Fabrication of heterojunctioned Co3O4-Bi2O3 nanocomposites and their sustainable electrocatalytic degradation of rhodamine B, and direct red 31 dyes.

Heterojunctioned Co3O4-Bi2O3 nanocomposite-based electrocatalysts were prepared by the sol-gel/auto-combustion method. The electrocatalytic performance of the NCs towards rhodamine B (RhB) and direct red 31 (DR 31) dyes in water under current-voltage irradiation was evaluated. The prepared Co3O4-Bi2O3 NCs were examined by XRD, FT-IR, FE-SEM, EDX, and UV-visible spectroscopy analyses. The formation of the Co3O4-Bi2O3 NCs was confirmed by XRD analysis, with crystallite sizes ranging from 52.10 to 57.24 nm. Meanwhile, the FTIR results further proved the formation of a heterostructure, in line with the XRD patterns. FE-SEM investigation presented a spherical Co3O4 NP aggregate flake structure on the Bi2O3 NPs. Meanwhile, UV-Vis DRS spectroscopy revealed improved visible-light absorption, leading to a remarkable decline in band gap of ∼2.85-1.87 eV. Notably, the electrocatalytic results showed that the Co3O4-Bi2O3 NC coded as CBO-6 could effectively degrade 99.61% of RhB within 120 s and 93.32% of DR 31 within 56 min under electrocatalytic irradiation. Scavenger investigation showed that the creation of ROS, particularly hydroxyl radicals, plays a major role in degrading RhB dye. In the stability test, after the 5th cycle, the RhB dye's degradation efficacy was 94.5%. These findings demonstrate that the CBO NCs are appropriate nanomaterials for RhB electrocatalytic degradation, including dye breakdown into carbon dioxide and water.