Xing Huang

Last Name

Huang

First Name

Xing

ORCID

0000-0002-8700-0606

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Publications 1 - 10 of 29

Redox dynamics and surface structures of an active palladium catalyst during methane oxidation
Yue, Shengnan; Praveen, C.S.; Klyushin, Alexander; et al. (2024)
Nature Communications
Catalysts based on palladium are among the most effective in the complete oxidation of methane. Despite extensive studies and notable advances, the nature of their catalytically active species and conceivable structural dynamics remains only partially understood. Here, we combine operando transmission electron microscopy (TEM) with near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) and density functional theory (DFT) calculations to investigate the active state and catalytic function of Pd nanoparticles (NPs) under methane oxidation conditions. We show that the particle size, phase composition and dynamics respond appreciably to changes in the gas-phase chemical potential. In combination with mass spectrometry (MS) conducted simultaneously with in situ observations, we uncover that the catalytically active state exhibits phase coexistence and oscillatory phase transitions between Pd and PdO. Aided by DFT calculations, we provide a rationale for the observed redox dynamics and demonstrate that the emergence of catalytic activity is related to the dynamic interplay between coexisting phases, with the resulting strained PdO having more favorable energetics for methane oxidation.
Molybdenum carbide and oxycarbide from carbon-supported MoO3 nanosheets: phase evolution and DRM catalytic activity assessed by TEM and in situ XANES/XRD methods
Kurlov, Alexey; Huang, Xing; Deeva, Evgeniya B.; et al. (2020)
Nanoscale
Molybdenum carbide (β-Mo2C) supported on carbon spheres was prepared via a carbothermal hydrogen reduction (CHR) method from delaminated nanosheets of molybdenum(vi) oxide (d-MoO3/C). The carburization process was followed by combined in situ XANES/XRD analysis revealing the formation of molybdenum oxycarbide Mo2CxOy as an intermediate phase during the transformation of d-MoO3/C to β-Mo2C/C. It was found that Mo2CxOy could not be completely carburized to β-Mo2C under a He atmosphere at 750 °C, instead a reduction in H2 is required. The β-Mo2C/C obtained showed activity and stability for the dry reforming of methane at 800 °C and 8 bar. In situ XANES/XRD evaluation of the catalyst under DRM reaction conditions combined with high resolution TEM analysis revealed the evolution of β-Mo2C/C to Mo2CxOy/C. Notably, the gradual oxidation of β-Mo2C/C to Mo2CxOy/C correlates directly with the increased activity of the competing reverse water gas shift reaction.
Atomic and nanocluster Ce species on graphene oxides for selective catalytic reduction of NO with NH3
Huang, Xiaowei; Wang, Haoyang; Xin, Zhiling; et al. (2019)
Petroleum Science and Technology
Atomic-Scale Observation of the Metal–Promoter Interaction in Rh-Based Syngas-Upgrading Catalysts
Huang, Xing; Teschner, Detre; Dimitrakopoulou, Maria; et al. (2019)
Angewandte Chemie. International Edition
In-situ fabrication of nitrogen-doped carbon nanosheets containing highly dispersed single iron atoms for oxygen reduction reaction
Liu, Yuchuan; Huanga, Baobing; Zhang, Xuefei; et al. (2019)
Journal of Power Sources
From a Molecular Single-Source Precursor to a Selective High-Performance RhMnOx Catalyst for the Conversion of Syngas to Ethanol
Preikschas, Phil; Bauer, Julia; Huang, Xing; et al. (2019)
ChemCatChem
Manipulating interstitial carbon atoms in the nickel octahedral site for highly efficient hydrogenation of alkyne
Niu, Yiming; Huang, Xing; Wang, Yongzhao; et al. (2020)
Nature Communications
Light elements in the interstitial site of transition metals have strong influence on heterogeneous catalysis via either expression of surface structures or even direct participation into reaction. Interstitial atoms are generally metastable with a strong environmental dependence, setting up giant challenges in controlling of heterogeneous catalysis. Herein, we show that the desired carbon atoms can be manipulated within nickel (Ni) lattice for improving the selectivity in acetylene hydrogenation reaction. The radius of octahedral space of Ni is expanded from 0.517 to 0.524 Å via formation of Ni3Zn, affording the dissociated carbon atoms to readily dissolve and diffuse at mild temperatures. Such incorporated carbon atoms coordinate with the surrounding Ni atoms for generation of Ni3ZnC0.7 and thereof inhibit the formation of subsurface hydrogen structures. Thus, the selectivity and stability are dramatically improved, as it enables suppressing the pathway of ethylene hydrogenation and restraining the accumulation of carbonaceous species on surface.
Operando TEM study of a working copper catalyst during ethylene oxidation
Yu, Wenqian; Yue, Shengnan; Yang, Minghe; et al. (2025)
Nature Communications
Active catalysts are typically metastable, and their surface state depends on the gas-phase chemical potential and reaction kinetics. To gain relevant insights into structure-performance relationships, it is essential to investigate catalysts under their operational conditions. Here, we use operando TEM combining real-time observations with online mass spectrometry (MS) to study a Cu catalyst during ethylene oxidation. We identify three distinct regimes characterized by varying structures and states that show different selectivities with temperature, and elucidate the reaction pathways with the aid of theoretical calculations. Our findings reveal that quasi-static Cu2O at low temperatures is selective towards ethylene oxide (EO) and acetaldehyde (AcH) via an oxometallacycle (OMC) pathway. In the dynamic Cu0/Cu2O oscillation regime at medium temperatures, partially reduced and strained oxides decrease the activation energies associated with partial oxidation. At high temperatures, the catalyst is predominantly Cu0, partially covered by a monolayer Cu2O. While Cu0 is extremely efficient in dehydrogenation and eventual combustion, the monolayer oxide favors direct EO formation. These results challenge conclusions drawn from ultra-high vacuum studies that suggested metallic copper would be a selective epoxidation catalyst and highlight the need for operando study under realistic conditions.
Controlling the Strong Metal-Support Interaction Overlayer Structure in Pt/TiO2 Catalysts Prevents Particle Evaporation
Beck, Arik; Frey, Hannes; Huang, Xing; et al. (2023)
Angewandte Chemie. International Edition
Platinum nanoparticles (NPs) supported by titania exhibit a strong metal-support interaction (SMSI)[1] that can induce overlayer formation and encapsulation of the NP's with a thin layer of support material. This encapsulation modifies the catalyst's properties, such as increasing its chemoselectivity[2] and stabilizing it against sintering.[3] Encapsulation is typically induced during high-temperature reductive activation and can be reversed through oxidative treatments.[1] However, recent findings indicate that the overlayer can be stable in oxygen.[4, 5] Using in situ transmission electron microscopy, we investigated how the overlayer changes with varying conditions. We found that exposure to oxygen below 400 °C caused disorder and removal of the overlayer upon subsequent hydrogen treatment. In contrast, elevating the temperature to 900 °C while maintaining the oxygen atmosphere preserved the overlayer, preventing platinum evaporation when exposed to oxygen. Our findings demonstrate how different treatments can influence the stability of nanoparticles with or without titania overlayers. expanding the concept of SMSI and enabling noble metal catalysts to operate in harsh environments without evaporation associated losses during burn-off cycling.
CO2 Hydrogenation to CH3OH on Supported Cu Nanoparticles: Nature and Role of Ti in Bulk Oxides vs Isolated Surface Sites
Noh, Gina; Docherty, Scott; Lam, Erwin; et al. (2019)
The Journal of Physical Chemistry C

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