Luminescent metal complexes/titanium oxide composites for photocatalytic removal of 2,4-dichlorophenoxyacetic acid

Abstract

Transition metal ions and their oxides have been reported to give enhancement on photocatalytic activity of photocatalyst TiO2 for removal of environmental pollutants [1, 2]. Although luminescent group 11 metal complexes have longer lifetime with characteristic phosphorescent properties; however, modification of the TiO2 with luminescent metal complexes has not been reported so far. In this work, phosphorescent trinuclear pyrazolate complexes from copper, gold and silver metal ions, synthesized from various pyrazole ligands bearing different alkyl side chains, were successfully impregnated as monometallic and bimetallic complexes in TiO2 and then used as a photocatalyst for photocatalytic removal of dichlorophenoxyacetic acid (2,4-D) herbicides [3]. For photocatalytic testing, the resulting monometallic pyrazolate complexes/TiO2 composites showed the improvement of photocatalytic activity due to the efficient reduction of electron-hole recombination and less rigidity of the side chains. Interestingly, the bimetallic complexes/TiO2 composites displayed better photocatalytic activity compared to the monometallic ones due to the efficient electron transfer from one to another complexes that efficiently reduced the electron-hole recombination.