Wiyogo Prio Wicaksono, Nabilla Dinnia, Ika Yanti, Gani Purwiandono, Ganjar Fadillah

Green synthesis of Au coated on ZnO nanoparticles using orange peel extract and its application for electrochemical detection of formaldehyde

Introduction

Green synthesis of au coated on zno nanoparticles using orange peel extract and its application for electrochemical detection of formaldehyde . Discover green synthesized Au/ZnO nanoparticles using orange peel extract for sensitive and selective electrochemical formaldehyde detection. High-performance sensor developed.

Abstract

We report the facile preparation of Au coated ZnO nanoparticles via a two-step green synthesis route. The aqueous of orange peel extract (OPE) was used both as biocomplexing and bioreducing agents, while the Zn(NO3)2 and HAuCl4 were employed as precursors. Initially, OPE was prepared to synthesize the ZnONPs, followed by the reduction of HAuCl4, generating Au coated on ZnO nanoparticles (Au/ZnONPs). The IR spectra at around 438.95 cm-1 confirmed the presence of Zn-O absorption in the nanoparticles, while it was not observed in the OPE. Further characterization using XRD and SEM-EDX indicated that the spherical of Au was successfully coated on the sponge-like structure of ZnO with the crystalline size of ZnONPs and Au/ZnONPs were 21.30 and 26.67 nm, respectively.  The modified Au/ZnONPs on graphite paste electrode showed the excellent electrochemical detection of formaldehyde solution by the linearity range from 1 to 100 mM (R2=0.9945) with LOD of 10.27 mM and RSD of 0.39%. In addition, the modified electrode showed high selectivity toward formaldehyde, instead of ethanol.

Review

This manuscript presents a compelling investigation into the green synthesis of Au-coated ZnO nanoparticles (Au/ZnONPs) utilizing orange peel extract (OPE), followed by their application in the electrochemical detection of formaldehyde. The work is particularly noteworthy for its environmentally benign approach, employing OPE as both a biocomplexing and bioreducing agent, thus aligning with contemporary trends in sustainable materials science. The two-step synthesis route, starting with ZnONPs preparation and subsequently coating with gold, is clearly articulated and offers a practical method for developing bimetallic or hybrid nanostructures with tailored properties. Overall, the study offers a significant contribution to the fields of green nanotechnology and electrochemical sensing. The detailed characterization techniques employed provide robust evidence for the successful synthesis and structural integrity of the Au/ZnONPs. Infrared spectroscopy confirms the presence of Zn-O bonds, while X-ray diffraction data quantifies the crystalline sizes of both bare ZnO and the Au/ZnO composite, demonstrating a slight increase upon gold coating. Furthermore, SEM-EDX analysis reveals the interesting morphology, depicting spherical Au nanoparticles uniformly coated on a sponge-like ZnO support, which is crucial for understanding the enhanced performance. These findings collectively establish a strong foundation for the material's structural attributes and validate the efficacy of the green synthesis method in producing well-defined hybrid nanomaterials. The utility of the synthesized Au/ZnONPs is impressively demonstrated in the context of electrochemical formaldehyde detection. The modified graphite paste electrode exhibits excellent analytical performance, characterized by a broad linearity range (1 to 100 mM) with a high correlation coefficient (R2=0.9945), a low relative standard deviation (RSD of 0.39%), and significant selectivity over ethanol. While the reported limit of detection (LOD) of 10.27 mM is suitable for certain applications, exploring strategies to further enhance sensitivity for real-world trace analysis, especially in environmental or biological samples, would be a valuable direction for future work. Nevertheless, the combination of a green synthesis strategy with promising electrochemical sensing capabilities makes this a highly commendable piece of research with strong potential for further development.

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