Cu/CuO-Doped ZnO Nanocomposites via Solution Combustion Synthesis for Catalytic 4-Nitrophenol Reduction

Abstract

The synthesis of optoelectrically enhanced nanomaterials should be continuously improved by employing timeand energy-saving techniques. The porous zinc oxide (ZnO) and copper-doped ZnO nanocomposites (NCs) were synthesized by the time-and energy-efficient solution combustion synthesis (SCS) approach. In this SCS approach, once the precursor− surfactant complex ignition point is reached, the reaction starts and ends within a short time without the need for any external energy. The TGA−DTA analysis confirmed that 500 °C was the point at which stable metal oxide was obtained. The doping and heterojunction strategy improved the optoelectric properties of the NCs more than the individual constituents, which then enhanced the materials' charge transfer and optical absorption capabilities. The porosity, nanoscale crystallite size (15−50 nm), and formation of Cu/CuO-ZnO NCs materials were confirmed from the XRD, SEM, and TEM/HRTEM analyses. The obtained d-spacing values of 0.275 and 0.234 nm confirm the formation of ZnO and CuO crystals, respectively. The decrease in photoluminescence intensity for the doped NCs corroborates a reduction in electron−hole recombination. On the Mott−Schottky analysis, the positive slope for ZnO confirms the n-type character, while the negative and positive slopes of the NCs confirm the p-and n-type characters, respectively. A diffusion-controlled type of charge transfer process on the electrode surface was confirmed from the cyclic voltammetric analysis. Thus, the overall analysis shows the applicability of the less expensive and more efficient SCS for several applications, such as catalysis and sensors. To confirm this, an organic catalytic reduction reaction of 4-nitrophenol to 4-aminophenol was tested. Within three and a half minutes, the catalytic reduction result showed the great potential of NCs over ZnO NPs. Thus, the energy-and time-saving SCS approach has a great future outlook as an industrial pollutant catalytic reduction application.

Chemistry of iron and copper co-doped zinc oxide: reduction and degradation of pollutants

“…Confirming the presence of optical-electrical properties using Mott-Schottky analysis due to copper-based doping and heterojunction formation has been performed in different studies. 71,72 However, determining the flat band potential for co-doped materials is complex and is not also proposed in this study.…”

A Review on Synthesis and Characterization of Copper Doped Zinc Oxide Nanocomposites

“…It is examined from ancient era that micro molecules has been largely introduced in various fields of medicine, Ayurveda, cosmetics, paints and each essentialities if day to day life usages. Older ancient facilities was equipped with enamourous nanoparticles in the form of "Bhasma" that was elaborated in ancient medicines, as this era developed the ancient processes of nanoparticles formation in modified methodology in bulk process [1,2]. Nanocomposites developed from metal implementation in various plant materials was largely introduced in long ago centuries, which was implemented as medicine in fever, cough, cancer treatment, arthritis, stomach pain and many more irregularities effecting animal and human health [3].…”

“…Buzuayehu Abebe et.al. (2023) implemented solution combustion process through mixing same ration of zinc chloride and copper chloride leading to foam formation by addition of 0.5M NaOH solution till pH 8, centrifuged at 10000 rpm, ovened at 80℃, muffled at 400℃ for three hours leading to black color powder [2]. Kashif Ali Khan et.al.…”

Bimetallic CuO−ZnO Hybrid Nanocomposite Materials for Efficient Remediation of Environmental Pollutants

“…Even though the doping of copper in the ZnO lattice improves the optoelectronic properties better than that of the separate constituents. Besides, forming a p‐n junction between CuO and ZnO also creates an electric field greater than their respective constituents and enhances the materials′ charge transfer and optical absorption properties [13] . These unique properties of copper oxide‐based materials make them widely studied materials for catalysts, optics, and optoelectronics applications [14] .…”

“…Besides, forming a p-n junction between CuO and ZnO also creates an electric field greater than their respective constituents and enhances the materials' charge transfer and optical absorption properties. [13] These unique properties of copper oxide-based materials make them widely studied materials for catalysts, optics, and optoelectronics applications. [14] To enhance the catalytic characteristics of CuO nanoparticles, we have doped CuO with various amounts of ZnO in the current work.…”