indicates its n-doping and the availability of free charges in core which can be either transferred to the shell or create localized absorption levels into the valence band. This study provides a real opportunity to rationally photocatalysts design with very promising performance in water treatment.

In this paper, we discuss in the framework of a mechanoelastic model the electronic and mech. behavior of a single layer of spin crossover mols. self-organized on a substrate. We consider the mols. situated in a face-centered-cubic structure interacting in between and with sites in the substrate by the way of connecting springs with given elastic constants The main exptl. results are reproduced, i.e., typical thermal transitions with their incompleteness of the hysteresis loop, residual fractions after low-temperature relaxations, cooperativity, or kinetic features. However, we prove that the simple model, implying fixed neighbors on the substrate for every spin crossover mol., leads in some cases to unphys. situations, corresponding to unexpected large curvatures of the spin crossover layer. Therefore, to go further, we allow every spin crossover mol. to change its adsorption site on the substrate at every moment, by connecting to the closest mols. on the substrate. This approach, corroborated with the use of different densities of the sites on the substrate, allows us to simulate further exptl. observations, such as the appearance of cracks inside the layer or periodic arrangements of apparent heights of spin crossover mols. on the layer leading to moiré patterns, for which exptl. data are also provided.