A traditional semiconductor (WO₃) was synthesized from different precursors via hydrothermal crystallization targeting the achievement of three different crystal shapes (nanoplates, nanorods and nanostars). The obtained WO₃ microcrystals were analyzed by the means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and diffuse reflectance spectroscopy (DRS). These methods contributed to the detailed analysis of the crystal morphology and structural features. The synthesized bare WO₃ photocatalysts were totally inactive, while the P25/WO₃ composites were efficient under UV light radiation. Furthermore, the maximum achieved activity was even higher than the bare P25’s photocatalytic performance. A correlation was established between the shape of the WO₃ crystallites and the observed photocatalytic activity registered during the degradation of different substrates by using P25/WO₃ composites.

In the present work, the influence of a gold nanoparticle’s shape was investigated on the commercially available Evonik Aeroxide P25. By the variation of specific synthesis parameters, three differently shaped Au nanoparticles were synthetized and deposited on the surface of the chosen commercial titania. The nanoparticles and their composites’ morphological and structural details were evaluated, applying different techniques such as Diffuse Reflectance Spectroscopy (DRS), X-ray Diffraction (XRD), and Transmission Electron Microscopy (TEM). The influence of the Au nanoparticles’ shape was discussed by evaluating their photocatalytic efficiency on phenol and oxalic acid degradation and by investigating the H₂ production efficacy of the selected composites. Major differences in their photocatalytic performance depending on the shape of the deposited noble metal were evidenced.

Carbon aerogel (CA) and xerogel (CX) were proposed as new carbon adsorbent materials for Cu and Cd ions from contaminated water (synthetic water samples). These materials were prepared by a sol-gel process that involves a polycondensation of resorcinol and formaldehyde in Na 2 CO 3 catalysis, followed by a drying step, either in supercritical conditions of CO 2 to aerogel obtaining or in normal conditions to xerogel obtaining, and a pyrolytic step. Nitrogen adsorption, AFM, SEM, TEM and XRD were used for morpho-structural adsorbent investigation. Cu and Cd ions adsorption experiments were carried out in batch conditions under magnetic stirring. Adsorbent quantity and grain size influence over the adsorption efficiency were considered. Adsorption results expressed as adsorption capacities showed that prepared CA is a better adsorbent than CX. Adsorption capacities up to 14.2 mg g-1 and 8.5 mg g-1 were obtained for Cd 2+ and Cu 2+ adsorption on CA, respectively.

Iron doped carbon aerogels have been prepared by sol-gel polymerization of potassium salt of 2,4-dihydroxybenzoic acid with formaldehyde followed by an ion-exchange process between K+ doped wet gel and Fe(II) or Fe(III) ion aqueous solutions. The resulted Fe(II) or Fe(III) doped gels have been dried in supercritical conditions with liquid CO2 and then pyrolyzed in high temperature resulting two types of iron doped carbon aerogels. These aerogels were morpho-structural investigated by using BET method, transmission electron microscopy, X-ray diffraction and elemental analysis. Also, these iron doped carbon aerogels (CAD-Fe(2+) and CAD-Fe(3+)) were tested for realization of modified carbon paste electrodes. CAD-Fe(2+) aerogel showed better electrochemical activity than CAD-Fe(3+) and also a good electrocatalytic activity towards H2O2 reduction (expressed by an electrocatalytic efficiency of 404% measured at – 500 mV vs. SCE).