Hybrids Of Fullerene C₆₀ And 2D Materials:Synthesis And Applications In Catalysis And Energy Storage

Since the discovery in 1985,fullerene C60 has attracted tremendous attention with extensive study on its molecular and electronic structures,physiochemical properties as well as applications in different fields including energy conversion and storage.Graphene is a special type of two-dimensional carbon materials with high carrier mobility,large specific surface area and high transparency.By hybridizing zero-dimensional(OD)fullerene and two-dimensional(2D)materials such as graphene via covalent bonding or non-convalent interactions,the as-formed 0D/2D hybrid materials would not only combine the properties of both components,but also exhibit better or even more intriguing new properties due to the synergistical interactions between the two components.Although a few fullerene/graphene hybrid materials have been reported in literatures,solution chemistry was typically used,and many problems existed including the perturbation of the ?-conjugated structure of C60 and unavoidable oxidation of graphene.In this dissertation,we focused on developing solid-state mechanochemical methods to construct hybrids of C60 with different 2D materials,without perturbing the ?-conjugated structure of C60 and damaging the basal structure of graphene or graphene-like 2D material,which were applied in catalysis and energy storage,and carried out the following works:1)Using a facile solid-state mechanochemical method by ball milling,we successfully synthesized the first directly bonded graphene-C60 hybrid,for which LiOH is found to play a crucial role as the catalyst.The hybrid structure of graphene-C60 is confirmed by FTIR,Raman,and XPS spectroscopies and XRD characterizations,and its conformation is proposed,featuring the direct bonding of graphene nanoplatelets and C60 via two C-C single bonds.SEM measurement suggests that severe edge distortions occur for graphene-C60 hybrid,and HR-TEM study indicate the covalent attaching of C60 molecules onto the edge of graphene nanoplatelets,in consistent with the spectroscopic results.Finally,we applied the graphene-C60 hybrid as a carbon-based electrocatalyst toward oxygen reduction reaction(ORR),showing improved ORR electrocatalytic activity than the pristine graphite and C60.2)We first synthesized a zeolitic imidazolate framework-8(ZIF-8)precursor embedding C60 via solid-state mechanochemical method by ball milling,which was transformed to a novel C60-embedded nitrogen-doped microporous carbon material(denoted as C60@N-MPC)after one-step carbonization.We then applied C60@N-MPC as a novel anode for Lithium Ion Batterys(LIBs),showing an improved reversible specific capacity of ?1351 mAh g-1 at 0.1 A g-1 and rate capacity(?1077 mAh g-1 at 1 A g-1 after 400 cycles)relative to those based on the unmodified N-MPC anode.The role of C60 on the superior lithium storage performance of C60@N-MPC was elucidated,revealing that C60 functioned as a pore expander for N-MPC with 3-20 nm mesopores(versus sub-1 nm micropores for the unmodified N-MPC),which facilitated the rapid diffusion of organic electrolyte.3)As a representative graphene-like inorganic 2D material,molybdenum disulfide(MoS2)has been extensively used as a noble-metal-free cocatalyst for photocatalytic hydrogen(H2)production,but suffers from poor photocatalytic activity.We propose to bound C60 onto MOS2 nanosheets so as to improve the photocatalytic activity of MoS2,and successfully prepared a MOS2-C60 hybrid via a facile and eco-friendly solid-state mechanochemical route.Based on a series of spectroscopic characterizations,we proposed that MoS2-C60 hybrid likely takes a van der Waals heterostructure.After bounding C60 onto the edge of MoS2 nanosheets,both the number of layers and the size of MoS2 nanosheets are dramatically decreased,and both conduction band and valance band energy levels are shifted.As a result,under the optimized weight ratio of MOS2:C60(1:1)in the raw mixture subject to ball-milling,MoS2-C60 hybrid shows a visible light photocatalytic H2 production rate of 6.89 mmol h-1 g-1,which is significantly enhanced relative to those of the bulk MoS2 and pristine C60,both of which show almost no photocatalytic H2 activity.Thus,the synergistic enhancement of photocatalytic activities of both MoS2 and C60 is revealed.