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Abstract The concurrent production of CO x -free hydrogen and multi-walled carbon filaments by thermocatalytic decomposition of methane is advantageous in the environmental and energy catalysis. In the present work, a facile "one-pot" evaporation-induced self-assembly strategy was effectively adopted to fabricate the nickel catalysts supported on mesoporous Al 2 O 3 , SiO 2 , TiO 2 , and MgO, and their catalytic activities for methane decomposition were evaluated for the first time. The structural, textural, and redox properties of the as-obtained materials were characterized using a number of analytical techniques. The nitrogen sorption analysis indicated the presence of a mesoporous structure due to homogeneous aggregation of the catalyst particles with a high specific surface area of 32–236 m2/g. Among all of the catalysts, Ni/MgO exhibited the best catalytic activity for methane decomposition (65% methane conversion at 600 °C and GHSV of 48,000 mL/(g h)). The activity increased when Ni loading increased from 25 to 55 wt%. The investigation on the correlation between catalytic performance and promoter doping effect suggests that incorporating copper into the MgO support considerably enhanced the catalytic activity and stability at high temperatures. The XPS results reveal that doping of Cu to Ni/MgO enhanced the adsorption and activation of oxygen molecules. In addition, the disordered crystalline carbon filaments with different diameters and good crystallinity were generated on the surface of the Cu-doped Ni/MgO catalysts. Graphical abstract Unlabelled Image Highlights • The work is focused on pure hydrogen production via catalytic CH 4 decomposition. • One-pot synthesis allows to prepare Ni catalysts supported on various metal oxide. • The catalysts were characterized for their physicochemical properties and activity. • The Ni supported on MgO shows a higher activity than that supported on other metal oxides. • Effect of Ni content and Cu addition in Ni/MgO were investigated in detail. [ABSTRACT FROM AUTHOR]

Three-dimensionally ordered macroporous (3DOM) CoFe 2 O 4 , z MnO x /3DOM CoFe 2 O 4 ( z = 4.99–12.30 wt%), and y Pd–Pt/6.70 wt% MnO x /3DOM CoFe 2 O 4 ( y = 0.44–1.81 wt%; Pd/Pt molar ratio = 2.1–2.2) have been prepared using the polymethyl methacrylate microspheres-templating, incipient wetness impregnation, and bubble-assisted polyvinyl alcohol-protected reduction strategies, respectively. All of the samples were characterized by means of various techniques. Catalytic performance of the samples was measured for methane combustion. It is shown that the as-prepared samples exhibited a high-quality 3DOM structure (103 ± 20 nm in pore size) and a surface area of 19–28 m 2 /g, and the noble metal or alloy nanoparticles (NPs) with a size of 2.2–3.0 nm were uniformly dispersed on the macropore wall surface of 3DOM CoFe 2 O 4 . The loading of MnO x on CoFe 2 O 4 gave rise to a slight increase in activity, however, the dispersion of Pd–Pt NPs on 6.70MnO x /3DOM CoFe 2 O 4 significantly enhanced the catalytic performance, with the 1.81Pd 2.1 Pt/6.70MnO x /3DOM CoFe 2 O 4 sample showing the highest activity ( T 10% = 255 °C, T 50% = 301 °C, and T 90% = 372 °C at a space velocity of 20,000 mL/(g h)). We believe that the excellent catalytic activity of 1.81Pd 2.1 Pt/6.70MnO x /3DOM CoFe 2 O 4 was related to its well-dispersed Pd–Pt alloy NPs, high adsorbed oxygen species concentration, good low-temperature reducibility, and strong interaction between MnO x or Pd–Pt NPs and 3DOM CoFe 2 O 4 . [ABSTRACT FROM AUTHOR]