Fabrication, phytotoxicity, and electrochemical performance of rare-earth metal-based mixed La–Ce cobaltite nanospheres: Applications in energy storage and environmental remediation

Abstract

The rare-earth metal-based mixed La–Ce cobaltite (La_1-xCe_xCoO₃) nanospheres were prepared using a hydrothermal synthetic route followed by annealing. La–Ce cobaltites were analyzed using FTIR, XPS, XRD, FESEM, HRTEM, UV–Vis, EDAX, Mott-Schottky and BET techniques. The mixed La–Ce cobaltite catalysts were evaluated for photocatalytic activity (PCA) in the degradation of Methyl orange (MO), Bromophenol blue (BPB), and Mixed dye effluent (MO + BPB, 1:1 v/v). The best-performing Ce-LCO 4 catalyst showed outstanding PCA values for MO (81 %), BPB (90 %), and MO + BPB (84 %) degradation under visible light illumination. Ce-LCO 4 achieved a PCA of 88 % after the fourth cycle, demonstrating excellent recycle characteristics. Radical analysis was carried out using different scavengers, including EDTA, IPA, and p-BQ. LCMS analysis was conducted to identify the byproducts formed during degradation process and to propose a plausible mechanistic degradation pathway. The phytotoxicity effects of dye solutions were analyzed using control, treated, and untreated samples in Lathyrus oleraceus to assess real-time application. CV, GCD, and EIS techniques were employed to evaluate their energy-storage performance. The similar b-values obtained for oxidation (0.66) and reduction (0.69) reactions confirm the combined influence of diffusion-controlled and capacitive characteristics. The most efficient Ce-LCO 4 electrode showed a superior capacitance value of 380 F/g at 0.5 A/g and remarkable cycle life of 93 % after 3000 runs. The symmetrical cell was constructed using Ce-LCO 4 as both the cathode and anode to evaluate its overall performance in a practical application.