Porous LaFeO₃ walnuts for efficient visible light driven photocatalytic detoxification of harmful organic pollutants

The orthorhombic crystalline walnuts consisting of nanoparticles with an average size of ∼72 nm of stoichiometric LaFeO₃ (LFO) offering 10.280 m²/g surface area and band gap of 2.29 eV exhibited the photocatalytic degradation of multiple organic dyes under the Xenon lamp and sunlight. The kinetic study revealed 96.02, 90.22, and 82.45% degradation of Crystal Violet (CV), Methylene Blue (MB), and Rhodamine B (RhB) with a rate constant of 0.012, 0.0096, and 0.0073 min⁻¹, respectively, after continuous irradiation of 240 min. The LFO walnuts delivered sunlight driven degradation of ∼91% for organic CV dye. The scavenger and PL study revealed the active involvement of h⁺ and O₂⁻ in the photocatalytic degradation of dyes. Photocatalytic degradation intermediates were identified using the mass spectroscopy (ESI-LCMS) technique. N-de-methylation of organic dyes during irradiation followed by cleavage of conjugated chromophore structure and opening of the benzene ring in CV; however, oxidation in MB; leads to the formation of ecological compounds along with the CO₂ and H₂O. Our results propose the LFO walnuts as an excellent candidate for stable and sunlight driven degradation of organic dyes.