Fabricating ZnO/lignin-derived flower-like carbon composite with excellent photocatalytic activity and recyclability

The application of ZnO nanoparticles as photocatalyst is significantly hampered by limited absorption range for solar spectrum, fast recombination of photogenerated carriers and poor recyclability. The modification with carbon structures has attracted attention as their advantageous performance in photocatalysis. Herein, we first report a lignin-derived flower-like carbon (LFC), which is used to modify ZnO. The resulting composite (ZnO/LFC) is composed of ZnO nanoparticles (∼10 nm) embedded on a flower-like carbon consisting of two-dimensional corrugated nanosheets. Especially, LFC exhibits stable three-dimensional structure and rich oxygen-containing functional groups. So ZnO can be uniformly anchored on the LFC. Composite presents an extended optical absorption and enhanced separation of photogenerated carriers due to the interface electronic interaction between ZnO and LFC. The hierarchical flower-like structure facilitates fast substance transfer and high light-harvesting efficiency. Therefore, ZnO/LFC presented an excellent photocatalytic activity toward degradation of sulfamethazine and hydrogen evolution, which were about 3.0 and 2.1 times that of pure ZnO, respectively. Moreover, the recyclability of composite photocatalyst was also significantly better than pure ZnO. This work not only provides a facile, low-cost and scalable strategy to promote practical application of photocatalyst but also opens new path toward the high-value utilization of industrial lignin.