Ce-MnO_x composite oxide catalysts with different proportions were prepared using the coprecipitation method, and the CO-removal ability of the catalysts with the tested temperature range of 60–140 °C was investigated systematically. The effect of Ce and Mn ratios on the catalytic oxidation performance of CO was investigated using X-ray diffraction (XRD), X-ray energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), H₂ temperature programmed reduction (H₂-TPR), CO-temperature programmed desorption (CO-TPD), and in situ infrared spectra. The experimental results reveal that under the same test conditions, the CO conversion rate of pure Mn₃O₄ reaches 95.4% at 170 °C. Additionally, at 140 °C, the Ce-MnO_x series composite oxide catalyst converts CO at a rate of over 96%, outperforming single-phase Mn₃O₄ in terms of catalytic performance. With the decrement in Ce content, the performance of Ce-MnO_x series composite oxide catalysts first increase and then decrease. The Ce MnO_x catalyst behaves best when Ce:Mn = 1:1, with a CO conversion rate of 99.96% at 140 °C and 91.98% at 100 °C.

Ni-based alloy is an ideal candidate for its application in the field of hydrogen evolution of water splitting due to its good durability, excellent catalytic properties and low hydrogen evolution overpotential. In this paper, porous Ni-Sn alloy materials were prepared by activation reaction sintering, and the pore structure was tailored by adjusting Sn content. The effects of Sn content and electrolyte temperature on the hydrogen evolution properties of porous Ni-Sn alloy electrodes in 6 mol·L⁻¹ KOH solution were studied by electrochemical measurement methods, such as cyclic voltammetry (CV) curves, electrochemical impedance spectroscopy (ESI) and linear sweep voltammetry, and the mechanism of hydrogen evolution was further discussed. The experimental results reveal that when Sn content is 45 wt%, porous Ni-Sn alloy exhibits the best catalytic performance for hydrogen evolution with a Tafel slope of 164.69 mV·dec⁻¹ and an overpotential of 170 mV. The tested electrode also shows good stability for hydrogen evolution in alkaline solution, and the apparent activation energy calculated at room temperature is 29.645 kJ·mol⁻¹. The catalytic mechanism of hydrogen evolution is as follows: the addition of Sn significantly reduces the dissociation degree of M-H bonds, thereby reducing the overpotential of hydrogen evolution; with the increase of Sn content, the porous Ni-Sn electrode displays a higher electrochemical active surface area (ECSA), which makes porous Ni-Sn alloy exhibit good hydrogen evolution catalytic performance.

Mo, TiH₂, Al and graphite elemental powders were used as starting materials for the activation reaction sintering process, which was employed to fabricate porous Mo₂TiAlC₂. The alteration of phase constitution, volume expansion, porosity, pore size and surface morphology of porous Mo₂TiAlC₂ with sintering temperatures ranging from 700 °C to 1500 °C were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and pore size tester. Both the pore formation mechanism and activation reaction process at each temperature stage were investigated. The experimental results illustrate that the sintered discs of porous Mo₂TiAlC₂ exhibit obvious volume expansion and pore structure change during the sintering process. Before 1300 °C, the volume expansion rate and porosity increase with the increment of temperature. However, with the sintering temperature above 1300 °C, the volume expansion rate and porosity decrease. At the final sintering temperature of 1500 °C, porous Mo₂TiAlC₂ with a volume expansion rate of 35.74%, overall porosity of 47.1%, and uniform pore structure was synthesized. The pore-forming mechanism of porous Mo₂TiAlC₂ is discussed, and the evolution of pressed pores, the removal of molding agents, the decomposition of TiH₂, and the Kirkendall effect caused by different diffusion rates of elements in the diffusion reaction are all accountable for the formation of pores.