Direct One-Step Seedless Hydrothermal Growth of ZnO Nanostructures on Zinc: Primary Study for Photocatalytic Roof Development for Rainwater Purification

Abstract

To shift towards the greener city, photocatalytic urban infrastructures have emerged as a promising solution for pollution remediation. To reach this goal, the large bandgap semiconductors, such as nontoxic Zinc Oxide (ZnO), already proved their excellent photocatalytic performances. However, integrating and developing cost-effective and greener photocatalytic surfaces with an easily scaled-up synthesis method and without energy and chemical product overconsumption is still challenging. Therefore, this work proposes to develop a depolluting Zinc (Zn) roof covered by ZnO nanostructures (NSs) using a one-step seedless hydrothermal growth method in 2 h. The feasibility of this synthesis was firstly studied on small areas of Zn (1.25 cm2) before being scaled up to medium-sized areas (25 cm2). The efficiency of this functionalization route for ZnO NSs grown without seed layer was attributed to the presence of Zn2+ sites and the native oxide film on the Zn surface. Their photocatalytic efficiency was demonstrated by removing in less than 3 h the Methylene Blue (MB) and Acid Red 14 (AR14) in both DI water and rainwater under UV-light. Promising results were also recorded under solar light. Therefore, the photocatalytic Zn roof functionalized by ZnO NSs is a promising route for rainwater purification by photocatalysis.

Seedless hydrothermal growth of hexagonal prism ZnO for photocatalytic degradation of methylene blue: the effect of pH and post-annealing treatment

“…The calculated band gap is 3.75, 3.80, and 3.70 eV for ZnO-1, ZnO-2, and ZnO-3, respectively. These values are quite higher as compared to previously published work that shows the ZnO bandgap around 3.0-3.4 eV [5,28,40]. Here, a lower pH solution (ZnO-2) has a higher band gap, while the higher pH (ZnO-3) shows otherwise.…”

“…Among the various renewable energy sources, solar energy is a viable option to address the abovementioned problems independently. A previous study showed that rooftops have the potential to be used as a large photocatalytic reactor, using sunlight for rainwater purification [5]. A semiconductor photocatalyst is one of the most suitable for green energy production because it is relatively cheap and easy to implement.…”

Integrated Design and Control of a Sustainable Stormwater Treatment System

“…On the other hand, in [12], the authors use a photocatalysis method for rainwater purification, where they develop a decontaminating zinc (Zn) roof covered by ZnO nanostructures (NS) using a one-step seedless hydrothermal growth method in 2 h.…”

Tuning Growth of ZnO Nano-Arrays by the Dewetting of Gel Layer

“…Research on ZnO nanomaterials has been booming since the 1990s [1][2][3][4][5][6]. Due to its excellent characteristics, zinc oxide has always maintained a high degree of attention in the fields of energy, environment, biology, and detection [7][8][9][10][11][12][13]. In these decades of research, controllable growth and cost reduction are two aspects to which people have been committed.…”