Facile preparation of well-combined lignin-based carbon/ZnO hybrid composite with excellent photocatalytic activity

Highlights: • 1 The LC/ZnO hybrid was synthesized using industrial lignin by a simple carbonization method. • 2 The LC/ZnO hybrid is composed of ZnO nanoparticles and carbon nanosheets. • 3 The LC/ZnO hybrid exhibited excellent surface contact and photocatalytic performance. • 4 The LC/ZnO hybrid showed photocatalytic mechanism for the different charged dyes. - Abstract: In this work, a novel lignin-based carbon/ZnO (LC/ZnO) hybrid composite with excellent photocatalytic performance was prepared through a convenient and environment friendly method using alkali lignin (AL) as carbon source. The morphological, microstructure and optical properties of the as-prepared LC/ZnO hybrid composite was characterized with scanning electron microscope (SEM), X-ray diffraction (XRD), Raman and UV–vis. The resulting LC/ZnO hybrid is composed of highly dispersed ZnO nanoparticles embedded on a lignin-based carbon nanosheet, showing excellent photogenerated electrons and holes separation and migration efficiency. The photocatalytic activity of LC/ZnO was much higher than the pure ZnO. The LC/ZnO hybrid composite showed different photocatalytic mechanism for degradation of negative methyl orange (MO) and positive Rhodamine B (RhB). It showed that h⁺ was the main photocatalytic active group during the degradation of MO, ·O₂⁻ and ·OH were the photocatalytic active groups during degradation of RhB. This reported photocatalyst with selective degradation of positive and negative organic dyes may have a great application prospect for photoelectric conversion and catalytic materials. Results of this work were of practical importance for high-valued utilization of lignin for carbon materials.