The energetic convenience of electrolytic water splitting is limited by thermodynamics. Consequently, significant levels of hydrogen production can only be obtained with an electrical energy consumption exceeding 45 kWh kg À 1 H 2 . Electrochemical reforming allows the overcoming of such thermodynamic limitations by replacing oxygen evolution with the oxidation of biomass-derived alcohols. Here we show that the use of an original anode material consisting of palladium nanoparticles deposited on to a three-dimensional architecture of titania nanotubes allows electrical energy savings up to 26.5 kWh kg À 1 H 2 as compared with proton electrolyte membrane water electrolysis. A net energy analysis shows that for bio-ethanol with energy return of the invested energy larger than 5.1 (for example, cellulose), the electrochemical reforming energy balance is advantageous over proton electrolyte membrane water electrolysis.

The new water soluble ruthenium complexes [(C5R5)RuCl(PTA)2] (R = H, Me; PTA = 1,3,5-triaza-7-phosphaadamantane) were synthesised and characterised. Their evaluation as regioselective catalysts for hydrogenation of unsaturated ketones in aqueous biphasic conditions and as cytotoxic agents towards the TS/A adenocarcinoma cell line is briefly presented.

Ni-Zn and Ni-Zn-P alloys supported on Vulcan XC-72 are effective materials for the spontaneous deposition of palladium through redox transmetalation with Pd(IV) salts. The materials obtained, Pd-(Ni-Zn)/C and Pd-(Ni-Zn-P)/C, have been characterized by a variety of techniques. The analytical and spectroscopic data show that the surface of Pd-(Ni-Zn)/C and Pd-(Ni-Zn-P)/C contain very small, highly dispersed, and highly crystalline palladium clusters as well as single palladium sites, likely stabilized by interaction with oxygen atoms from Ni--O moieties. As a reference material, a nanostructured Pd/C material was prepared by reduction of an aqueous solution of PdCl(2)/HCl with ethylene glycol in the presence of Vulcan XC-72. In Pd/C, the Pd particles are larger, less dispersed, and much less crystalline. Glassy carbon electrodes coated with the Pd-(Ni-Zn)/C and Pd-(Ni-Zn-P)/C materials, containing very low Pd loadings (22-25 microg cm(-2)), were studied for the oxidation of ethanol in alkaline media in half cells and provided excellent results in terms of both specific current (as high as 3600 A g(Pd)(-1) at room temperature) and onset potential (as low as -0.6 V vs Ag/AgCl/KCl(sat)).

The heterogenization of the zwitterionic Rh(I) catalysts (sulfos)Rh(cod) (1) and (sulfos)Rh(CO)2 (2) [sulfos = -O3S(C6H4)CH2C(CH2PPh2)3; cod = cycloocta-1,5-diene] is performed by controlled adsorption on partially dehydroxylated high surface area silica. The immobilization procedure is based uniquely on the capability of the sulfonate tail of sulfos to link the silanol groups of the support via hydrogen bonding. Experimental evidence of the −SO3···HOSi− interaction between 1 or 2 and silica has been obtained from IR, Rh K-edge EXAFS, and CP MAS 31P NMR studies. The grafted catalyst (sulfos)Rh(cod)/SiO2 (1/SiO2) is active for the hydrogenation of alkenes in either flow reactors (ethene, propene) or batch reactors (styrene) in hydrocarbon solvents. The hydroformylation of alkenes, here exemplified by 1-hexene, is catalyzed exclusively in solid−liquid conditions. No Rh leaching is observed in either case. In solid−gas conditions, the catalyst 1/SiO2 is converted by syngas to the catalytically inactive, dicarbonyl derivative (sulfos)Rh(CO)2/SiO2 (2/SiO2). The termination metal products of the solid−gas reactions have been studied by EXAFS, while those of the batch reactions have been authenticated by NMR spectroscopy after extraction with methanol. In all of the cases investigated there was no evidence of the formation of contiguous Rh−Rh sites, indicating that the catalytic active sites are isolated Rh atoms, as in homogeneous phase. A comparison with analogous hydrogenation and hydroformylation reactions catalyzed by the soluble complex 1 in liquid-biphase conditions shows that the immobilized catalyst is more chemoselective and more easily recyclable than the unsupported analogue.

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Pd nanoparticles have been generated by performing an electroless procedure on a mixed ceria (CeO(2))/carbon black (Vulcan XC-72) support. The resulting material, Pd-CeO(2)/C, has been characterized by means of transmission electron microscopy (TEM), inductively coupled plasma atomic emission spectroscopy (ICP-AES), and X-ray diffraction (XRD) techniques. Electrodes coated with Pd-CeO(2)/C have been scrutinized for the oxidation of ethanol in alkaline media in half cells as well as in passive and active direct ethanol fuel cells (DEFCs). Membrane electrode assemblies have been fabricated using Pd-CeO(2)/C anodes, proprietary Fe-Co cathodes, and Tokuyama anion-exchange membranes. The monoplanar passive and active DEFCs have been fed with aqueous solutions of 10 wt% ethanol and 2 M KOH, supplying power densities as high as 66 mW cm(-2) at 25 °C and 140 mW cm(-2) at 80 °C. A comparison with a standard anode electrocatalyst containing Pd nanoparticles (Pd/C) has shown that, at even metal loading and experimental conditions, the energy released by the cells with the Pd-CeO(2)/C electrocatalyst is twice as much as that supplied by the cells with the Pd/C electrocatalyst. A cyclic voltammetry study has shown that the co-support ceria contributes to the remarkable decrease of the onset oxidation potential of ethanol. It is proposed that ceria promotes the formation at low potentials of species adsorbed on Pd, Pd(I)-OH(ads), that are responsible for ethanol oxidation.

Several palladium(II) complexes with 1,1‘-bis(diphenylphosphino)octamethylferrocene (dppomf) and its oxidized form 1,1‘-bis(diphenylphosphino)octamethylferrocenium (dppomf+) have been synthesized and characterized by spectroscopic and electrochemical methods. For comparative purposes, analogous Pd(II) derivatives with 1,1‘-bis(diphenylphosphino)ferrocene (dppf) have been also prepared. Single-crystal X-ray analyses have been carried out for the square-planar mononuclear compounds [Pd(H2O)2(dppf)](OTf)2 and [Pd(H2O)2(dppomf)](OTf)2 and for the binuclear complex [Pd(μ-OPF2O)(dppomf+)]2(BF4)4·6CH2Cl2 in which two [Pd(dppomf+)]3+ moieties are held together by the oxygen atoms of two bridging PO2F2 - groups derived from the oxidative degradation of PF6 - ions. Selected dppf and dppomf Pd(II) complexes have been employed as catalyst precursors for the methoxycarbonylation of ethene (600 psi, 1:1 CO/C2H4, 85 °C). It has been found that dppomf generates selective catalysts for the production of methyl propanoate, while dppf leads to a variety of low-molecular-weight oxygenates spanning from methyl propanoate to alternating oligoketones.