Catalyst-free one step synthesis of large area vertically stacked N-doped graphene-boron nitride heterostructures from biomass source

Abstract

A procedure for the one-step preparation of films of few-layer N-doped graphene on top of nanometric hexagonal boron nitride sheets ((N)graphene/h-BN) based on the pyrolysis at 900 °C under an inert atmosphere of a film of chitosan containing about 20 wt% of ammonium borate salt as a precursor is reported. During the pyrolysis a spontaneous segregation of (N)graphene and boron nitride layers takes place. The films were characterized by optical microscopy that shows a thin graphene overlayer covering the boron nitride layer, the latter showing characteristic cracks, and by XPS measurements at different monitoring angles from 0° to 50° where an increase in the proportion of C vs. B and N was observed. The resulting (N)graphene/h-BN films were also characterized by Raman, HRTEM, SEM, FIB-SEM and AFM. The thickness of the (N)graphene and h-BN layers can be controlled by varying the concentration of precursors and the spin coating rate and is typically below 5 nm. Electrical conductivity measurements using microelectrodes can cause the burning of the graphene layer at high intensities, while lower intensities show that (N)graphene/h-BN films behave as capacitors in the range of positive voltages.

Photocatalytic Overall Water Splitting Activity of Templateless Structured Graphitic Nanoparticles Obtained from Cyclodextrins

“…Metal-free catalysis is currently being explored as a possible alternative to the prevalence in heterogeneous catalysis of noble and critical metals with limited resources. − Particularly, metal-free catalysts based on carbon can be considered as sustainable materials when they are obtained from biomass, , although the presence of metallic contaminants and their contribution to the photocatalytic activity must be carefully examined to convincingly assess a truly metal-free nature to these photocatalysts . Besides conventional thermal catalysis, photocatalysis is nowadays attracting considerable attention in the context of utilization of natural sunlight as primary energy source for the production of renewable fuels and chemicals …”

Templateless Synthesis of Ultra‐Microporous 3D Graphitic Carbon from Cyclodextrins and Their Use as Selective Catalyst for Oxygen Activation

“…[7,10,11] It has been typically found that the morphology of the precursor particles is maintained during the pyrolysis step, although particle dimensions shrink, even more than a half, due to the restructuring of the intermolecular distances and occurrence of π-π stacking. [12] Continuing with this line of research, it would be of interest to determine if other saccharides with peculiar morphology can also become transformed into some sort of graphitic carbon and what are the structure and properties of the resulting material.…”

Design, Fabrication, and Mechanism of Nitrogen‐Doped Graphene‐Based Photocatalyst

“…In particular, the synthesis of NG by biomass pyrolysis has been frequently reported and is expected to be applied to the large‐scale production. [ 109–112 ] For instance, Primo et al. [ 113 ] synthesized high‐quality monolayer NG by the pyrolysis of biomass waste (chitosan) at 800 °C.…”