CeO2/rGO/Pt sandwich nanostructure: rGO-enhanced electron transmission between metal oxide and metal nanoparticles for anodic methanol oxidation of direct methanol fuel cells.
ABSTRACT Pt-based nanocomposites have been of great research interest. In this paper, we design an efficient MO/rGO/Pt sandwich nanostructure as an anodic electrocatalyst for DMFCs with combination of the merits of rigid structure of metallic oxides (MOs) and excellent electronic conductivity of reduced oxidized graphene (rGO) as well as overcoming their shortcomings. In this case, the CeO(2)/rGO/Pt sandwich nanostructure is successfully fabricated through a facile hydrothermal approach in the presence of graphene oxide and CeO(2) nanoparticles. This structure has a unique building architecture where rGO wraps up the CeO(2) nanoparticles and Pt nanoparticles are homogeneously dispersed on the surface of rGO. This novel structure endows this material with great electrocatalytic performance in methanol oxidation: it reduces the overpotential of methanol oxidation significantly and its electrocatalytic activity and stability are much enhanced compared with Pt/rGO, CeO(2)/Pt and Pt/C catalysts. This work supplies a unique MO/rGO/Pt sandwich nanostructure as an efficient way to improve the electrocatalytic performance, which will surely shed some light on the exploration of some novel structures of electrocatalyst for DMFCs.
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ABSTRACT: Through direct nanoparticle nucleation and growth on nitrogen doped, reduced graphene oxide sheets and cation substitution of spinel Co(3)O(4) nanoparticles, a manganese-cobalt spinel MnCo(2)O(4)/graphene hybrid was developed as a highly efficient electrocatalyst for oxygen reduction reaction (ORR) in alkaline conditions. Electrochemical and X-ray near-edge structure (XANES) investigations revealed that the nucleation and growth method for forming inorganic-nanocarbon hybrids results in covalent coupling between spinel oxide nanoparticles and N-doped reduced graphene oxide (N-rmGO) sheets. Carbon K-edge and nitrogen K-edge XANES showed strongly perturbed C-O and C-N bonding in the N-rmGO sheet, suggesting the formation of C-O-metal and C-N-metal bonds between N-doped graphene oxide and spinel oxide nanoparticles. Co L-edge and Mn L-edge XANES suggested substitution of Co(3+) sites by Mn(3+), which increased the activity of the catalytic sites in the hybrid materials, further boosting the ORR activity compared with the pure cobalt oxide hybrid. The covalently bonded hybrid afforded much greater activity and durability than the physical mixture of nanoparticles and carbon materials including N-rmGO. At the same mass loading, the MnCo(2)O(4)/N-graphene hybrid can outperform Pt/C in ORR current density at medium overpotentials with stability superior to Pt/C in alkaline solutions.Journal of the American Chemical Society 02/2012; 134(7):3517-23. · 10.68 Impact Factor
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ABSTRACT: We report the formation of a new PtRuIr catalyst using an organic colloid synthesis method, involving acetone as the solvent, ethylene glycol as the reducing agent, citrate as a complexing agent and stabilizer, and multiwall carbon nanotubes (CNT, diameter 8-10 nm) as the support. This catalyst has a very high real surface area and is highly active toward the oxidation of methanol, relevant to fuel cell applications. The Ir component appears to act as a promoter, and the splitting of the Pt(111) XRD feature into four peaks and the shift to larger d spacing reflect the high dispersion of the metallic components.Journal of the American Chemical Society 04/2006; 128(11):3504-5. · 10.68 Impact Factor
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ABSTRACT: We developed a facile strategy for clean synthesis of Pt/CeO(2)/graphene nanomaterials with remarkably enhanced catalytic properties. The graphene oxide (GO) could be used as an oxidant to oxidize Ce(3+) into CeO(2) NPs, and l-lysine was used as a linker to realize the in situ growth of Pt NPs around CeO(2) NPs dispersed on graphene.Chemical Communications 03/2012; 48(23):2885-7. · 6.38 Impact Factor