Synthesis of Eu³⁺⁻doped ZnO/Bi2O3 heterojunction photocatalyst on graphene oxide sheets for visible light-assisted degradation of 2,4-dimethyl phenol and bacteria killing

We reported the immobilization of binary heterojunction Eu³⁺-ZnO/Bi₂O₃ over the surface of graphene oxide (GO) sheets by precipitation method to compose a visible light drive photocatalyst. The ternary nanocomposites were characterized by different spectral technique like FESEM, FTIR, XRD, XPS, EDX, HRTEM, UV–visible, PL, HPLC and LCMS analysis. The high specific surface area of 106.0 m²g^-1 of Eu³⁺-ZnO/Bi₂O₃/GO nanocomposites was ascertained by BET adsorption-desorption isotherm. The nano-composite exhibit excellent photo-efficiency for the photodegradation of 2, 4-dimethyl phenol (DMP) under visible region and was almost completely mineralized in 100 min as compared to the bare and binary system. The mineralized products of DMP were analyzed by HPLC and LCMS analysis. The kinetic model suggests the degradation pathway obeys pseudo-first order kinetic. Their antibacterial property were assessed against E. coli bacteria and nearly 90% of gram negative bacteria were killed by using ternary photocatalyst as determined by CFU method. Also, Eu³⁺-ZnO/Bi₂O₃/GO nanocomposites possessed significant recycle efficiency up to six consecutive cycles which is beneficial to minimize the tariff. The improved photo-efficiency is due to the extension towards visible region, increase surface area, and high charge separation in ternary heterojunction.