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This work investigates selective Ni locations over Ni/CeZrO x –Al 2 O 3 catalysts at different Ni loading contents and their influences on reaction pathways in ethanol steam reforming (ESR). Depending on the Ni loading contents, the added Ni selectively interacts with CeZrO x –Al 2 O 3 , resulting in the stepwise locations of Ni over CeZrO x –Al 2 O 3. This behavior induces a remarkable difference in hydrogen production and coke formation in ESR. The selective interaction between Ni and CeZrO x for 10-wt.% Ni generates more oxygen vacancies in the CeZrO x lattice. The Ni sites near the oxygen vacancies enhance reforming via steam activation, resulting in the highest hydrogen production rate of 1863.0 μmol/g cat ·min. In contrast, for 15 and 20-wt.% Ni, excessive Ni is additionally deposited on Al 2 O 3 after the saturation of Ni–CeZrO x interactions. These Ni sites on Al 2 O 3 accelerate coking from the ethylene produced on the acidic sites, resulting in a high coke amount of 19.1 mg c /g cat·h (20Ni/CZ-Al). [Display omitted] • Ni/CeZrO x –Al 2 O 3 for ethanol steam reforming are prepared at different Ni contents. • Depending on the Ni amounts, Ni selectively interacts with the CeZrO x –Al 2 O 3 support. • Stepwise Ni locations over CeZrO x –Al 2 O 3 remarkably affect the ESR reaction pathways. • Ni sites near the oxygen vacancies on CeZrO x enhance reforming via steam activation. • Ni sites on Al 2 O 3 accelerate coking from the ethylene produced on the acidic sites. [ABSTRACT FROM AUTHOR]

[Display omitted] • Manipulating metal-support interactions in Ni/CZA catalysts were investigated. • 20Ni/40CZA contained highly dispersed Ni nanoparticles and abundant oxygen vacancies. • 20Ni/40CZA exhibited the highest H 2 production rate and the lowest coke formation. • Coke precursor gasification was promoted by the efficient delivery of active oxygen. Understanding coke formation routes over Ni-based catalysts is essential in determining the catalytic performance in ethanol steam reforming. In this study, we focused on optimizing the active sites distribution via the metal-support interactions and understanding the coke precursor gasification in Ni/Ce x Zr 1-x O 2 –Al 2 O 3 (CZA) catalysts for ethanol steam reforming. We found that the optimized active sites distribution could minimize coke formation by enabling efficient gasification of a coke precursor on Ni. In the 20Ni/40CZA catalyst, the crystalline CZ exhibited a strong interaction with Ni, maintaining a uniform distribution of highly dispersed Ni nanoparticles and creating abundant oxygen vacancies on CZ, even at 20 wt% of Ni loading. Consequently, the resistance to coking over 20Ni/40CZA was significantly enhanced due to the efficient delivery of active oxygen atoms from steam on the abundant oxygen vacancies to the coke precursor on the Ni surface, resulting in fast gasification of the coke precursor. [ABSTRACT FROM AUTHOR]

In this study, we investigated the metal–support interactions over Ni/CeO 2 –ZrO 2 (Ni/CZ) catalysts for ethanol steam reforming. Different Ni contents (5, 10, and 15 wt%) were loaded onto the CZ support using two catalyst preparation methods, namely one-pot, and successive impregnation methods. Using the one-pot method, the Ni species over the Ni/CZ catalysts strongly interacted with the CZ support, resulting in smaller Ni nanoparticles with abundant oxygen vacancies. In contrast, the successive impregnation method mainly generated an isolated Ni phase at a high Ni content, resulting in large Ni clusters with limited oxygen vacancies. The poor Ni dispersion over the Ni/CZ catalysts prepared by the successive impregnation method induced low ethanol conversions and hydrogen production rates. In addition, the large Ni clusters over the Ni/CZ catalysts prepared by the successive impregnation method achieved a fast-coking behavior, thereby increasing the coke amount. Further, coke gasification was demonstrated to dominate the Ni surface with the Ni/CZ catalysts prepared by the one-pot method because of the high Ni dispersion and abundant oxygen vacancies. [Display omitted] • Ni/CeO 2 -ZrO 2 catalysts for ethanol steam reforming are prepared at different methods. • The one-pot method induces the strong Ni-CZ interaction over Ni/CZ catalysts. • Ni/CZ prepared by the one-pot method contains abundant oxygen species and Ni sites. • Ni/CZ prepared by the one-pot method enhances the H 2 production rate at 550 ℃. • Mild coking on the one-pot Ni/CZ catalysts is due to efficient coke gasification. [ABSTRACT FROM AUTHOR]

Abstract: CeO2 hollow microspheres have been fabricated through a simple thermal decomposition of precursor approach. The precursor with an average size of 10 μm was prepared in a reverse microemulsions containing Ce(NO3)3·6H2O and CO(NH2)2 at 160 °C. The products were characterized by X-ray powder diffraction (XRD), transmission electron microscope (TEM), selected area electron diffraction (SAED) and scanning electron microscopy (SEM). The possible formation mechanism of hollow spheres was discussed. In addition, the CeO2 hollow microspheres modified glassy carbon electrode exhibit excellent sensing performance towards methyl orange, which provide a new application of CeO2 hollow spheres. The catalytic activity of CeO2 hollow spheres on the thermal decomposition of ammonium perchlorate (AP) also was investigated by TGA. The catalytic performance of CeO2 hollow spheres is superior to that of commercial CeO2 powder. [ABSTRACT FROM AUTHOR]

• Self-supporting ternary alloy catalyst was prepared by one step growth. • The principle of interface reaction at the atomic level. • Excellent HER properties attributed to ternary alloy catalysts structure. Active electrocatalysts are the key of water splitting for hydrogen production through the electrolysis. In this paper, Ni foams substrates as templates, self-supporting ternary alloy catalyst was prepared by one step at room temperature. Growth mechanism of self-supporting ternary alloy catalyst is explored by growth process. Micro-current technology of galvanic reaction and the principle of interface electric double layer reaction are important to the self-supporting ternary alloy catalyst. Their catalytic activity was evaluated by electrocatalytic hydrogen evolution(HER). It exhibits excellent HER properties with a overpotential (17 mV) and small Tafel slope (10.2 mVdec−1). Their enhanced performances in HER catalysts can be mainly attributed to ternary alloy catalysts structure, which allows the appearance synergistic effects and larger specific surface area. This research is to control the micro-area of chemical reaction at the atomic level by non-precious template and all kinds of precursor mixture solution. Self-supporting ternary alloy catalyst was prepared by one-step galvanic replacement. They display exerlent superior activity for the HER in base solution with an onset reduction potential of + 17 mV vs RHE and small Tafel slope (10.2 mVdec−1). This activity is due to the synergistic effects and larger specific surface area. [Display omitted]. [ABSTRACT FROM AUTHOR]