Multicomponent oxide systems 800-Cu-Mg-Fe-O and 800-Cu-Mg-Fe-O-Ce were tested as catalysts of selective catalytic oxidation of ammonia to dinitrogen (NH₃-SCO) process. Materials were obtained by calcination of hydrotalcite-like compounds at temperature 800 °C. Some catalysts were doped with cerium by the wet impregnation method. Not only simple oxides, but also complex spinel-like phases were formed during calcination. The influence of chemical composition, especially the occurrence of spinel phases, copper loading and impregnation by cerium, were investigated. Materials were characterized by several techniques: X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), low-temperature nitrogen adsorption (BET), cyclic voltammetry (CV), temperature programmed reduction (H₂-TPR), UV-vis diffuse reflectance spectroscopy and scanning electron microscopy (SEM). Examined oxides were found to be active as catalysts of selective catalytic oxidation of ammonia with high selectivity to N₂ at temperatures above 300 °C. Catalysts with low copper amounts (up to 12 wt %) impregnated by Ce were slightly more active at lower temperatures (up to 350 °C) than non-impregnated samples. However, when an optimal amount of copper (12 wt %) was used, the presence of cerium did not affect catalytic properties. Copper overloading caused a rearrangement of present phases accompanied by the steep changes in reducibility, specific surface area, direct band gap, crystallinity, dispersion of CuO active phase and Cu²⁺ accessibility leading to the decrease in catalytic activity.

Graphitic carbon nitride (CN) was synthesized from guanidine hydrochloride (G), melamine (M) and dicyandiamide (DCDA). The CN materials synthetized from the pure precursors and their mixtures were characterized by common methods, including thermal analysis, and their photocatalytic activities were tested by the degradation of selected organic pollutants, such as amoxicillin, phenol, Rhodamine B (RhB). Remarkable changes in their texture properties in terms of particle sizes, specific surface areas (SSA) and consequently their photocatalytic activity were explained by the role of guanidine hydrochloride in their synthesis. The SSA increased due to the release of NH₃ and HCl and its complex reactions with melamine and DCDA forming structure imperfections and disruptions. The photocatalytic activity of the CN materials was found to be dependent on their SSA.