Gold nanoparticles decorated radio-frequency sputtered ZnFe2O4/ZnO nanostructures for photoelectrochemical applications

Abstract

ABSTRACT We report on the growth of ZnFe2O4 (ZFO)/ZnO nanorods by radio-frequency sputtering on indium tin oxide (ITO) coated glass substrates for the photoelectrochemical (PEC) applications. The ZFO nanorods were deposited on (002) oriented ZnO nanorods on ITO at room temperature (RT). The RT-deposited ZFO nanostructures were annealed ex-situ at 500 °C in air. The RT-deposited and the annealed ZFO/ZnO were decorated with gold nanoparticles using a vacuum coating system. In contrast to the paramagnetic nature of bulk ZFO, it is interesting that ZFO based nanostructures show a hysteresis loop with 26 × 103 A/m of saturation magnetization for the RT-deposited sample which increased to 105 × 103 A/m upon annealing the sample at 500 °C. The PEC analysis of Au/ZFO/ZnO/ITO carried out using an electrochemical analyzer has shown more than two times enhancement in photocurrent density for the annealed sample as compared to the RT-deposited sample. The increase of photocurrent density in Au/ZFO after annealing at 500 °C might be attributed to magnetic and surface plasmon resonance leading to spin alignment of conduction electrons.