Fe-induced morphological transformation of 1-D CuO nanochains to porous nanofibers with enhanced optical, magnetic and ferroelectric properties

Abstract

The present work reports the synthesis of self-assembled 1-D polycrystalline Fe doped CuO nanostructures (Cu 1Àx Fe x O, x = 0.02 (SP2), 0.05 (SP5), 0.10 (SP10)) using a wet chemical approach. The surface analysis of these nanostructures by X-ray photoelectron spectroscopy indicated Fe to be present as Fe 3+ . The doping of Fe (2 to 10%) causes exchange of Cu in CuO and creates point defects -oxygen vacancies, which are manifested by the change in morphologies of doped nanostructures from nanochains to nanofibers, a reduction in the size of CuO NPs from 19 to 5 nm, the red shifted optical absorption and fluorescence bands associated with an increase in the fluorescence lifetime(s) and blue shifted Raman spectra. The field dependent magnetization (M-H) measurements at room temperature show that for SP10 the magnetization value increases by a factor of about 3 as compared to that of the undoped sample and the superparamagnetic behavior increases with increasing Fe-content. Whereas, at 5 K it exhibits ferromagnetic behavior with increasing values of coercivity (1564 Oe) and retentivity (0.19 emu g À1 ) and exchange bias effect decreasing with increased doping of Fe. The room temperature polarization versus electric field measurements at 200 Hz show weak ferroelectric behavior for all samples and increases with increasing Fe content in the sample. Dielectric constant and dielectric lossshow decreasing values with increasing frequency. A correlation between the observed changes in morphology with optical, magnetic and ferroelectric properties upon doping of Fe has been analyzed.

Role of compensating Li/Fe incorporation in Cu0.945Fe0.055−xLixO: structural, vibrational and magnetic properties

“…A shake-up satellite feature is observed at about 717.59 eV which is in close agreement with available literature, indicating that Fe is in +3 valence state. 35 There is no peak in the region 706-707 eV, indicating the absence of metallic Fe.…”

“…In CuO, 4A u + 5B u are IR active and A g + 2B g are Raman active modes. 34 Raman active modes (A g , B g , and B g ) appear at $293, 342 and 628 cm À1 respectively 35,36 for all samples [Fig. 3].…”

Anion Vacancy Engineering in Electrocatalytic Water Splitting

“…Guar et al. detected the existence of O vacancies in Fe‐CuO by the positively shifted peaks due to the contracted lattice (Figure 3b) [37] . Moreover, some other spectroscopic techniques, including electron paramagnetic resonance (EPR) and electron spin resonance (ESR) spectra, conduce to the analysis of the electronic environment around vacancies [38] .…”

“… (a) PAS for various MoS 2 samples [35] . (b) Raman spectra of SP2, SP5 and SP10 [37] . (c) EPR spectra of CoSe 2 UNM vac and CoSe 2 NS [39] .…”

Effect of Doping Ce Ions on Morphology and Photocatalytic Activity of CuO Nanostructures

“…It is known that the well‐controlled synthesis and fabrication of CuO NSs with disparate morphological sizes, morphological shapes, and structures contribute to the properties of CuO nanomaterials. Recently, various morphological CuO NSs such as nanowires, nanoribbons, nanofibers, nanotubes, flower‐like structures, and cocoon‐shaped structures have been studied intensely and synthesized by hydrothermal method, electrochemical method, chemical bath deposition method, sol‐gel method, etc . The performances of CuO NSs depend on the morphological sizes, morphological shapes, and nanocrystals.…”