Gel-combustion-synthesized ZnO nanoparticles for visible light-assisted photocatalytic hydrogen generation

Zinc oxide nanoparticles (ZnO NPs) synthesized by the gel combustion technique using a bio-fuel, cassava starch (root tubers of Manihot esculenta), have been characterized by various techniques. The X-ray diffraction pattern reveals hexagonal wurtzite structure. The particle size averaged around 45 nm with an excellent band gap of 2.5 eV. The scanning electron and transmission electron microscopic images confirm the ZnO NPs to be agglomerated with loop- and chain-like morphology. The ZnO NPs prepared by this method is a promising candidate for photocatalytic hydrogen generation (41 μmol h−1 g−1) under UV light illumination and (140 μmol h−1 g−1) under visible light illumination.