Facile synthesis of PANI and rGO supported Y/Pr co-doped ZnO: boosted solar light-driven photocatalysis

A significant amount of pollutants containing organics, toxic elements, and heavy metals are discharged daily from the textile and pharmaceutical industries into clean water leading to various diseases worldwide. In the present work, sunlight-mediated yttrium (Y)-praseodymium (Pr) co-doped ZnO photocatalysts anchored on reduced graphene (rGO) and conducting polymer (PANI) were synthesized via co-precipitation and ultrasonication approach for the photodegradation of synthetic dyes. The as-synthesized catalysts were characterized through XRD, FTIR, Raman, FE-SEM, UV–Vis, and PL for structural, morphological, and optical studies. The XRD diffraction peaks have confirmed the successful doping of Y and Pr without altering the basic hexagonal structure of ZnO and anchoring of rGO and PANI. FTIR demonstrated the Zn–O bond vibration, and Raman exhibited the peaks related to optical phonon modes of ZnO in all grown samples with a small shift. Roughly spherical particles anchored on PANI and rGO were confirmed by FE-SEM images. The optical energy bandgap has shifted towards the visible region for grown samples, evident from UV–Visible spectra. PL spectra exhibited lower recombination of charge carriers in rGO and PANI-based catalysts. The photocatalytic degradation experiment against methylene blue (MB) and methyl orange (MO) dyes under solar light demonstrated that rGO anchored catalyst completely degraded both dyes under 40 min solar light irradiation with an observed rate constant 0.1403 min−1, and 0.1402 min−1, respectively, and has higher reusability up to 6th cycle towards MB dye. The enhanced photodegradation efficiency is because of lower recombination of charge carriers in rGO-based composites than others, electron acceptor nature, fast electron mobility, massive surface area, and higher generation of reactive species such as superoxide and hydroxyl radicals (confirmed by scavengers tests). Moreover, the results exhibit the importance of grown catalysts for potential application in wastewater treatment.