Bergera koenigii stem-derived magnetic biochar nanocomposite for enhanced photocatalytic efficiency of Ce1-xZnxO2-δ NPs under UV light for the degradation of methyl orange

Abstract

The production of mesoporous, nanocrystalline, Zn-doped CeO2 nanoparticles (NPs) at various concentrations of Zn, Magnetic biochar (MBC)-Zn-doped CeO2 nanocomposites (NC), their characterizations, and photocatalytic degradation analysis are presented in this study. The synthesis of MBC-Ce0.91Zn0.09O2-δ NC is based on the carbonization of an iron oxide precursor with powdered Bergera koenigii stem (curry leaf stem). XRD and TEM results confirm polycrystalline, spherical fluorite Ce1-xZnxO2-δ NPs and MBC-Ce0.91Zn0.09O2-δ NC formations. The crystallite size varies from 4–12 nm with an increase in the doping concentration of Zn and 8.55 nm for MBC-Ce0.91Zn0.09O2-δ NC. XPS analysis displays the valence states and surface chemical composition of the as-prepared MBC-Ce0.91Zn0.09O2-δ sample. BET analysis provides the surface area (17–32 m2/g for Ce1-xZnxO2-δ NPs and 142 m2/g for MBC-Ce0.91Zn0.09O2-δ NC) and pore size (25–45 Å for Ce1-xZnxO2-δ NPs and 17.35 Å for MBC-Ce0.91Zn0.09O2-δ NC) of all the samples. All the samples possess good UV absorption in the range of 200–400 nm, and the bandgap energy of the as-prepared samples decreased from 3.088 to 2.79 eV with increased dopant concentration and on-load magnetic biochar. The oxygen deficiencies and lattice deformations of the as-prepared samples are studied using Raman, FTIR, and photoluminescence (PL) spectra. The degradation efficiency of 5 ppm Methyl Orange (MO) is analyzed using 50 mg catalytic (Ce1-xZnxO2-δ NPs, MBC-Ce0.91Zn0.09O2-δ NC) dosage by maintaining the pH of the solution as 4. After 16 min of UV irradiation, the as-synthesized Ce0.91Zn0.09O2-δ NPs and MBC-Ce0.91Zn0.09O2-δ NC exhibit 91 % and 97 % decolorization and 90 % and 94 % total organic carbon (TOC) removal efficiency. Regression analysis is performed to evaluate each model's applicability to photocatalytic degradation. The regeneration experiments on Ce0.91Zn0.09O2-δ NPs and MBC-Ce0.91Zn0.09O2-δ NC prove the stability of these catalysts for activating MO.