In this work the preparation of polyamide 12 (PA12) based composites reinforced with pristine and surface-modified carbon nanotubes is reported. A qualitative and quantitative evaluation of multi-walled carbon nanotube functionalization with oxygen containing reactive groups achieved by different procedures of chemical treatment is presented. Simple strong oxidative acid treatment as well as chlorination with subsequent chloroacetic acid treatment were applied. Carbon nanotubes (CNTs) were also subjected to chlorine and ammonia in gaseous atmosphere with small differences in after-ammonia treatment. Commercial COOH-functionalized carbon nanotubes were compared with nanotubes that were laboratory modified. The effect of CNT functionalization was evaluated basing on the improvement of mechanical and thermal properties of polyamide 12 composites prepared by in situ polymerization. It was found that high concentration of oxygen-containing functional groups on nanotube surface is not sufficient to improve the composite performance if the structure of carbon nanotubes is defective. Indeed, the best effects were achieved for composites containing nanotubes modified under mild conditions, seemingly due to a compromise between morphology and surface chemical structure.

Zinc chloride and potassium oxalate are often applied as activating agents for carbon materials. In this work, we present the preparation of ZnO/carbon spheres composites using resorcinol-formaldehyde resin as a carbon source in a solvothermal reactor heated with microwaves. Zinc chloride as a zinc oxide source and potassium oxalate as an activating agent were applied. The effect of their addition and preparation conditions on the adsorption properties towards carbon dioxide at 0 °C and 25 °C were investigated. Additionally, for all tested sorbents, the CO₂ sorption tests at 40 °C, carried out utilizing a thermobalance, confirmed the trend of sorption capacity measured at 0 and 25 °C. Furthermore, the sample activated using potassium oxalate and modified using zinc chloride (a carbon-to-zinc ratio equal to 10:1) displayed not only a high CO₂ adsorption capacity (2.69 mmol CO₂/g at 40 °C) but also exhibited a stable performance during the consecutive multicycle adsorption–desorption process.

In the face of increasing global carbon dioxide emissions and the urgent need to mitigate climate change, the development of efficient and sustainable strategies for CO₂ conversion has gained significant attention. One of the methods of eliminating the harmful effects of CO₂ is its photoreduction. In this paper, ZnO was used as an effective photocatalyst for the photoreduction of CO₂ in a gas-phase system. The influence of particle size on the process efficiency was investigated. The ZnO materials applied in the studies were characterized using XRD, SEM, and low-temperature nitrogen adsorption (BET) methods. The pore volume distribution was calculated based on the DFT method. The investigation confirmed that it had a significant impact on the formation of the product of photocatalysis carbon dioxide. The main identified product was carbon monoxide. Hydrogen and methane were detected as well. Based on the results, it was found that the process efficiency was enhanced with decreasing ZnO particle size, and the most effective catalyst for the photoreduction of CO₂ was the ZnO sample with the smallest particle size (18 nm).

In this paper, a chlorination method is proposed for simultaneous purification and functionalization of carbon nanotubes, thus increasing their ability to use. Carbon nanotubes were obtained by CVD method through ethylene decomposition on the nanocrystalline iron or cobalt or bimetallic iron‐cobalt catalysts. The effects of temperature (50, 250, and 450°C) in the case of carbon nanotubes obtained on the Fe‐Co catalyst and type of catalyst (Fe, Co, Fe/Co) on the effectiveness of the treatment and functionalization were tested. The phase composition of the samples was determined using the X‐ray diffraction method. The quantitative analysis of metal impurity content was validated by means of the thermogravimetric analysis. Using X‐ray Photoelectron Spectroscopy (XPS), Energy Dispersive Spectroscopy (EDS) analysis, and also Mohr titration method, the presence of chlorine species on the surface of chlorinated samples was confirmed.

Transition metal catalysts (mainly: iron, cobalt and nickel) on various supports are successfully used in a largescale production of carbon nanotubes (CNTs), but after the synthesis it is necessary to perform very aggressive purification treatments that cause damages of CNTs and are not always effective. In this work a preparation of unsupported catalysts and their application to the multi-walled carbon nanotubes synthesis is presented. Iron, cobalt and bimetallic iron-cobalt catalysts were obtained by co-precipitation of iron and cobalt ions followed by solid state reactions. Although metal particles were not supported on the hard-to-reduce oxides, these catalysts showed nanometric dimensions. The catalysts were used for the growth of multi-walled carbon nanotubes by the chemical vapor deposition method. The syntheses were conducted under ethylene - argon atmosphere at 700°C. The obtained catalysts and carbon materials after the synthesis were characterized using transmission electron microscopy (TEM), X-ray diffraction method (XRD), Raman spectroscopy and thermogravimetric analysis (TG). The effect of the kind of catalyst on the properties of the obtained carbon material has been described.