The polyaniline/TiO₂ (PANI/TiO₂) composite photocatalysts were prepared by the in situ chemical oxidation of aniline (An) in the presence of TiO₂ particles. For this purpose, photocatalysts with different amounts of PANI polymer were prepared and analysed. Fourier-transform infrared (FT-IR) spectroscopy and thermogravimetric (TG) analysis indicated successful synthesis of the PANI polymer and its conductivity was also determined. The micrographs of field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) were used to explain the impact of the aniline amount on the aggregation process during the synthesis of the composites. The smallest size of aggregates was obtained for the photocatalysts with 15% of PANI (15PANI/TiO₂) due to the formation of homogenous PANI. The photocatalytic activity of studied PANI/TiO₂ photocatalysts was validated by monitoring the discoloration and mineralization of Reactive Red azo dye (RR45) in wastewater. The 15PANI/TiO₂ sample presented the highest photocatalytic efficiency under ultraviolet A (UVA) irradiation, in comparison to pure TiO₂. This was explained by the formation of uniformly dispersed PANI on the TiO₂ particles, which was responsible for the synergistic PANI-TiO₂ effect.

MXene is a 2D transition metal carbide/nitride with excellent electrical, optical and mechanical properties. At present, most MXenes are prepared from the MAX phase by chemical etching with HF or HCl/LiF. This method is very limited in terms of large-scale production owing to the hazardous and toxic fluoride-containing reagents. There is an urgent need to explore safe and reliable synthetic methods to prepare MXene. In this short communication, we describe the mechanochemical route for preparation of the Ti₃C₂T_x from the Ti₃AlC₂. The prepared MXene has been studied by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet–visible (UV/Vis) spectrophotometry and Fourier-transform infrared spectroscopy. The results reported here have paved the way for new preparation methods for the fluorine-free MXenes.

Hydrogels have been investigated due to their unique properties. These include high water content and biocompatibility. Here, hydrogels with different ratios of poly(2-(dimethylamino)ethylmethacrylate) (PDMAEMA) were grafted onto cellulose (Cel-g-PDMAEMA) by the free radical polymerization method and gamma-ray radiation was applied in order to increase crosslinking and content of PDMAEMA. Gamma irradiation enabled an increase of PDMAEMA content in hydrogels in case of higher ratio of 2-(dimethylamino)ethyl methacrylate in the initial reaction mixture. The swelling of synthesized hydrogels was monitored in dependence of pH (3, 5.5 and 10) during up to 60 days. The swelling increased from 270% to 900%. Testing of antimicrobial activity of selected hydrogel films showed weak inhibitory activity against Escherichia coli, Pseudomonas aeruginosa, and Bacillus subtilis. The results obtained by the cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) indicate that chemically synthesized hydrogels have good characteristics for the supercapacitor application.

Hydrogen (H₂) is considered as an ideal fuel for the future. The photo-electrochemical (PEC) water splitting employing semiconducting materials and induced irradiation, preferably of solar spectrum, presents a viable route for H₂ production. In this work, self-ordered chromium-doped TiO₂ nanotube (CT) was fabricated using in-situ electro-anodization. CT surface modification was then performed by photo-deposition of Pt and Pd particles, producing Pt-CT and Pd-CT catalysts, respectively. Their morphological features, crystallinity, surface composition, and optical absorption have been inspected by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), Raman, and UV–vis absorption spectroscopy. Linear sweep voltammetry, chronoamperometry, and open circuit potential methods have been applied to study PEC activities of Pt-CT and Pd-CT catalysts in a form of electrodes. It was found that Pt-CT and Pd-CT electrodes possess excellent photo-generated electron/hole (e⁻/h⁺) separation and transport properties. The enhanced photocurrent responses of 4 and 3 times more than that of CT are revealed for Pt-CT and Pd-CT, respectively. The activity of as-prepared Pt-CT and Pd-CT catalysts was then tested for H₂ generation. The maximum amount of the evolved H₂ followed decreasing order: 1.08 > 0.65 > 0.26 mL cm⁻² h⁻¹ for Pt-CT, Pd-CT, and CT electrodes, respectively, clearly showing the positive contribution of photo-deposited (nano)particles onto CT surface.

We have synthesized polyaniline/ZnO-based (PANI/ZnO) multiphase composite photocatalysts from acid media by a newly proposed two-step in situ polymerization. The first step of synthesis yielded PANI salt required for the PANI/ZnO synergistic effect. In the second step, the aniline oxidation continued, without ZnO dissolution, and it produced PANI base. Thus, both PANI salt and base phases in the composites were detected by FTIR and UV/Vis, while the presence of both ZnO and PANI polymer was confirmed by XRD. Additionally, XRD also showed Zn₅(OH)₈(NO₃)₂·2H₂O and Zn(SO₄)(H₂O) phases in PANI/ZnO-based multiphase composites. Furthermore, the impact of the synthesis conditions on the morphology of the composites was investigated by FE-SEM. The images displayed that ZnO particles were encapsulated in PANI sheets that were formed by the aniline oligomers. Photocatalytic evaluation of PANI/ZnO-based catalysts (i.e., degradation of Acid Blue 25 dye) was conducted and the obtained results confirmed that all the studied composites experienced the PANI/ZnO synergistic effect. It was observed that the best photocatalytic properties were held by the PANI/ZnO_2 sample due to its optimal particle size.