Nanocrystal Growth on Graphene with Various Degrees of Oxidation

Abstract

As a single-atom thick carbon material with light-weight, high surface area and conductivity, graphene 1,2 could be ideal substrates for growing and anchoring of functional nanomaterials for high performance electrocatalytic or electrochemical devices. Nanocrystals grown on graphene could have enhanced electron transport rate, high electrolyte contact area and structural stability, all of which could be useful for various fundamental and practical applications. 3 Although decoration of nanoparticles on graphite oxide (GO) sheets has been shown, 4-6 it remains unexplored and highly desirable to synthesize nanocrystals on more pristine graphene with high electrical conductivity, control the morphologies of the nanocrystals by tuning the oxidation degrees of the graphene sheets, and rationalize the nanocrystal growth behavior.Here, we show a general two-step method to grow hydroxide and oxide nanocrystals of the iron family elements (Ni, Co, Fe) on graphene with two degrees of oxidation. Drastically different nanocrystal growth behaviors were observed on low-oxidation graphene sheets (GS) and highly oxidized GO in hydrothermal reactions. Small particles pre-coated on GS with few oxygen-containing surface groups diffused and recrystallized into single-crystalline nanoplates or nanorods with well defined shapes. In contrast, particles pre-coated on GO were pinned by the high-concentration oxygen groups and defects on GO without recrystallization into well-defined morphologies. Our results suggest an interesting approach to controlling the morphology of nanocrystals by tuning the surface chemistry of graphene substrates used for crystal nucleation and growth.Our GS with low degree of oxidation were made by an exfoliation-reintercalation-expansion method, 7-9 and GO was produced by a modified Hummers method 10 (Figure 1). The resistivity of our

Control of size and physical properties of graphene oxide by changing the oxidation temperature

“…of the graphene oxide substrate [18][19][20]. Therefore, control of graphite oxidation is necessary for various applications of graphene oxide sheets.…”

Review of Electrochemical Capacitors Based on Carbon Nanotubes and Graphene

“…So far, the various carbon-based materials, including activated carbon, ordered mesoporous carbon, carbon nanotubes (CNT), graphene and their composites, are intensively utilized for the fabrication of EC. Among these nanomaterials, CNT and graphene are the rising nanomaterials for electronic and energy storage devices due to their highly accessible surface area, nanoscale structure and good electrical conductivity since they were discovered [13][14][15]. Thus the primary focus in this paper will be on the recently developed progresses of EC based on CNT, graphene and their composite in laboratory and industry.…”

Constructing monodispersed MoSe2 anchored on graphene: a superior nanomaterial for sodium storage

“…S1e), demonstrating the rGO nanosheets are good substrates for the growth of MoSe2 nanosheets. The selective growth of MoSe2 nanostructures on rGO was possibly attributed to the precursors anchored on the surface of GO with functional groups (carboxyl and hydroxyl) [23][24][25]. While in the absence of GO, the as-formed MoSe2 are connected with each other (Fig.…”