Bimetallic nanoparticles grafted ZnO hierarchical structures as efficient visible light driven photocatalyst: An experimental and theoretical study

Abstract Bimetallic nanoparticles (NPs) exhibiting novel properties due to synergy between the individual elements have sparkled significant interest as a co-catalyst in enhancing the photocatalytic efficiency of semiconductor materials. Here, we report the photocatalytic activity of NiAg NPs embedded on hierarchical ZnO structures (NiAg-ZnO). Structural and morphological investigations through X-ray diffraction and scanning electron microscopy confirmed the formation of NiAg-ZnO. UV-Vis diffuse reflectance spectroscopy revealed the decrease in the bandgap energy of NiAg-ZnO (2.65 eV) in comparison to pristine ZnO (3.1 eV). Interestingly, the rate of photodegradation of methylene blue and rhodamine B dye molecules under visible light irradiation are two to three times enhanced with NiAg-ZnO in comparison to Ag-ZnO. Enhanced visible light absorption and effective charge separation due to the synergistic metal-semiconductor interface formed by the embedment of NiAg bimetallic NPs on ZnO led to the improved photocatalytic activity. Experimental results are further confirmed through the first principle electronic band structure calculations.