Structural and Electrical Characterization of Pure and Al-Doped ZnO Nanorods

Exploitation of green synthesized chromium doped zinc oxide nanorods (NRs) mediated by flower extract of Rhododendron arboreum for highly efficient photocatalytic degradation of cationic dyes Malachite green (MG) and Fuchsin basic (FB)

In this work, green method to synthesize chromium-doped zinc oxide (ZnO) nanorods (NRs) using an aqueous flower extract from Rhododendron arboretum is explored. Herein, chromium-doped ZnO NRs were prepared with different amount of chromium doping, varied as 2-10%. The green synthesized products underwent substantial analysis through X-ray diffraction (XRD), spectroscopic such as ultraviolet spectroscopy(UV-Vis) and scanning electron microscopy (SEM) methods. All samples were found to have hexagonal wurtzite ZnO, with average particle sizes of 52.41, 56.6, 54.44, 53.05, and 56.99 nm, respectively, for 2, 4, 6, 8, and 10% chromium doping in ZnO NRs. The Cr-doped ZnO NRs exhibited remarkable photocatalytic degradation activity of cationic dyes under UV-light, i.e., Malachite Green and Fuchsin Basic with degradation of 99.604 and 99.881%, respectively in 90 min. The reusability tests for these green synthesized Cr-doped ZnO NRs have also been carried out, showed 9-11 cycles with 85% of degradation efficiency. In addition, the Cr-doped ZnO NRs exhibited high selectivity for cationic dyes when experiments against mixture of dyes were performed. Photodegradation kinetics followed the pseudo-first-order model. The flower-extract-stabilized chromium-doped ZnO NRs demonstrated high photocatalytic activity toward malachite green and fuchsin basic dyes, potential material for pollution remediation.

One-Dimensional Mn5Si3 Nanorods: Fabrication, Microstructure, and Magnetic Properties via a Novel Casting-Extraction Route

This study presents a simple and innovative approach for producing one-dimensional Mn₅Si₃ nanorods through a casting-extraction process. In this technique, the Mn₅Si₃ nanorods were synthesized by reacting Mn and Si during brass solidification and extracted by electrochemical etching of the brass matrix. The effect of the cooling rate during casting on the nanorods' dimension, morphology, and magnetic properties was investigated. The results demonstrate that the prepared high-purity Mn₅Si₃ nanorods had a single-crystal D8₈ structure and exhibited ferromagnetism at room temperature. The morphology of the nanorods was an elongated hexagonal prism, and their preferred growth was along the [0001] crystal direction. Increasing the cooling rate from 5 K/s to 50 K/s lead to a decrease in the dimension of the nanorods but an increase in their ferromagnetism. At the optimal cooling rate of 50 K/s, the nanorods had a diameter and length range of approximately 560 nm and 2~11 μm, respectively, with a highest saturation magnetization of 7.5 emu/g, and a maximum coercivity of 120 Oe. These properties make the fabricated Mn₅Si₃ nanorods potentially useful for magnetic storage applications, and this study also provides a new perspective on the preparation of one-dimensional nanomaterials.

Electrical and Optoelectronic Properties Enhancement of n-ZnO/p-GaAs Heterojunction Solar Cells via an Optimized Design for Higher Efficiency

In this study, we report the fabrication of high quality AZO/NRs-ZnO/n-ZnO/p-GaAs heterojunction via a novel optimized design. First of all, the electrical proprieties of gallium arsenide (GaAs) substrates were enhanced via an optimized gettering treatment that was based on a variable temperature process (VTP) resulting in an obvious increase of the effective minority carrier lifetime (τ_eff) from 8.3 ns to 27.6 ns, measured using time-resolved photoluminescence (TRPL). Afterward, the deposition of a zinc oxide (ZnO) emitter was optimized and examined in view of its use both as a light trapping layer (antireflection) and as the n-type partner for the p-type (GaAs) substrate. Nanorod-shaped ZnO was grown successfully on top of the emitter, as an antireflective coating (ARC), to further boost the absorption of light for a large broadband energy harvesting. The interface state of the prepared heterojunction is a key parameter to improve the prepared heterojunction performance, thus, we used laser ablation to create parallel line microgroove patterns in the GaAs front surface. We studied the effect of each step on the performance of the n-ZnO/GaAs heterojunction. The results demonstrate a significant improvement in V_oc, J_sc, fill factor (FF), and an obvious enhancement in the I-V characteristics, exhibiting good diode properties, giving rise to the photovoltaic conversion efficiency (η) from 8.31% to 19.7%, more than two times higher than the reference.