Exploring the bifunctional capabilities of Ni-doped PbAl₂O₄ nanoparticles for supercapacitor and photocatalytic activity

In this study, bare and Ni-doped PbAl₂O₄ nanoparticles (with Ni concentrations of 0.020, 0.040 and 0.060 M) were successfully synthesized via a co-precipitation route to explore their multifunctional properties using various characterization techniques. The XRD patterns confirmed the formation of an orthorhombic structure with no secondary phases, indicating the successful incorporation of Ni into the PbAl₂O₄ lattice. Morphological analysis using FESEM and HR-TEM revealed that the Ni-doped (0.040 M) PbAl₂O₄ sample exhibited spherical and rod-like nanoparticles with moderate agglomeration. UV-DRS showed a progressive reduction in the optical band gap with increasing Ni content, with the 0.040 M doped sample exhibiting a lower band gap value. The PL spectra indicated a significant suppression of charge carrier recombination in the Ni-doped samples, particularly in the 0.040 M Ni-doped sample, which correlated with its photocatalytic activity. BET analysis revealed that the Ni-doped (0.040 M) PbAl₂O₄ nanoparticles possessed a specific surface area of 18.8478 m² g⁻¹. The electrochemical performance was studied through CV and GCD analysis, confirmed the pseudocapacitive nature. The Ni-doped (0.040 M) sample delivered a specific capacitance value of 575 F g⁻¹ at 1 A g⁻¹. EIS analysis indicated low charge transfer resistance and efficient ion diffusion. The photocatalytic degradation of Congo red and crystal violet dyes under UV light exposure demonstrated superior degradation efficiency for the Ni-doped (0.040 M) PbAl₂O₄ sample, achieving 94 and 91% degradation, respectively. Overall, Ni-doped PbAl₂O₄ nanoparticles, especially at the optimal concentration (0.040 M), exhibited dual functionalities as promising electrode materials for supercapacitors and efficient photocatalysts for removing organic pollutants, making them strong candidates for addressing energy storage and environmental remediation challenges.