Novel thiosemicarbazone complexes as single coordinated precursors for noble metal modified nickel oxide nanophotocatalysts

Abstract

Pd2+, Pt2+, Ni2+ and Cu2+ complexes of N-ethyl-2-(2-hydroxybenzylidene) hydrazine-1-carbothioamide (H2L) have been prepared and fully characterized via SCXRD, FTIR, CHNS, UV–Vis, GC-MS, TGA and NMR. Ni2+, Pd2+ and Pt2+ complexes were used as novel single precursors for the preparation of noble metal/metal oxide nanoparticles via solid state thermal decomposition method based on their thermal characteristics. For the first time, one pot preparation of Pd/NiO and Pt/NiO nanoparticles (NPs) was achieved via this method. The prepared nanoparticles were characterized using XRD, TEM, XPS and UV–Vis analytical techniques. The photocatalytic activities of bare and noble metal modified NiO NPs were assessed toward the photodegradation of Methylene Blue dye (MB) under natural solar radiation. The tight contact between noble metals and NiO in addition to the lack of aggregation gave preference to this method. The nanoparticles demonstrated high photocatalytic activities with the following trend Pt/NiO (91.3%)˃Pd/NiO(84.5%)˃NiO (45.0%). The enhanced photocatalytic efficiency in the presence of noble metals was attributed to lower charge carrier's recombination rate and the fermi level energies of noble metal nanoparticles. Total organic carbon (TOC) analysis was performed to assess the mineralization ability of the Pt/NiO nanoparticles (90.7% TOC Removal). For in-depth understanding the reasons behind Pt/NiO nanoparticles photo-reactivity, the revealing of reactive oxidative species (ROS) was achieved through scavenging trapping experiments.