Role of Eu3+ concentration on photoluminescence and electrochemical studies of Bi2Cr4O15 nanoparticles

In the current study, Bi₂Cr₄O₁₅ (BCO):Eu(1-9 mol%) nanoparticles are synthesized using Aloe vera gel extract. The as-formed samples are calcined at 600 °C for 3 h. The Bragg reflections of BCO NPs confirms the formation of triclinic crystal structure. The addition of Eu${}^{3+}$ dopant did not alter the Bragg reflections except the variations in intensity. The crystallite size decreases with increase in dopant concentration from 20 to 13 nm. The surface morphology of BCO:Eu(1 mol%) NPs reveals agglomeration along with irregular and rod-like shapes. This agglomeration, size and shape of the NPs changes with increase in dopant concentration. The optical energy band gap increases from 2.73 to 2.85 eV with increase in dopant concentration. The photoluminescence emission spectra recorded at 285 nm excitation shows a prominent peak at 572 nm, which is attributed to the characteristic Eu${}^{3+}$ ⁵D₀ $\to$ ⁷F₂ transition of Eu doped materials. The CIE coordinates lies well within the yellow region. The average correlated color temperature was found to be 4077 K. This material is often used in workspaces, industrial areas, and outdoor lighting etc. The electrochemical analysis of Eu${}^{3+}$-doped Bi₂Cr₄O₁₅ shows specific capacitance values of 29.44–63 F/g, with the lowest charge transfer resistance (Rct) observed at 9 mol% doping. Nyquist plots reveal improved conductivity and ion diffusion, supported by a reduction in the Warburg coefficient ($\sigma$) from 502.30 to 270.53. These findings highlight 9 mol% as the optimal doping concentration, making the material promising for electrochemical applications.