S-doped carbon nanosheets supported ZnO with enhanced visible-light photocatalytic performance for pollutants degradation

Abstract

The exploration of highly efficient and stable visible-light-driven photocatalysts remains a great challenge for organic pollutant management. Herein, a novel S-doped carbon nanosheet (SCN)/ZnO composite photocatalyst has been synthesized via a facile method using the freeze-drying cellulose nanocrystals (CNCs) as the carbon precursor. The surface morphology and chemical environment of SCNs can be regulated simultaneously with S-doping. Compared to the pristine carbonized CNCs (CN), the SCN carbonized at 550 °C (SCN-550) has regular nanosheet-like morphology, integrated graphitic structures (ID/IG of 0.692), rich surface heteroatoms (14.62 at% for O, 1.93 at% for S), and most content of oxidized-S atoms (100 at%). It endows the increased surface reactive sites (specific surface area of 45.55 m2 g−1), accelerated electron transfer, enhanced visible-light absorption, and prolonged carrier lifetime for the corresponding SCN-550/ZnO composite. Consequently, the SCN-550/ZnO shows an outstanding photocatalytic performance for methylene blue (99%). In addition, SCN-550/ZnO composite exhibits general application to organic contaminants, including phenol (91%), formaldehyde (92%), acetone (79%), and methyl alcohol (84%), respectively. Furthermore, the strong interaction of Zn–O–C covalent bond between SCN-550 and ZnO ensures the high photocatalytic activity of SCN-550/ZnO composite after four cycles, demonstrating its excellent reusability and stability. This study develops a highly efficient visible-light photocatalyst of CNCs derived S-doped carbon nanosheets supported ZnO for environment purification.