Guoqiang Jin

Cuprous oxide nanoparticles dispersed on reduced graphene oxide as an efficient electrocatalyst for oxygen reduction reaction

Cuprous oxide (Cu(2)O) nanoparticles dispersed on reduced graphene oxide (RGO) were prepared by reducing copper acetate supported on graphite oxide using diethylene glycol as both solvent and reducing agent. The Cu(2)O/RGO composite exhibits excellent catalytic activity and remarkable tolerance to methanol and CO in the oxygen reduction reaction.

Copper nanoparticles on graphene support: an efficient photocatalyst for coupling of nitroaromatics in visible light.

Copper is a low-cost plasmonic metal. Efficient photocatalysts of copper nanoparticles on graphene support are successfully developed for controllably catalyzing the coupling reactions of aromatic nitro compounds to the corresponding azoxy or azo compounds under visible-light irradiation. The coupling of nitrobenzene produces azoxybenzene with a yield of 90 % at 60 °C, but azobenzene with a yield of 96 % at 90 °C. When irradiated with natural sunlight (mean light intensity of 0.044 W cm(-2) ) at about 35 °C, 70 % of the nitrobenzene is converted and 57 % of the product is azobenzene. The electrons of the copper nanoparticles gain the energy of the incident light through a localized surface plasmon resonance effect and photoexcitation of the bound electrons. The excited energetic electrons at the surface of the copper nanoparticles facilitate the cleavage of the NO bonds in the aromatic nitro compounds. Hence, the catalyzed coupling reaction can proceed under light irradiation and moderate conditions. This study provides a green photocatalytic route for the production of azo compounds and highlights a potential application for graphene.

Beaded silicon carbide nanochains via carbothermal reduction of carbonaceous silica xerogel

Novel silicon carbide nanostructures, beaded nanochains, are prepared from the carbothermal reduction of a carbonaceous silica xerogel with cetyltrimethylammonium bromide and lanthanum nitrate as additives. The nanochains consist of a stem with a diameter of about 50 nm and uniform beads with diameters of 100–200 nm. It is demonstrated that the tensile strength of an epoxy composite filled with the SiC nanochains improves significantly due to the unusual morphology of the nanochains.

High photoelectrocatalytic performance of a MoS2–SiC hybrid structure for hydrogen evolution reaction

A flower-like MoS2–SiC hybrid structure assembled from folded MoS2–SiC nanosheets can activate hydrogen evolution at a very low overpotential (0.04 V) and produce a large cathodic current, which compares favorably with that produced by a commercial 20 wt% Pt/C catalyst.

CNT–Ni/SiC hierarchical nanostructures: preparation and their application in electrocatalytic oxidation of methanol

CNT–Ni/SiC composites with three-dimensional hierarchical nanostructures were fabricated via in situ pyrolysis of methane to grow CNTs on a novel flake-like NiO/SiC material. The NiO/SiC was prepared by hydrothermally growing Ni(OH)2 on SiC. After calcination, Ni(OH)2 was converted to porous NiO flakes. During the methane pyrolysis, NiO was in situ converted to Ni nanoparticles, which acted as the catalyst for growing CNTs. Due to the combination of Ni nanoparticles, in situ grown CNTs and the SiC support, the CNT–Ni/SiC composites exhibit excellent catalytic activity and stability in electro-oxidation of methanol. The catalytic activity shows a dependence on the pyrolysis temperature of methane, and a pyrolysis temperature of 700 °C can lead to a mass activity of 10 A mg−1 Ni, which is about 15 times higher than that of the catalyst obtained from methane pyrolysis at 500 °C and about 4000 times higher than that of the original NiO/SiC catalyst.

Visible light-induced selective photocatalytic aerobic oxidation of amines into imines on Cu/graphene

Graphene can stabilize metallic copper nanoparticles and enable them to exhibit excellent photocatalytic activity for aerobic oxidation of various primary and secondary amines into the corresponding imines. The copper nanoparticles stabilized on graphene absorb the energy of visible light via localized surface plasmon resonance, and produce energetic hot electrons that activate the reactants adsorbed on the surface of copper nanoparticles. The formation of imines involves selective oxygenation of amines to aldehydes and subsequent condensation with amines to form imines.

Avoiding Loss of Catalytic Activity of Pd Nanoparticles Partially Embedded in Nanoditches in SiC Nanowires

Nanoditches from selective etching of periodically twinned SiC nanowires were employed to hinder the migration and coalescence of Pd nanoparticles supported on the nanowires, and thus to improve their catalytic stability for total combustion of methane. The results show that the etched Pd/SiC catalyst can keep the methane conversion of almost 100% while the unetched one has an obvious decline in the catalytic activity from 100 to 82% after ten repeated reaction cycles. The excellent catalytic stability originates from the limitation of the nanoditches to the migration and growth of Pd nanoparticles.

Graphene-supported Cu2O nanoparticles: an efficient heterogeneous catalyst for C–O cross-coupling of aryl iodides with phenols

Cu2O/graphene as a heterogeneous catalyst can effectively ignite and catalyze the Ullmann C–O cross-coupling of aryl iodides with phenols under mild conditions. The yield of diphenyl ether from the cross-coupling of phenol and iodobenzene can reach up to 96% at 150 °C in 3 h, and the turnover frequency can be as high as 1282 h−1. Meanwhile, the catalyst exhibits activity for varieties of C–O cross-coupling of aryl iodides, bromides and chlorides with phenol derivatives to form the corresponding aryl ethers.

The enhanced catalytic performance of Pd/SiC for the hydrogenation of furan derivatives at ambient temperature under visible light irradiation

By using semiconductive SiC as the support, palladium exhibits a tremendous promotion of its intrinsic catalytic activity for the hydrogenation of furan derivatives at ambient temperature under visible light irradiation. The promotion in the catalytic activity results from the fact that the Mott–Schottky contact between SiC and Pd enhances the quick transfer of the photo-generated electrons from SiC to Pd nanoparticles.

Structural Changes in Carbon Produced by a sulfur-aided Catalytic Chemical Vapor Deposition

Branched carbon structures were formed by a chemical vapor deposition of toluene using ferrocene as a catalyst precursor and thiophene as a promoter. The effects of sulfur on the carbon products were investigated by SEM, XRD, and EDX. Results show that the product microstructure changes from tree-like to worm-like when the thiophene volume fraction in the toluene increases from 0.01 to 1%. The carbon trees consist of long, straight, and well-developed branches, while the worm carbons are composed of short and curled fibers. There is no obvious difference in d002, La and Lc for the two products.