Light-Reinforced Key Intermediate for Anticoking To Boost Highly Durable Methane Dry Reforming over Single Atom Ni Active Sites on CeO₂.

Dry reforming of methane (DRM) has been investigated for more than a century; the paramount stumbling block in its industrial application is the inevitable sintering of catalysts and excessive carbon emissions at high temperatures. However, the low-temperature DRM process still suffered from poor reactivity and severe catalyst deactivation from coking. Herein, we proposed a concept that highly durable DRM could be achieved at low temperatures via fabricating the active site integration with light irradiation. The active sites with Ni-O coordination (NiSA/CeO2) and Ni-Ni coordination (NiNP/CeO2) on CeO2, respectively, were successfully constructed to obtain two targeted reaction paths that produced the key intermediate (CH3O*) for anticoking during DRM. In particular, the operando diffuse reflectance infrared Fourier transform spectroscopy coupling with steady-state isotopic transient kinetic analysis (operando DRIFTS-SSITKA) was utilized and successfully tracked the anticoking paths during the DRM process. It was found that the path from CH3* to CH3O* over NiSA/CeO2 was the key path for anticoking. Furthermore, the targeted reaction path from CH3* to CH3O* was reinforced by light irradiation during the DRM process. Hence, the NiSA/CeO2 catalyst exhibits excellent stability with negligible carbon deposition for 230 h under thermo-photo catalytic DRM at a low temperature of 472 °C, while NiNP/CeO2 shows apparent coke deposition behavior after 0.5 h in solely thermal-driven DRM. The findings are vital as they provide critical insights into the simultaneous achievement of low-temperature and anticoking DRM process through distinguishing and directionally regulating the key intermediate species

Modulating the Growth of Epitaxial MoS₂ on Au(111) Surfaces <i>via</i> an Ultra-High-Vacuum-Interconnected Apparatus

The intriguing two-dimensional (2D) molybdenum disulfide (MoS2) has unique potential in next-generation nanoelectronics and optoelectronics, engendering intense interest in its synthesis, especially using chemical vapor deposition (CVD). However, achieving high-quality 2D MoS2 remains a challenge, primarily limited by substrate quality in most instances. Herein, we develop an elegant way to create atomic-level well-defined Au(111) single-crystal films by ultra-high-vacuum (UHV)-interconnected techniques, including sputtering, annealing, and imaging, avoiding the environmental-impurity damage during crystallization and surface reconstruction compared to normal atmosphere-based operation. Benefiting from substrate engineering, this work succeeded in the epitaxial growth of uniform MoS2 monolayers using the CVD approach and further investigated the growth dynamics affected by key factors. It was revealed that the “substrate-to-precursor” distance determines the fluid-transfer-related growth region and modulates the morphology regularity, where the laminar-flow condition rather than the turbulence favors regular MoS2 monolayers. The S/Mo ratio contributes to the domain morphology and crystal orientation. Sulfur vapor transport and reaction product desorption are significantly influenced by the flow rate of the carrier gas. This work sheds dynamical insight into the nature of MoS2 monolayer synthesis and establishes a universal way to tackle challenges in preparing high-quality crystal substrates, enabling their generalization to other 2D materials

Dynamic nanoscale imaging of enriched CO adlayer on Pt(111) confined under h-BN monolayer in ambient pressure atmospheres

Fundamental understanding of chemistry confined to nanospace remains a challenge since molecules encapsulated in confined microenvironments are difficult to be characterized. Here, we show that CO adsorption on Pt(111) confined under monolayer hexagonal boron nitride (h-BN) can be dynamically imaged using near ambient pressure scanning tunneling microscope (NAP-STM) and thanks to tunneling transparency of the top h-BN layer. The observed CO superstructures on Pt(111) in different CO atmospheres allow to derive surface coverages of CO adlayers, which are higher in the confined nanospace between h-BN and Pt(111) than those on the open Pt surface under the same conditions. Dynamic NAP-STM imaging data together with theoretical calculations confirm confinement-induced molecule enrichment effect within the 2D nanospace, which reveals new chemistry aroused by the confined nanoreactor

Silica accelerates the selective hydrogenation of CO2 to methanol on cobalt catalysts.

