Příprava kompozitů na bázi Cr2O3/ZnO pro možné využité ve fotokatalýze

Abstract

This submitted bachelor thesis deals with the preparation and characterization of composite materials of different Cr2O3/ZnO ratios (0.02; 0.04; 0.06; 0.10) for possible application in photocatalysis, which were prepared within of this bachelor thesis. The aim of this thesis is to find the material with the best photodegradation performance on the selected dye acid orange 7 (AO7) and phenol with possible industrial application using the prepared catalysts. Subsequently, to improve the properties and photocatalytic effect, additionally, two bulk g-C3N4/(Cr2O3/ZnO=0.02) materials were prepared in two ratios (90 wt%:10 wt% and 80 wt%:20 wt%). After the preparation of the samples, the characterization of materials, using PL spectroscopy, DRS, XRD, IR and photodegradation experiments Vis (420 nm)/UVA (360 nm). From SEM, STEM and EDS methods it was found that Cr2O3 creates so-called flower-like hierarchical heterostructures on ZnO surface. Evaluation of the experimental data revealed that all the prepared composite materials formed nanostructures and were photocatalytically active. In terms of photodegradation, the best composite using AO7 in UVA or Vis irradiation was the material Cr2O3/ZnO=0.02 and bulk g-C3N4/(Cr2O3/ZnO=0.02)=80 wt%:20 wt%, where about 92 % AO7 was degraded. Under UVA light, the best photodegradation activity with 96 % degradation was observed for the bulk g-C3N4/(Cr2O3/ZnO=0.02)=80 wt%:20 wt% composite. In the case of phenol photodegradation, the best composite was bulk g-C3N4/(Cr2O3/ZnO=0.02)=90 wt%:10 wt%, namely in UVA (80 %), VIS (85 %) and Vis-UVA combination (55 %). Cr2O3/ZnO=0.02 composite using phenol worked best in the Vis-UVA combination (photodegradation about 55 %). From the results of the DRS analysis, the energy values of the indirect forbidden bands were found, which in the prepared Cr2O3/ZnO=0.02-0.10 composites tended to decrease as the individual ratios Cr2O3/ZnO increased, respectively.