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Ni-based catalysts supported on ordered mesoporous Al 2 O 3 with 2-D hexagonal and 3-D cubic pore structures are synthesized via evaporation-induced self-assembly for catalyzing dry CH 4 reforming to produce syngas. The Ni–Al 2 O 3 catalysts with 3-D pore structure exhibit higher activity in terms of CH 4 and CO 2 conversions than those with 2-D pore symmetry, due to the better mass transfer of the 3-D interconnected pore structure for the accessibility of Ni0 active sites. And a higher Ni content slightly promotes catalytic activity, owing to more exposed active sites. However, a higher Ni content causes more severe carbon deposition during long-term reaction. During the long-term stability tests, the catalysts with 2.5 wt% Ni maintain the highest stability regardless of the pore structure, and the catalyst with 3-D pore structure is more advantageous to both activity and stability. Meanwhile, the catalyst with 2.5 wt% Ni and 3-D pore structure shows the lowest carbon deposition. • Mesoporous Ni–Al 2 O 3 catalysts with different pore structure are synthesized for DMR. • Effect of pore structure on catalyst performance is investigated for the first time. • Ni–Al 2 O 3 catalyst with 3-D cubic mesopores shows higher activity and stability. • Ni–Al 2 O 3 catalyst with lower Ni content has stronger carbon deposition resistance. [ABSTRACT FROM AUTHOR]

The design of high-performance and low-cost oxygen evolution reaction (OER) electrocatalysts is crucial for environment friendly hydrogen production. Some transition metals have been proven to be good substitutes for noble metals due to their unique electronic structural characteristics and good electrocatalytic performances, with examples including nickel and cobalt, which are usually used to prepare OER electrocatalysts. In this work, we synthesized three-dimensional Ni-Co-Fe ternary layered double hydroxide nanosheet array electrocatalysts via hydrothermal process. Iron element was introduced into the Ni-Co based hydroxide. The ternary layered double hydroxide has a nanoarrays microstructure. Theoretical analysis confirms that by adjusting the ratio of Ni/Co/Fe, the microstructure of the catalyst changes significantly. Attributed to the special nanostructure, the catalysts show superior catalytic activities in oxygen evolution reaction (OER). The results show that a small overpotential of 222 mV at the current density of 20 mA·cm−2 for the OER in 1.0 M KOH is acquired. A small Tafel slope of 61.22 mVdec−1 and a maximum specific capacitance of 239 Fg−1 are also obtained. [ABSTRACT FROM AUTHOR]

Oxygen evolution reaction is a key process in hydrogen production from water splitting. The development of non-noble metal electrode materials with high efficiency and low cost has become the key factor for large-scale hydrogen production. Binary NiCo-layered double hydroxide (LDH) has been used as a non-noble metal electrocatalyst for OER, but its overpotential is still large. The microstructure of the catalyst is tuned by doping Mo ions into the NiCo-LDH/NF nanowires to form ternary NiCoMo-LDH/NF nanosheet catalysts for the purpose of enhancing the active sites and reducing the initial overpotential. Only 1.5 V (vs. reversible hydrogen electrode (RHE), ≈270 mV overpotential) is required to achieve a catalytic current density of 10 mA cm−2 and a small Tafel slope of 81.46 mV dec−1 in 1 M KOH solution, which manifests the best performance of NiCo-based catalysts reported up to now. Electrochemical analysis and micro-morphology show that the high catalytic activity of NiCoMo-LDH/NF is attributable to the change of the microstructure. The interconnected nanosheet arrays have the obvious advantages of electrolyte diffusion and ion migration. Thus, the active sites of catalysts are significantly increased, which facilitates the adsorption and desorption of intermediates. We conclude that NiCoMo-LDH/NF is a promising electrode material for its low cost and excellent electrocatalytic properties. [ABSTRACT FROM AUTHOR]

The introduction of catalyst on anode of solid oxide fuel cell (SOFC) has been an effective way to alleviate the carbon deposition when utilizing biogas as the fuel. A series of La 0.6 Sr 0.4 Co 1-x Ni x O 3-δ (x = 0, 0.2, 0.4, 0.6, 0.8) oxides are synthesized by sol-gel method and used as catalysts precursors for biogas dry reforming. The phase structure of La 0.6 Sr 0.4 Co 1-x Ni x O 3-δ oxides before and after reduction are characterized by X-ray diffraction (XRD). The texture properties, carbon deposition, CH 4 and CO 2 conversion rate of La 0.6 Sr 0.4 Co 1-x Ni x O 3-δ catalysts are evaluated and compared. The peak power density of 739 mW cm−2 is obtained by a commercial SOFC with La 0.6 Sr 0.4 Co 0.4 Ni 0.6 O 3-δ catalyst at 850 °C when using a mixture of CH 4 : CO 2 = 2:1 as fuel. This shows a great improvement from the cell without catalyst for internal dry reforming, which is attributed to the formation of NiCo alloy active species after reduction in H 2 atmosphere. The results indicate the benefits of inhibiting the carbon deposition on Ni-based anode through introducing the La 0.6 Sr 0.4 Co 0.4 Ni 0.6 O 3-δ catalyst precursor. Additionally, the dry reforming technology will also help to convert part of the exhaust heat into chemical energy and improve the efficiency of SOFC system with biogas fuel. • Dry reforming of biogas between methane and CO 2 is studied. • The texture properties and catalytic activity of La 0.6 Sr 0.4 Co 1-x Ni x O 3-δ catalysts are examined systematically. • The presence of NiCo alloy active species can possible alleviate the carbon deposition of anode layer of single cell. • The single cell with La 0.6 Sr 0.4 Co 0.4 Ni 0.6 O 3-δ catalyst exhibits 739 mW cm−2 at internal reforming of CH 4 :CO 2 = 2:1 at 850. [ABSTRACT FROM AUTHOR]