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An expeditious synthesis of metal carbide nanoparticles onto various carbon supports is demonstrated. The procedure is versatile and readily yields TiC, VC, Mo2C and W2C nanoparticles on different types of carbons. The reaction is initiated at room temperature and proceeds within seconds. This novel synthetic route paves the way for a large variety of metal carbide–carbon nanocomposites that may be implemented in emerging nanotechnology fields. [ABSTRACT FROM AUTHOR]

Efficient, robust and low cost materials as electrocatalysts for energy-related applications are highly desired for the future of renewable energy production. Here we show a simple method to fabricate nickel nitride (Ni3N) on nickel (Ni) foam for electrocatalytic applications. The Ni3N/Ni-foam exhibits extremely low overpotential (∼50 mV), high current density and excellent stability for the hydrogen evolution reaction (HER) in alkaline solution. In addition, the modified foam demonstrates enhanced activity in the oxygen evolution (OER) and reduction (ORR) reaction compared to original Ni-foam. The activity enhancement can be attributed to the facile formation of a Ni(OH)2 layer on the nitride layer due to improved lattice matching. The formation of the Ni3N/Ni(OH)2 catalyst results in lower overpotentials due to easier water dissociation on the nickel hydroxide layer. In addition, the HER is further improved due to stronger adsorption of hydrogen to the metal nitride than to the pure metal. We believe that the utilization of nickel nitride as an electrocatalyst opens opportunities for energy-related devices such as batteries and fuel cells. [ABSTRACT FROM AUTHOR]

Cobalt carbodiimide is introduced as a heterogeneous non-oxidic water oxidation catalyst prototype with dual photochemical and electrocatalytic activity in neutral and basic media. CoNCN exhibits higher initial turnover frequencies of (TOF/SBET: 2.1 × 10−1) for visible-light-driven oxygen evolution than cobalt oxide catalysts (TOF/SBET: 3.5 × 10−3) and a 18% higher oxygen yield (Ru-dye sensitized standard setup). Furthermore, CoNCN maintains stable current densities in electrolysis over 20 h, and structural tuning through cationic substitution revealed that mixed (Co, Ni)NCN catalysts with low Ni contents display higher current densities than pristine CoNCN. A wide range of bulk (XAFS/EXAFS, XRD, FTIR) and surface (XPS, EELS, HRTEM) analytical methods together with catalytic parameter variations and reference experiments were performed to confirm the stability of CoNCN under standard operational conditions. The carbodiimide matrix thus offers a straightforward structural alternative to oxide systems and a clear-cut starting point for optimization strategies and for mechanistic studies on the possible role of active carbon or nitrogen sites. This paves the way to metal carbodiimides as a novel catalyst design platform for heterogeneous energy conversion systems. [ABSTRACT FROM AUTHOR]

The concept to translate morphological and structural features from a crystalline precursor into a hybrid material is presented. Cationic organic dyes mediate the formation of loosely interconnected, highly anisotropic CuNCN crystals. Their thermal decomposition affords a macroporous CxNy polymer decorated with copper nanoislands. The hybrid is found to be highly active as hydrogenation catalysts. [ABSTRACT FROM AUTHOR]

Abstract: The influence of the pH value on the hydrothermal formation of BiVO4 photocatalysts from Bi(NO3)3·5H2O and NH4VO3 was investigated. Optimal nanostructuring and surface area values are obtained for BiVO4 nanoplatelets synthesized at pH 4. Screening of phosphorus-containing templates brought forward dimethyl methylphosphonate (DMMP) as the most efficient surfactant to fine-tune the synthesis of hierarchically structured BiVO4 architectures. Their growth processes were subsequently monitored with ex situ studies. The formation of different BiVO4 microsphere types proceeds via a gradual transformation of zircon-type BiVO4 precursors into self-organized hollow shells of monoclinic BiVO4 crystallites. A slight variation of the synthetic conditions induces the formation of dumbbell-shaped BiVO4 particles consisting of small BiVO4 building blocks arranged around a cylindrical core unit via a different pathway. Catalytic test series for organic dye degradation and water oxidation show that template-free BiVO4 nanoplatelets obtained at pH 4 exhibit optimal activity in both processes. Their MB degradation performance is further improved in alkaline media and the influence of synthetic parameter tuning on BiVO4 catalyst growth and reactivity is discussed. [Copyright &y& Elsevier]