Efficient anchorage of Pd nanoparticles on carbon nanotubes as a catalyst for hydrazine oxidation

A simple method is devised to deposit well-dispersed Pd nanoparticles on multi-walled carbon nanotubes (CNTs). Pd nanoparticles (1–3 nm) prepared in ethanol were transferred to toluene solution and modified by organic molecule benzyl mercaptan which acts as a cross linker between Pd nanoparticles and CNTs. The morphology and structure of the resulting Pd/CNT nanocomposite were characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The results show that Pd nanoparticles were highly dispersed and effectively anchored on CNTs. The excellent electrocatalytic activity of the Pd/CNT nanocomposite for the oxidation of hydrazine was demonstrated by cyclic voltammetry.     

Graphene nanoplatelets supported metal nanoparticles for electrochemical oxidation of hydrazine

Graphene nanoplatelets have been applied as the support to electrodeposit monometallic Au and Pd nanoparticles as well as bimetallic Au–Pd nanoparticles. These nanoparticles have been characterized with scanning electron microscope, energy dispersive X-ray spectroscopy, X-ray diffraction spectroscopy, and electrochemical techniques. They are further utilized as the catalysts for electrochemical oxidation of hydrazine. The oxidation peak potential is − 0.35 and 0.53 V (vs. SCE) when monometallic Pd and Au nanoparticle are used as the catalysts. When bimetallic nanoparticles are applied as the catalyst, their composition affects the peak potential and peak current for the oxidation of hydrazine. Higher oxidation current is achieved when bimetallic Au–Pd nanoparticles with an atomic ratio of 3:1 are deposited on graphene nanoplatelets. Metal nanoparticle-loaded graphene nanoplatelets are thus novel platforms for electrocatalytic, electroanalytical, environmental, and related applications.     

Au-Cu Alloy nanoparticles confined in SBA-15 as a highly efficient catalyst for CO oxidation

Au-Cu Alloy nanoparticles with sizes of approximately 3 nm were prepared in the confined space of SBA-15 and showed much better performance than monometallic particles in catalyzing CO oxidation even with the rich presence of H(2).     

Pd nanoparticles as catalysts for green and sustainable oxidation of functionalized alcohols in aqueous media

The previously described catalyst system for the aerobic oxidation of alcohols, comprising palladium(II) acetate in combination with neocuproine in a 1:1 mixture of water and a water-miscible cosolvent such as ethylene carbonate or dimethylsulfoxide, was shown to involve palladium nanoparticles as the active catalyst. The latter are formed in situ or can be preformed by reduction of the palladium-neocuproine complex with hydrogen and they are stabilized by both the neocuproine ligand and the cosolvent. This catalyst system was successfully used for the selective aerobic oxidation of the steroidal secondary alcohols, nandrolone and 5α-pregnan-3α-ol-20-one, to the corresponding ketones.     

Hydroxylated surface of GaAs as a scaffold for a heterogeneous Pd catalyst

A novel use of GaAs, namely, as a scaffold for a heterogeneous palladium catalyst, is proposed. Hydroxy groups on the GaAs surface play important roles. During the adsorption of Pd(OAc)(2) on the GaAs surface, the hydroxy groups attract Pd(ii) species by anion exchange. A subsequent redox reaction proceeds to generate Pd(0) nanoparticles, which are stabilized on the GaAs surface. This process is confirmed by surface-sensitive measurements: diffuse reflection IR spectroscopy and X-ray photoelectron spectroscopy. Moreover, a more bulk-sensitive measurement, hard X-ray photoemission spectroscopy with synchrotron radiation, also supported our considerations. The amounts of Pd(0) nanoparticles on the surface were evaluated by catalytic activity, yield, and recyclability in the Heck reaction, in addition to the deposit test.     

Surfactant-modified polypropylene as a catalyst for oxidation of mercaptans

Surface modification of polypropylene by soluble metallophthalocyanine was performed. The effect of pretreatment of polypropylene on the degree of surface anchoring of the macrocycle was shown. The catalytic activity of the hybrid materials produced in the oxidation reaction of sodium diethyldithiocarbamate was determined.     

Diatomite-supported Pd nanoparticles: an efficient catalyst for Heck and Suzuki reactions

The Pd nanoparticles immobilized on natural diatomite were achieved by a simple procedure. The catalysts are highly active for Heck and Suzuki reactions and can be recovered and reused many times. The catalytic process was also investigated.     

Pd on amine-terminated ferrite nanoparticles: a complete magnetically recoverable facile catalyst for hydrogenation reactions

[structure: see text]. The present communication reports a facile route for Pd(0) immobilization on the surface of amine-terminated Fe3O4 and NiFe2O4 nanoparticles for a series of hydrogenation reactions. The catalysts are completely recoverable with the simple application of an external magnetic field, and the efficiency of the catalyst remains unaltered even after 10 repeated cycles for each of the reactions.     

