Exploring the multiferroic and water sensing behavior of Cu/Er co-substituted ferrites as key enablers for next-gen hydroelectric cells

Abstract

Currently, the consumption of energy has enormously risen which in turn causes environmental degradation and this associated degraded environment prompts the research around the devices that produce green energy. Here, we have reported a cost-effective way to produce copper and erbium co-substituted cobalt ferrite nanoparticles [Co1-xCuxFe1.85Er0.15O4, 0.00 ≤ x ≤ 0.09] via sol-gel auto combustion synthesis route. The structural analysis from X-ray diffraction (XRD) measurements confirms the cubic structure of nanoparticles with an average crystallite size of 22 nm. The FT-IR (Fourier transform infrared spectroscopy) studies have revealed the expansion in the octahedral (431-434.85 cm−1) and tetrahedral bands (523-538.82 cm−1) with the increase in the copper content. FESEM-EDX (Field emission scanning electron microscopy) morphology unveils the porous nanostructures with an average particle size around 82.38 nm using ImageJ software. Electrical studies display a net increment in the dielectric constant (ε´) value from 66.908 to 147.97 with an increase in copper concentration from 0 % to 9 % because of the agglomeration of copper and erbium ions at the grain boundaries. It has been also noted that the addition of Cu2+ ions above 6 % into erbium-substituted cobalt ferrite caused a tremendous decrease in the Ms value from 93.75 emu/g to 57.25 emu/g due to weak superexchange interaction upon the co-substitution of copper and erbium ions in cobalt ferrites. The overall value of saturation polarization (Ps) has been improved from 1.009 μC/cm2 to 12.79 μC/cm2 upon increasing the copper concentration in the spinel ferrite. The improvement in ferroelectricity and ferromagnetism in co-substituted cobalt ferrite confirms the presence of multiferroicity in them. The I–V measurements yield prepared hydroelectric cells can deliver a maximum current of 14.772 mA with a power of 11.300 mW for 9 % copper doping in the erbium substituted spinel ferrite while the lowest is reported around 4.08 mA and power of 3.18 mW for only erbium substituted cobalt ferrite. Therefore, the prepared material can be suggested for its useful application in hydroelectric cells.