Dislocation-induced stop-and-go kinetics of interfacial transformations

Sun, Xianhu; Wu, Dazhuan; Zou, Lianfeng; House, Stephen D.; Chen, Xiaobo; Li, Meng; Zakharov, Dmitri N.; Yang, Judith C.; Zhou, Guangwen

doi:10.1038/s41586-022-04880-1

Cited by 67 publications

(31 citation statements)

References 38 publications

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“…Our AP-XPS and AP-STM results for CuO x /Cu(111) agree well with previous studies, − , showing kinetically limited H 2 dissociation (Figures and ) and a long induction time that plays a central role in an autocatalytic process (Figure ). During this induction time, there is only a small amount of OH groups on the surface, and according to the results of AP-XPS studies and DFT calculations, the H 2 molecules mainly react with nonlattice oxygen atoms to form H 2 O molecules.…”

Section: Discussionsupporting

confidence: 91%

“…59,63 Furthermore, the surface chemistry associated with a CO 2 → CH 3 OH transformation is usually facilitated by the H-rich surfaces. 2,20,23,59,63 Taking this into consideration, we can conclude that the addition of ZnO to copper is a very important step for the catalytic conversion of CO 2 . DFT results show exothermic processes for the dissociation of H 2 on nanoparticles (ΔE: −2.00 eV, Figure 10) and bilayer films (ΔE: −1.5 eV) 25 of ZnO supported on Cu(111).…”

Section: ■ Discussionmentioning

confidence: 96%

“…The dissociation of H 2 on Cu-based catalysts is a key step in the conversion of CO 2 to methanol. − , The CO 2 does not bind well to copper surfaces and the H adatoms do facilitate the binding of the molecule. , Furthermore, the surface chemistry associated with a CO 2 → CH 3 OH transformation is usually facilitated by the H-rich surfaces. ,,,, Taking this into consideration, we can conclude that the addition of ZnO to copper is a very important step for the catalytic conversion of CO 2 . DFT results show exothermic processes for the dissociation of H 2 on nanoparticles (Δ E : −2.00 eV, Figure ) and bilayer films (Δ E : −1.5 eV) of ZnO supported on Cu(111).…”

Section: Discussionmentioning

confidence: 99%

“…In general, the formation of the product phase (either Cu 2 O or Cu) was triggered once a certain density of accumulated oxygen vacancies was reached at the periphery of the parent phase (either CuO or Cu 2 O). , Moreover, the O-deficient Cu 2 O can form a stable intermediate before the Cu 2 O is fully reduced to metallic Cu. Many of these findings have been verified in subsequent studies involving transmission electron microscopy (TEM) or scanning tunneling microscopy (STM). − The results of calculations based on density functional theory (DFT) indicate that when one H 2 molecule is placed on the top of surface O, the H 2 molecule dissociates spontaneously into two H atoms that bond with the adjacent lattice O to form two hydroxyls. , Eventually, hydrogen adsorption leads to the formation of H 2 O that evolves spontaneously from the surface leaving behind a reduced oxide. The combined process of H 2 dissociation and H 2 O formation is accelerated by the presence of defects or dislocations in the copper oxide. − These findings are important for understanding the role of defect stability on the lifetime of transient structures seen in the reduction mechanisms.…”

Section: Introductionmentioning

confidence: 94%

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Microscopic Investigation of H₂ Reduced CuO_x/Cu(111) and ZnO/CuO_x/Cu(111) Inverse Catalysts: STM, AP-XPS, and DFT Studies

et al. 2023

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Understanding the reduction mechanism of ZnO/CuO x interfaces by hydrogen is of great importance in advancing the performance of industrial catalysts used for CO and CO 2 hydrogenation to oxygenates, the water-gas shift, and the reforming of methanol. Here, the reduction of pristine and ZnO-modified CuO x /Cu(111) by H 2 was investigated using ambient-pressure scanning tunneling microscopy (AP-STM), ambient-pressure X-ray photoelectron spectroscopy (AP-XPS), and density functional theory (DFT). The morphological changes and reaction rates seen for the reduction of CuO x /Cu(111) and ZnO/CuO x /Cu(111) are very different. On CuO x /Cu(111), perfect "44" and "29" structures displayed a very low reactivity toward H 2 at room temperature. A long induction period associated with an autocatalytic process was observed to enable the reduction by the removal of chemisorbed nonlattice oxygen initially and lattice oxygen sequentially at the CuO x −Cu interface, which led to the formation of oxygen-deficient "5−7" hex and honeycomb structures. In the final stages of the reduction process, regions of residual oxygen species and metallic Cu were seen. The addition of ZnO particles to CuO x /Cu(111) opened additional reaction channels. On the ZnO sites, the dissociation of H 2 was fast and H adatoms easily migrated to adjacent regions of copper oxide. This hydrogen spillover substantially enhanced the rate of oxygen removal, resulting in the rapid reduction of the copper oxide located in the periphery of the zinc oxide islands with no signs of the reduction of ZnO. The deposited ZnO completely modified the dynamics for H 2 dissociation and hydrogen migration, providing an excellent source for CO 2 hydrogenation processes on the inverse oxide/metal system.