Preparation of Pd/C catalyst for formic acid oxidation using a novel colloid method

A novel colloid method using (WO₃)_n·xH₂O as colloidal source was developed to prepare Pd/C catalyst for formic acid oxidation. Transmission electron microscopy image shows that the Pd/C nanoparticles have an average size of 3.3 nm and a narrow size distribution. Electrochemical measurements indicate that the Pd/C catalyst exhibits significantly high electrochemical active surface area and high catalytic activity with good stability for formic acid oxidation compared with that prepared by common method. The colloid method is very simple and has great potentials for mass-producing Pd/C and others noble metal catalysts.     

Formation and oxidation mechanisms of Pd-Zn nanoparticles on a ZnO supported Pd catalyst studied by in situ time-resolved QXAFS and DXAFS

Formation and oxidation processes of PdZn nanoparticles on ZnO were successfully observed by means of in situ time-resolved X-ray absorption fine structure spectroscopy (XAFS), and the analysis of data on near-edge (XANES) and extended (EXAFS) structures revealed detailed changes in Pd during both processes. PdZn nanoparticles were formed on ZnO through a two-step scheme under a hydrogen atmosphere. The first process was the formation of metallic Pd nanoparticles, which was quickly finished within 1 s. The second process was the formation of PdZn nanoparticles, which took several tens of minutes. Oxidation of the PdZn nanoparticles also consisted of two processes. Zn atoms were oxidized prior to Pd atoms and the metallic Pd nanoparticles surrounded by ZnO were formed afterwards. Oxidation of the metallic Pd nanoparticles was scarce and very slow. According to the results of kinetic analyses, the metallic Pd surrounded by ZnO was a stable species under the oxidative atmosphere.     

Pd nanoparticles supported on CeO2 as efficient catalyst for hydrogen generation from formaldehyde solution at room temperature

A facile and efficient method for facilitating hydrogen generation from formaldehyde aqueous solution was developed using Pd nanoparticles supported on CeO₂ (Pd/CeO₂) as the catalyst. The prepared Pd/CeO₂ catalyst exhibited 100% H₂ selectivity and excellent catalytic activity for formaldehyde dehydrogenation with the initial rate of 2089 ml min⁻¹ g_Pd⁻¹ at room temperature and atmospheric pressure without any extra additive. The prepared catalyst was stable and reusable, and its catalytic activity kept almost unchanged after it was reused for the fifth run. Therefore, it is considered that this Pd/CeO₂ based hydrogen generation system may serve as an alternative hydrogen supply candidate for practical application.     

CoSALEN as a new catalyst for oxidation of fullerene C60

The effect of CoSALEN on anti-oxidative properties of fullerene C₆₀ in the presence of O₂ in cumene was investigated. A comparison was made between the role of the CoSALEN as a catalyst in the C₆₀ oxidation and oxidation in the presence of an initiator, i.e., AIBN. A mechanism is proposed for the catalytic role of CoSALEN in oxidation of C₆₀. Oxidation of octadecylaminofullerene C₆₀ at the same conditions reveals that oxidation could be a result of hydroperoxidation of the unreacted sites of C₆₀. We conclude that C₆₀ as well as its amino-derivatives enhance the efficiency of CoSALEN in the oxidation of cumene due to their radical scavenging property of their unreacted double-bond sites.     

Pd nanoparticles supported on amphiphilic porous organic polymer as an efficient catalyst for aqueous hydrodechlorination and Suzuki-Miyaura coupling reactions

Developing efficient and recyclable heterogeneous catalysts for organic reactions in water is important for the sustainable development of chemical industry. In this work, Pd nanoparticles supported on DABCO-functionalized porous organic polymer was successfully prepared through an easy copolymerization and successive immobilization method. Characterization results indicated that the prepared catalyst featured big surface area, hierarchical porous structure, and excellent surface amphiphilicity. We demonstrated the use of this amphiphilic catalyst in two case reactions, i.e. the aqueous hydrodechlorination and Suzuki-Miyaura coupling reactions. Under mild reaction conditions, the catalyst showed high catalytic activities for the two reactions. In addition, the catalyst could be easily recovered and reused for several times. Also, no obvious Pd leaching and aggregation of Pd nanoparticles occurred up during the consecutive reactions.     

New carbon nanofiber/graphite felt composite for use as a catalyst support for hydrazine catalytic decomposition

Graphite felt supporting 40 nm diameter carbon nanofibers was synthesized and successfully used as a support for a high loaded iridium catalyst (30 wt%) in the decomposition of hydrazine; a strong mechanical resistance and a high thermal conductivity led to a very efficient and stable catalyst as compared to that used industrially, iridium supported on a high surface area alumina.