Cyanobacterial hydrothermal carbonization carbon as photocatalyst for selective aerobic oxidation of cyclohexane

The exploration of catalyst preparation techniques that incorporate environmental-friendly methodologies has consistently been the focus of scientific inquiry within the field of green synthesis of oxygen-containing organic chemicals. Herein, a metal-free hydrothermal carbonation carbon (HTCC) has been prepared utilizing cyanobacterial biomass produced during a water bloom in a freshwater lake. The HTCC produced is capable of performing photocatalytic selective oxidation of cyclohexane to cyclohexanol and cyclohexanone (KA oil) under ambient conditions. The use of cyanobacterial biomass allows for the efficient preparation of HTCC, which exhibits a conversion rate of cyclohexane that is 4.1 times of HTCC prepared with alternative carbon sources (glucose). The selectivity to KA oil over the samples are almost 100 %. Characterizations and analysis reveal that cyanobacteria can lead to self-doping of nitrogen and hydrophobicity of the resulting HTCC, while sulfuric acid etching endow it with more photoactive sp2 hybridized structure units that contribute to a higher photogenerated carrier separation efficiency. The suitable band structure enables the cyanobacterial HTCC to produce superoxide radicals to oxidize cyclohexane. These findings are of great significance for the development of ecofriendly photocatalysts and the utilization of biomass resources.