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A safe and simple method to fabricate air-stable nickel nitride and nickel embedded in carbon and nitrogen matrix, with high surface area for catalytic applications, is presented. The new synthesis employs molten inorganic salts as the reaction media. The use of salt melt opens new possibilities for safe, simple, and cheap synthesis of metal nitrides and metals for energy-related applications.

International audience; 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.

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.

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.

A flexible, sustainable, one-step thermal decomposition route for the synthesis of hierarchical, heteroatom doped carbon foams is presented. Task-specific semi-organic crystals combine functions for three different purposes: the carbon and heteroatom source, a foaming agent (CO2) and an in situ generable template (NaCl). Insights to the decomposition pathway were gained through FTIR/MS coupled TGA and an ultrafast out-of-furnace heating procedure and the products were analysed with (HR)SEM/TEM, EELS, FTIR, and N2 sorption. The resulting macroporous carbon foams are excellent supports for metallic nanoparticles due to their hierarchical structure, high surface area and tuneable heteroatom contents. This was demonstrated for catalytically active copper or the magnetic CoNi alloy for water purification.

The influence of the pH value on the hydrothermal formation of BiVO 4 photocatalysts from Bi(NO 3 ) 3 ·5H 2 O and NH 4 VO 3 was investigated. Optimal nanostructuring and surface area values are obtained for BiVO 4 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 BiVO 4 architectures. Their growth processes were subsequently monitored with ex situ studies. The formation of different BiVO 4 microsphere types proceeds via a gradual transformation of zircon-type BiVO 4 precursors into self-organized hollow shells of monoclinic BiVO 4 crystallites. A slight variation of the synthetic conditions induces the formation of dumbbell-shaped BiVO 4 particles consisting of small BiVO 4 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 BiVO 4 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 BiVO 4 catalyst growth and reactivity is discussed.

A compact apparatus employing heating with concentrated light was designed for desktop laboratory application to run syntheses in the range 200–850 °C in short times under a satisfying control of the temperature, heating ramps, and adjustable chemical environments. The device is composed of 4 halogen lamps oriented to a centre point and allows fast heating rates up to 100 K min−1 of medium size scale samples (volume < 7 mL). This method can be proven to be more energetically efficient and allows for better temperature control over standard furnace methods. Herein we exemplify with a typical high temperature synthesis of non-oxide ceramic (vanadium nitride) nanoparticles. These nanoparticles can be obtained in different sizes and crystallinity ranges by varying the reaction conditions, following the urea glass route and applying the non-classical rapid heating method. Nanoparticles containing both carbon and nitrogen and showing the typical crystal structure of VN were obtained with sizes below 10 nm within a short reaction time (5 min at 750 °C) and in a fast heating procedure (50 K min−1). Moreover, quasi-quenching of samples through a fast cooling procedure allows the detection of various intermediate oxide species that otherwise were not observed.