Steam reforming of light hydrocarbons provides a promising method for hydrogen production. Ni-based catalysts are so far the best and the most commonly used catalysts for steam reforming because of their acceptably high activity and significantly lower cost in comparison with alternative precious metal-based catalysts. However, nickel catalysts are susceptible to deactivation from the deposition of carbon, even when operating at steam-to-carbon ratios predicted to be thermodynamically outside of the carbon-forming regime. Reactivity and deactivation by carbon formation can be tuned by modifying Ni surfaces with a second metal, such as Au through alloy formation. In the present review, we summarize the very recent progress in the design, synthesis, and characterization of supported bimetallic Ni-based catalysts for steam reforming. The progress in the modification of Ni with noble metals (such as Au and Ag) is discussed in terms of preparation, characterization and pretreatment methods. Moreover, the comparison with the effects of other metals (such as Sn, Cu, Co, Mo, Fe, Gd and B) is addressed. The differences of catalytic activity, thermal stability and carbon species OPEN ACCESSCatalysts 2013, 3 564 between bimetallic and monometallic Ni-based catalysts are also briefly shown.

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Bamboo-like carbon nanotubes are members of the carbon nanotubes (CNTs) family, whose structure is made up of separated hollow compartments and bamboo knots. Due to the peculiar structure of the CNTs species, the growth mechanism and related features have been widely investigated. Bamboo-like carbon nanotubes are widely applied in several fields, such as sensors, adsorbents, catalysts, and lithium-ion battery electrodes materials. Different methods have been applied for the synthesis of carbon nanotubes, among them, catalytic chemical vapor deposition has been singled out as the most used procedure due to low cost with a high quality product. The present review is devoted to increasing the literature dealing with the design, synthesis, and characterization of bamboo-like carbon nanotubes grown over different catalysts. Results on the methane dry reforming reaction, hydrocarbon thermal decomposition, special chemical vapor deposition as well as other methods applied to the preparation of bamboo-like carbon nanotubes are discussed. The differences in the carbon deposits between the dry reforming reaction and other reaction methods are compared and possible formation mechanisms of bamboo-like carbon nanotubes are discussed.

Perovskite oxides La1−xSrxCo1−yFeyO3-δ (LSCF) have been extensively investigated and developed as cathode materials for intermediate temperature solid oxide fuel cells (IT-SOFCs) due to mixed ionic-electronic conductivity and high electrooxygen reduction activity for oxygen reduction. Recent literature investigations show that cathode performances can be improved by metal surface modification or B-site substitution on LSCF. Although the specific reaction mechanism needs to be further investigated, the promoting effect of metal species in enhancing oxygen surface exchange and oxygen bulk diffusion is well recognized. To our knowledge, no previous reviews dealing with the effect of metal promotion on the cathodic performances of LSCF materials have been reported. In the present review, recent progresses on metal (Pd, Pt, Ag, Cu, Zn, Ni) promotion of LSCF are discussed focusing on two main aspects, the different synthesis approaches used (infiltration, deposition, solid state reaction, one pot citrate method) and the effects of metal promotion on structural properties, oxygen vacancies content and cathodic performances. The novelty of the work lies in the fact that the metal promotion at the B-site is discussed in detail, pointing at the effects produced by two different approaches, the LSCF surface modification by the metal or the metal ion substitution at the B-site of the perovskite. Moreover, for the first time in a review article, the importance of the combined effects of oxygen dissociation rate and interfacial oxygen transfer rate between the metal phase and the cathode phase is addressed for OPEN ACCESSCatalysts 2015, 5 367 metal-promoted LSCF and compared with the un-promoted oxides. Perspectives on new research directions are shortly given in the conclusion.