Investigation of photocatalitic performance of metal nanoclusters decorated on various supporting material surfaces for the Cr(VI) reduction and methylene blue degradation

In this study, titanium oxide carbon nitride and benzene doped carbon nitride support materials were synthesized in accordance with the literature. Silver (Ag), gold (Au), and palladium (Pd) monometallic nanoclusters were prepared using the classical impregnation-reduction method. For this purpose, the steps of loading the metal salt in the solution phase at room temperature on the surface of the support material and then reducing it using NaBH4 were followed. Optical, electronic, morphological and structural analyzes of the prepared nanomaterials were defined using devices such as FT-IR, UV-DR, BET, P-XRD, XPS, SEM, EDX and TEM. The photocatalytic activities of the obtained TiO2-C3N4 and BD-C3N4 supported monometallic nanomaterials were investigated in the degradation of methylene blue under visible light and the reduction reaction of Cr(VI) ion to Cr(III). As a result of photocatalytic investigations, it was determined that the photocatalytic activities of monometallic 0.5%Au@TiO2-C3N4 0.5%Pd@TiO2-C3N4 and %3Pd@BD-C3N4 nanocatalysts showed higher photocatalytic efficiency than the support material and other monometallic nanocatalysts. The average particle sizes of Ag, Pd and Au nanoparticles on the support materials from the images obtained in the TEM analysis were defined using the image-j nanoparticle size calculation program. Particle size for 0.5%Pd@TiO2-C3N4 catalyst is in the range of 1.8-3.8 nm with an average diameter of 1.9 nm, for 0.5%Au@TiO2-C3N4 catalyst, the particle size is in the range of 1.2-3.4 nm with an average diameter of 1.5 nm, and % The particle size for the %3Pd@BD-C3N4 catalyst was found to be in the range of 2-5.5 nm and an average diameter of 4 nm. However, the reusability of 0.5%Au@TiO2-C3N4, 0.5%Pd@TiO2-C3N4 and %3Pd@BD-C3N4 photocatalysts was evaluated with the recyclable test. According to the test results, 0.5%Au@TiO2-C3N4 photocatalyst showed 78% degradation in the fourth cycle, 0.5%Pd@TiO2-C3N4 photocatalyst showed 88% degradation in the third cycle and 0.5%Pd@TiO2-C3N4 photocatalyst showed 68% degradation in the third cycle in methylene blue degradation. In the reusability test performed in the reduction reaction of Cr(VI) ion to Cr(III); 0.5%Au@TiO2-C3N4 photocatalyst showed 85% reduction in the third cycle, 0.5%Pd@TiO2-C3N4 photocatalyst showed 84% reduction in the third cycle, and %3Pd@BD-C3N4 photocatalyst showed 85% reduction in the third cycle. It is predicted that these nanocatalysts, which have been prepared with successful results in these studies, can be used to remove different toxic dyestuffs from wastewater or to make them useful, especially in the degradation of methylene blue and Cr(VI) reduction reactions.