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Section: Discussionsupporting

confidence: 91%

Section: ■ Discussionmentioning

confidence: 96%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 94%

See 2 more Smart Citations

Microscopic Investigation of H₂ Reduced CuO_x/Cu(111) and ZnO/CuO_x/Cu(111) Inverse Catalysts: STM, AP-XPS, and DFT Studies

et al. 2023

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“…In the Cu@TiOx catalyst, the morphological changes associated with the oxidation and reduction of the copper component are affected by metal-support interactions and show clear differences with respect to those seen in plain copper oxide systems with E-TEM. 42,43,44 Furthermore, during CO2 hydrogenation, morphological changes are seen that have not been detected previously in E-TEM images collected while exposing metal/oxide catalysts to either plain H2 or under CO oxidation. 11,27,42,44 These morphological changes may be responsible for the difficulties reported when establishing the active phase for catalysts used in CO2 hydrogenation.…”

Section: Resultsmentioning

confidence: 67%

In situ Imaging and Tracking of Reversible Metal-Support Interactions under CO2 Hydrogenation over a Cu@TiOx Core@shell Catalyst

Deng

Chen

Moncada

et al. 2023

Preprint

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A combination of environmental-transmission electron microscopy (E-TEM), several in-situ techniques (XRD, PDF, XAFS, AP-XPS), and transient isotopic exchange analysis was used to explore links between the structural and chemical properties of a Cu@TiOx core@shell catalyst under CO2 hydrogenation conditions. The active phase of the catalyst involved an oxide/metal configuration, but the initial core@shell motif was disrupted. Images of E-TEM showed a very dynamic morphology, where the inverse oxide/metal configuration was substantially affected by the gas environment (CO2, H2, or CO2/H2) and the temperature of the system. At room temperature, CO2 was very reactive at the metal-oxide interface, producing big changes in its morphology. When the initial system was oxidized by reaction with carbon dioxide (CO2,gas → COgas + Oads), the copper leached out and disrupted the titania shell. However, the core@shell structure was regenerated by hydrogen reduction at 150-250 oC. When oxidation and reduction occurred at the same time, under a mixture of CO2 and H2, the surface structure evolved toward a dynamic equilibrium that strongly depended on the temperature. At room temperature, the leaching of copper dominated, while, at 250 °C, the formation and development of an evolving Cu@TiOx structure prevailed. These morphological changes were linked to variations in metal-support interactions that were completely reversible with temperature or chemical environment and affected the catalytic activity of the system.

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Unique Semi‐Coherent Nanostructure Advancing Thermoelectrics of N‐Type PbSe

Deng,

Zhang,

Nan

et al. 2023

Adv Funct Materials

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Introducing nanostructures into bulk thermoelectric materials is an effective strategy for reducing lattice thermal conductivity (κlat). However, large numbers of hanging bonds emerge on account of lattice mismatch usually at the interfaces between nanostructures and matrix, thereby significantly deteriorating carrier mobility (µH) and seriously limiting thermoelectric performance. Here, utilizing the cointroduction of Gd‐Cu2Te into n‐type PbSe as a paradigm, the zT could be greatly improved. The conduction band flattening caused by Gd doping can successfully compensate for the small Seebeck coefficient in n‐type PbSe, thus achieving extraordinary electrical performance. Further advanced electron microscopy and X‐ray absorption fine structure spectra directly demonstrate that most of the Cu forms nanoscale Cu2Se precipitates, especially a unique semi‐coherent interface between the PbSe matrix and the Cu2Se nanoprecipitate is observed for the first time. Such nanoprecipitate accompanied by the semi‐coherent interface not only ensures higher µH as an excellent charge transfer mediator but also collectively scatters the heat‐carrying phonons over a wide frequency range to obtain the ultralow κlat, resulting in the prominent improvement of the ratio µH/κlat. The present finding represents an important step forward in electron–phonon decoupling via constructing semi‐coherent nanostructure and interface engineering, which should be applicable for other thermoelectric materials.

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Dislocation-induced stop-and-go kinetics of interfacial transformations

Cited by 67 publications

References 38 publications

Microscopic Investigation of H₂ Reduced CuO_x/Cu(111) and ZnO/CuO_x/Cu(111) Inverse Catalysts: STM, AP-XPS, and DFT Studies

Microscopic Investigation of H₂ Reduced CuO_x/Cu(111) and ZnO/CuO_x/Cu(111) Inverse Catalysts: STM, AP-XPS, and DFT Studies

In situ Imaging and Tracking of Reversible Metal-Support Interactions under CO2 Hydrogenation over a Cu@TiOx Core@shell Catalyst

Unique Semi‐Coherent Nanostructure Advancing Thermoelectrics of N‐Type PbSe

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Dislocation-induced stop-and-go kinetics of interfacial transformations

Cited by 67 publications

References 38 publications

Microscopic Investigation of H2 Reduced CuOx/Cu(111) and ZnO/CuOx/Cu(111) Inverse Catalysts: STM, AP-XPS, and DFT Studies

Microscopic Investigation of H2 Reduced CuOx/Cu(111) and ZnO/CuOx/Cu(111) Inverse Catalysts: STM, AP-XPS, and DFT Studies

In situ Imaging and Tracking of Reversible Metal-Support Interactions under CO2 Hydrogenation over a Cu@TiOx Core@shell Catalyst

Unique Semi‐Coherent Nanostructure Advancing Thermoelectrics of N‐Type PbSe

Contact Info

Product

Resources

About

Microscopic Investigation of H₂ Reduced CuO_x/Cu(111) and ZnO/CuO_x/Cu(111) Inverse Catalysts: STM, AP-XPS, and DFT Studies

Microscopic Investigation of H₂ Reduced CuO_x/Cu(111) and ZnO/CuO_x/Cu(111) Inverse Catalysts: STM, AP-XPS, and DFT Studies