Direct Synthesis of Exfoliated Carbon Nitride Mediated by Sodiated Cellulose Nanocrystals for Photocatalytic and Adsorbent Applications

As an evolving 2D organic semiconductor, graphitic carbon nitride has drawn scientific research interest for applications extending from photo/electrocatalysis to adsorbents and biosensing. Herein, a few atomic-layer-thick carbon nitride nanosheets (CNNS) were synthesized using an in situ exfoliation technique by introducing sodiated sulfate hydrolyzed cellulose nanocrystals into the polymerization precursor mixture. The directly exfoliated CNNS possessed a much higher concentration of unpaired electron spins than bulk carbon nitride (BCN), as evidenced by EPR spectroscopy. Solid-state NMR, and XPS confirmed the incorporation of sodium in the carbon nitride framework. Introducing Na dopants inhibited the stacking and aggregation of carbon nitride nanosheets, widening the bandgap of a material. When compared to BCN, it was discovered that the bandgap of the exfoliated carbon nitride (NaCNC-CNNS) increased from 2.76 to 2.90 eV, along with a fourfold increase in specific surface area and tenfold increase in pore volume. NaCNC-CNNS exhibited a significant advantage in photogenerated charge carrier separation and transfer compared to BCN. Given its higher PEC water splitting performance and higher aqueous dye adsorption efficiency, the NaCNC-CNNS structure appears to be more suitable as a photoelectrocatalyst and adsorbent than BCN. Molecular dynamics simulations and analyses confirmed that the NaCNC-CNNS structure is more exposed, which facilitates the interaction of solvent molecules with nanosheets and promotes their intercalating action.