Nitrogen-containing carbon nano-onions-like and graphene-like materials derived from biomass and the adsorption and visible photocatalytic performance

Highlights: • Nano-onions-like and multilayers graphene-like NC materials were prepared derived from biomass. • Fe(NO₃)₃ plays multifunctional roles in the conversion of biomass to NC materials. • Nano-onions structure and graphite N is beneficial to the adsorption and photocatalytic performance. • Superoxide radical is the active species in the photocatalysis of NC material. Nitrogen-containing carbon (NC) materials with different morphologies, nano-onions-like material with size of 20–30 nm and multilayered graphene-like materials with 2–5 layers, were prepared in the aid of Fe(NO₃)₃ through a facile hydrothermal method followed by calcination at low temperature. In the method, the eco-friendly biomass Lentinus edodes was used as carbon nitrogen source, Lentinus edodes isused as carbon-nitrogen source, and Fe(NO₃)₃ is used as nitrogen-fixing agent to fix the nitrogen in the biomass by Fe-N coordination and shape-regulating agent to regulate the morphology of goal materials, thereby catalyzing the conversion of biomass to NC materials. The adsorption and visible-light photocatalytic performance are investigated using phenol as the pollutant. The result shows that the nitrogen content in NC material with nano-onions-like reaches to 5.83%. The pyridinic N can be used as active sites while the hollow nano-onions structure can inhibit the desorption of phenol to improve the adsorption performance. Both unique structure and active site are beneficial to the adsorption ability. The photocatalytic performance shows that the degradation rate of nano-onions-like NC material for phenol reaches to 56.28% under visible-light irradiation, exhibits good visible-light photocatalytic performance than the others. The active species O²⁻ plays important role in the photocatalytic degradation of phenol. And, the graphite N in NC material is helpful to separation of the photoelectrons and holes, enhancing the photocatalytic performance.