Electrochemical‐Reduction‐Assisted Assembly of a Polyoxometalate/Graphene Nanocomposite and Its Enhanced Lithium‐Storage Performance

Abstract

Herein, we present an electrochemically assisted method for the reduction of graphene oxide (GO) and the assembly of polyoxometalate clusters on the reduced GO (rGO) nanosheets for the preparation of nanocomposites. In this method, the Keggin-type H4 SiW12O40 (SiW12) is used as an electrocatalyst. During the reduction process, SiW12 transfers the electrons from the electrode to GO, leading to a deep reduction of GO in which the content of oxygen-containing groups is decreased to around 5%. Meanwhile, the strong adsorption effect between the SiW12 clusters and rGO nanosheets induces the spontaneous assembly of SiW12 on rGO in a uniformly dispersed state, forming a porous, powder-type nanocomposite. More importantly, the nanocomposite shows an enhanced capacity of 275 mAh g(-1) as a cathode active material for lithium storage, which is 1.7 times that of the pure SiW12. This enhancement is attributed to the synergistic effect of the conductive rGO support and the well-dispersed state of the SiW12 clusters, which facilitate the electron transfer and lithium-ion diffusion, respectively. Considering the facile, mild, and environmentally benign features of this method, it is reasonable as a general route for the incorporation of more types of functional polyoxometalates onto graphene matrices; this may allow the creation of nanocomposites for versatile applications, for example, in the fields of catalysis, electronics, and energy storage.

Polyoxometalate‐coupled Graphene via Polymeric Ionic Liquid Linker for Supercapacitors

“…However, the entrapping of POMs into polymer matrices inevitably limits the available redox active sites of the POMs, which can constrain their intrinsic capacitances (e.g., 120 F g −1 for POM/polyaniline [ 20 ] and 210 F g −1 for POM/polypyrrole). [25][26][27] Although the combination of POM and graphene can increase the electrical conductivity and provide large available active sites, previously reported approaches have diffi culties related to the strong integration between POMs and graphene as well as the control of the density and position of POMs. More recently, graphene with its large surface area and high electrical conductivity has been newly proposed as a support for anchoring POMs.…”

Facile Electrodeposition of Flower-Like PMo12-Pt/rGO Composite with Enhanced Electrocatalytic Activity towards Methanol Oxidation

“…It may be as a result of the interaction among rGO, PMo12 and Pt. There are no distinct diffraction peaks of PMo12, which may be due to the characteristic diffraction pattern of crystalline PMo12 being absent, which further implies that PMo12 clusters do not exist in the crystalline state but in the dispersed state [17]. The presence of Pt, P, Mo, C, N, and O elements on the surface of the composite is confirmed in the full-spectra of X-ray photoelectron spectroscopy (XPS) (Figure 3a).…”

Polyoxometalate-assisted fabrication of the Pd nanoparticle/reduced graphene oxide nanocomposite with enhanced methanol-tolerance for the oxygen reduction reaction

“…However, there are no noticeable diffraction peaks of PMo12, implying that PMo12 do not exist in the crystalline state, but in the dispersed state with no agglomeration 12. Fig.…”

“…Fig. S1b (ESI †) reveals that the N 2 adsorption-desorption isotherms and corresponding pore size distributions of Pd/PMo12/rGO, and PMo12/rGO, which are of type IV with distinct hysteresis loops, implying a micro/mesoporous structure.suggesting that the successful introduction of POMs breaks the face-to-face stacking of rGO nanosheets 12,15. Nevertheless, because the pores of PMo12/rGO are occupied by Pd NPs, the surface area…”