Graphene quantum dots with the high edge-to-area ratio have possibly substantial spin polarized edge states, which theoretically can generate fascinating magnetic properties. The magnetism of well-defined graphene quantum dots is relevant with both fundamental physics and potential applications in spintronics. In this article, we report the intrinsic magnetism of graphene quantum dots. Our graphene quantum dots with the average diameter of ca. 2.04 nm show the purely Curie-like paramagnetism with the local moment of 1.2 μ B at 2 K. It is proposed that the magnetic moment of graphene quantum dots may mainly origin from the residual zigzag edges passivated by hydroxyl groups. The ratio of nonmagnetic graphene quantum dots is approximately 6/7, with most of the magnetic edge states suppressed by edge defects and/or edge reconstruction arising from the high-temperature annealing. Our study experimentally unveils the intrinsic magnetism of graphene quantum dots.
We obtain reasonably tight upper and lower bounds on the sum n x ϕ (⌊x/n⌋), involving the Euler functions ϕ and the integer parts ⌊x/n⌋ of the reciprocals of integers.
Atomically
thin two-dimensional (2D) carbon nitride sheets (CNs)
are attracting attention in the field of photocatalytic CO2 reduction. Because of the rapid recombination of photogenerated
electron–hole pairs and limited more active sites, the photocatalytic
efficiency of CNs cannot meet the actual requirements. Here, atomically
thin 2D/2D van der Waals heterostructures of metal-free graphdiyne
(GDY)/CNs are fabricated through a simple electrostatic self-assembly
method. Experimental characterizations along with first-principles
calculations show that the introduction of GDY in CNs promoted the
transport of photogenerated carriers in the melon chain, thus suppressing
the recombination of photogenerated electron–hole pairs. Both in situ FTIR measurements and DFT calculation confirm that
the introduced GDY served as the CO2 adsorption site and
enhanced the CO2 adsorption capacity of the CNs/GDY heterostructure.
Thanks to the 2D/2D van der Waals heterojunction, the optimized CNs/GDY
enhances significantly the CO generation rate up to 95.8 μmol
g–1 that is 19.2-fold higher than that of CNs. This
work provides a viable approach for the design of metal-free van der
Waals heterostructure-based photocatalysts with high catalytic activity.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.