Few-layered mesoporous graphitic carbon nitride: a graphene analogue with high capacitance properties

Abstract

Two-dimensional nanomaterials have attracted considerable attention owing to their promising applications in various fields. Herein, we report the synthesis and capacitance properties of few-layered mesoporous graphitic carbon nitride (MGCN-E). MGCN-E, a graphene analogue, is synthesized by thermal exfoliation of multi-layered mesoporous graphitic carbon nitride (MGCN) in air. Sorption studies reveal that the surface area, number of mesopores and pore volume increase on thermal exfoliation of multi-layered MGCN and microscopic studies provide direct evidence for the formation of few-layered MGCN. A graphene-like MGCN with higher surface area, more mesopores, larger pore volume and higher relative percentage of pyridinic nitrogen and carbonyl oxygen delivers higher specific capacitance than multi-layered MGCN at all current rates. Also, MGCN-E outperforms several N-doped graphenes and composites of graphitic carbon nitride. Owing to higher contribution from the pseudocapacitance, the rate performance of MGCN-E is slightly compromised (MGCN and MGCN-E retain 52 and 49.66% of their initial specific capacitance when the current density is increased from 0.5 to 20 A g⁻¹, respectively). Both MGCN and MGCN-E exhibit excellent cycling stability over 10 000 cycles. This study demonstrates that the textural and capacitance properties of MGCN can be improved by thermal exfoliation.