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

Buzuayehu Abebe; Dereje Tsegaye; Chaluma Sori; Ravikumar Chunchana Kuppe Renuka Prasad; H C Ananda Murthy

doi:10.1021/acsomega.3c00141

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

ACS Omega. 2023 Mar 2;8(10):9597-9606. doi: 10.1021/acsomega.3c00141. eCollection 2023 Mar 14.

Authors

Buzuayehu Abebe¹, Dereje Tsegaye¹, Chaluma Sori¹, Ravikumar Chunchana Kuppe Renuka Prasad², H C Ananda Murthy^{1

3}

Affiliations

¹ Department of Applied Chemistry, School of Applied Natural Science, Adama Science and Technology University, P.O. Box 1888, Adama 1888, Ethiopia.
² Research Centre, Department of Science, East-West Institute of Technology, Bangalore 560091, India.
³ Department of Prosthodontics, Saveetha Dental College & Hospital, Saveetha Institute of Medical and Technical Science (SIMATS), Saveetha University, Chennai 600077, Tamil Nadu, India.

Abstract

The synthesis of optoelectrically enhanced nanomaterials should be continuously improved by employing time- and 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.