Vol.:(0123456789) 1 3 Journal of Materials Science: Materials in Electronics https://doi.org/10.1007/s10854-019-02839-z Glycine-A bio-capping agent for the bioinspired synthesis of nano-zinc oxide photocatalyst Parita Basnet 1  · Dhrubajyoti Samanta 1  · T. Inakhunbi Chanu 2  · Satadru Jha 3  · Somenath Chatterjee 1 Received: 12 September 2019 / Accepted: 27 December 2019 © Springer Science+Business Media, LLC, part of Springer Nature 2020 Abstract Structural modifcation of nanoparticles (NPs) for application-specifc study is timely. In the present investigation, an attempt has been made for the bioinspired synthesis of zinc oxide (ZnO) NPs possessing diferent morphologies using glycine as the bio-capping agent. A variation in the amount of glycine during low-temperature mediated solid-phase synthesis indicated that a higher ratio of glycine directed the ensemble of nanohexagons into nanobundles which further formed nano-fower buds- like morphology, while least concentration formed agglomerated NPs and moderate concentration of glycine was able to modify the NPs’ structure into nanorods. On the other hand, the utilization of solution-phase synthesis methods, i.e. co- precipitation and hydrothermal, led to the formation of thinner and thicker ZnO nanosheets, respectively. In terms of crystal- line structure, not much diference was observed in the lattice parameters or the unit cell of the crystal, with approximately similar crystallite sizes. From Fourier transform infrared spectroscopy, the functionalization of glycine from both the amine and the carboxyl group was noted. Further, it was found that the morphology and photoluminescence emission spectra of the samples were inter-related, wherein higher the agglomeration of the particles, greater the intensity of the visible region defect band was observed. The as-synthesized ZnO-photocatalysts were then employed for the degradation of rhodamine B (RhB), a major efuent of the textile industry. The photocatalytic activity of the samples was found to depend upon the surface area, which in turn was related to the morphology and the magnitude of green emission defect states. About 99% RhB degradation was obtained with ZnO possessing nano-fower buds-like morphology within 60 min of sunlight irradiation. Additionally, the role of reactive oxidative species and the stability of this photocatalyst were investigated. 1 Introduction For the past many years, organic stabilizing agents, such as oleic acid, thioglycerol, and so on [1–6] along with other polymers and surfactants, have been utilized in the synthesis of zinc oxide (ZnO) nanoparticles (NPs), which impart the material its stability and also function as a structure modi- fer [7–13]. In recent times, stabilization of NPs using bio- capping agents, such as amino acids [14, 15], plant extracts [8, 13, 16], and so on, have attracted substantial interest since such structures are bio-compatible and therefore may be employed for biological applications including DNA or drug delivery, imaging, cosmetics, and others [17, 18]. Thus, amino acids (building blocks of protein) may be deliber- ated as ideal bio-compatible stabilizing agents. Based on the characteristics of their side chains, amino acids are catego- rized into various groups, wherein, the physical properties of the side chains may act as an infuence during the interac- tion of amino acid residues with other compounds. Sreevalsa et al. [19] reported the synthesis of L-histidine-capped ZnO nanocrystals possesing potential bio-imaging application with regard to the intense photoluminescence (PL) emis- sion observed at wavelength of ~ 527 nm. Another study based on the biological application of amino acid capped ZnO nanostructures (NSs) has been put forth by Ramani et al. [20]. They utilized three diferent types of amino acids, namely, L-alanine, L-threonine, and L-glutamine for the cap- ping purpose of ZnO NSs, which resulted in the formation of various morphologies of ZnO. These NSs were then tested * Somenath Chatterjee somenath@gmail.com; somenath.c@smit.smu.edu.in 1 Centre for Material Science and Nanotechnology, Sikkim Manipal Institute of Technology, Sikkim Manipal University, Gangtok, Sikkim, India 2 Department of Chemistry, Nar Bahadur Bhandari Degree College, Gangtok, Sikkim, India 3 Department of Chemistry, Sikkim Manipal Institute of Technology, Sikkim Manipal University, Gangtok, Sikkim, India