Effect of carrier and axial ligand on the photocatalytic activity of cobalt thioporphyrazine

The photocatalytic activity of cobalt octakis(butylthio) porphyrazine (CoPz(BuS) 8 ) was assessed through photodegradation of the dye rhodamine B (RhB) in water under irradiation with a Xe lamp and aerated conditions. The photocatalytic activity of CoPz(BuS) 8 loaded on Al 2 O 3 or SiO 2 @Fe 3 O 4 nanoparticles or coordinated with an axial azide ligand was also investigated. The results demonstrated that the photocatalytic activity of CoPz(BuS) 8 loaded on Al 2 O 3 was higher than that loaded on SiO 2 @Fe 3 O 4 . The kinetic curves of RhB degradation in aqueous solutions at different pH indicated the pseudo first-order kinetics of the reaction. The highest degradation rate for CoPz(BuS) 8 loaded Al 2 O 3 at pH = 4 after 160 min was 84.6%. However, the advantages of easier separation and recycling as well as the ability to terminate the reaction at any time for the CoPz(BuS) 8 loaded SiO 2 @Fe 3 O 4 cannot be ignored. When electron-rich NaN 3 was coordinated with CoPz(BuS) 8 as an axial ligand and loaded on Al 2 O 3 , the resulting catalyst produced more active oxygen species such as O 2 − and HO • to promote the quicker degradation of RhB than that by the other catalysts. For the N 3 -coordinated CoPz(BuS) 8 loaded on Al 2 O 3 , the reactions at pH = 4 and 7 distinctly deviated from first-order kinetics, and the degradation rate reached 77.6% after 80 min at pH = 4.