Role of linker molecules on morphology of tripodal ligands based functionalized ZnO nanoparticles and its effect on photocatalysis

Photocatalysis using semiconductor nanoparticles is very popular method to degrade toxic dyes used in several industrial processes. ZnO is widely accepted material for application in photocatalysis because of its wide band gap (3-3.7 eV), biocompatibility and cost effectiveness. The properties of a photocatalyst can be tuned to desirable band gap, adsorption and catalytic sites by decreasing its size and modifying its surface. In this manuscript, ZnO nanomaterials with modified surface are prepared by using surface directing groups like urea/ thiourea based tripodal ligands which help in obtaining particles with variable size as well as the surface characteristics. More importantly, synthesis of these ZnO nanoparticles is carried out at room temperature i.e. 30-40 degrees C. Four tripodal ligands A i.e. 1,1 ',1 ''-(2,2 ',2 ''-nitrilotris (ethane-2,1-diyl))tris(3-(4-nitrophenyl)urea, B i. e. 1,1 ',1 ''-(2,2 ',2 ''-nitrilotris(ethane-2,1-diyl))tris(3-(naphthalen-1-yl)urea), C i.e. [1,1 ',1 ''-(2,2 ',2 ''-nitrilotris (ethane-2,1-diyl))tris(3-(4-nitrophenyl)thiourea)] and D i.e. [1,1 ',1 ''-(2,2 ',2 ''-nitrilobis(ethane-2,1-diyl))tris(3-(4-nitrophenyl)thiourea)]. These ligands are further used as structure directing agents for the synthesis of surface modified ZnO nanomaterials i.e. A-ZnO (regular hexagon), B-ZnO (fibrous mesh), C-ZnO (spherical) and D-ZnO (distorted spherical). Their photocatalytic study towards degradation of Rhodamine B dye revealed the efficiency of A-ZnO as 78 % while others as -97-98 % in 60 min. Among them, C-ZnO and D-ZnO degraded -94 % dye molecules within 30 min in absence of light (dark).

Automated summary

Photocatalysis using ZnO nanoparticles with modified surface prepared by using urea/thiourea-based tripodal ligands showed efficient degradation of Rhodamine B dye. The A-ZnO nanoparticles exhibited a degradation efficiency of 78% in 60 min, while B-ZnO, C-ZnO, and D-ZnO achieved degradation efficiencies of 97-98% within the same time frame. Notably, C-ZnO and D-ZnO degraded 94% of the dye molecules within 30 min even in the absence of light.