Engineering of MnO2 Materials at the Nanoscale By PE-CVD for Photoactivated Technologies

Abstract

Photoactivated processes have been widely recognized as cost effective and environmentally friendly routes for both renewable energy generation and purification/cleaning technologies. Great attention has been devoted to the degradation of persistent pollutants in effluent wastewaters, such as dyes from textile, paper and pharmaceutical industries, into harmless products. In addition, increasing efforts have been focused on photoinduced anti-fogging and self-cleaning applications promoted by suitable functional systems endowed with tuneable hydrophobic/hydrophilic properties.In this context, the present work [1] is focused on the development of supported MnO2-based nanomaterials as platforms for the above mentioned photo assisted applications.The selected materials were grown on fluorine-doped tin oxide substrates using plasma enhanced-chemical vapor deposition (PE-CVD) between 100 and 400 °C. This technique allows to gain a fine tuning on the resulting material chemico-physical properties, which, in turn, affect the resulting functional performances. PE-CVD experiments yielded the formation β-MnO2 characterized not only by different hierarchical morphologies (from dendritic structures to quasi-1D nanosystems), but also by a concomitant tailoring of the fluorine content, optical absorptions and band gap values as a function of the adopted growth temperature.Preliminary photo-induced hydrophilicity/photocatalytic functional tests highlighted the possibility of finely tailoring MnO2 nanomaterial performances, thanks to the interplay between their nano-organization, F content and optical absorption capabilities. In addition, the use of Vis illumination instead of UV one did not result in an appreciable performance decrease, paving the way to the use of natural sunlight to activate the target processes. The obtained results, which, to the best of our knowledge, have no precedents to date on the target materials, open challenging perspectives for the development of multi-functional photocatalysts for self-cleaning and antifogging applications, as well as for wastewater treatment.