The reaction pathways on supported catalysts can be tuned by optimizing the catalyst structures, which helps the development of efficient catalysts. Such design is particularly desired for CO2 hydrogenation, which is characterized by complex pathways and multiple products. Here,&nbsp;we report an investigation of supported cobalt, which is known for its&nbsp;hydrocarbon production and&nbsp;ability to turn into a selective catalyst for methanol synthesis in CO2 hydrogenation which exhibits good activity and stability. The crucial technique is to use the silica, acting as a support and ligand, to modify the cobalt species via Co‒O‒SiOn linkages, which favor the reactivity of spectroscopically identified *CH3O intermediates, that more readily&nbsp;undergo hydrogenation to methanol than the C‒O dissociation associated with&nbsp;hydrocarbon&nbsp;formation. Cobalt catalysts in this class offer appealing opportunities for optimizing selectivity in CO2 hydrogenation and producing high-grade methanol. By identifying&nbsp;this function of silica, we&nbsp;provide support for rationally controlling these reaction pathways

Author Correction: Silica accelerates the selective hydrogenation of CO2 to methanol on cobalt catalysts

An amendment to this paper has been published and can be accessed via a link at the top of the paper

Surface and Subsurface Structures of the Pt-Fe Surface Alloy on Pt(111)

Pt-Fe bimetallic alloys are important model catalysts for a number of catalytic reactions. Combining scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS), we have studied the structures of Pt-Fe surface alloys prepared on Pt(111) under a variety of conditions. Although the surface and subsurface structures of the Pt-Fe surface alloy could be varied with the deposition amount of Fe atoms and the annealing temperature, a characteristic alloy surface with a bright striped pattern could be identified, which consists of a Pt-dominant surface layer with a small percentage of Fe atoms in the form of isolated atoms or clusters in the surface lattice and a subsurface layer with an ordered Pt3Fe alloy structure. The bright stripes observed in STM were surface dislocations caused by stress relaxation owing to the lattice mismatch between the surface and subsurface layers. This characteristic alloy surface could be prepared on Pt(111) by depositing sub-monolayer Fe at similar to 460 K to facilitate Fe diffusion in the near surface region, or annealing multilayer Fe at similar to 700 K, to enhance bulk diffusion of Fe atoms. The synthesis of this Pt-Fe alloy surface with well-defined structures could allow for further model catalytic studies

Two-Dimensional Chirality Transfer via On-Surface Reaction

Two-dimensional chirality transfer from self-assembled (SA) molecules to covalently bonded products was achieved via on-surface synthesis on Au(111) substrates by choosing 1,4-dibromo-2,5-didodecylbenzene (12DB) and 1,4-dibromo-2,5-ditridecylbenzene (13DB) as designed precursors. Scanning tunneling microscopy investigations reveal that their aryl–aryl coupling reaction occurs by connecting the nearest neighboring precursors and thus preserving the SA lamellar structure. The SA structures of 12(13)­DB precursors determine the final structures of produced oligo-<i>p</i>-phenylenes (OPP) on the surface. Pure homochiral domains (12DB) give rise to homochiral domains of OPP, whereas lamellae containing mixed chiral geometry of the precursor (13DB) results in the formation of racemic lamellae of OPP

CO and H-2 Activation over g-ZnO Layers and w-ZnO(0001)

Graphene-like ZnO (g-ZnO) nanostructures (NSs) and thin films were prepared on Au(111), and their reactivities toward CO and H-2 were compared with that of wurtzite ZnO (w-ZnO) (0001) single crystals. The interaction and reaction between CO/H-2 and the different types of ZnO surfaces were studied using near-ambient-pressure scanning tunneling microscopy (NAP-STM), X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) calculations. The reactivity of the w-ZnO(0001) surface toward CO and H-2 was found to be more prominent than those on the surfaces of g-ZnO/Au(111). CO oxidation took place primarily at the edge sites of w-ZnO(0001) and the interface between g-ZnO NSs and Au(111), while g-ZnO thin films on Au(111) appeared to be inert below 600 K. Similarly, the w-ZnO(0001) surface could dissociate H-2 at 300 K, accompanied by a substantial surface reconstruction, while g-ZnO on Au(111) appeared inert for H-2 activation at 300 K. DFT calculations showed that the reactivities of ZnO surfaces toward CO could be related to the formation energy of oxygen vacancy (E-Ovf), which could be related to the charge transfer to lattice oxygen atoms or surface polarity

Near-field nano-spectroscopy of strong mode coupling in phonon-polaritonic crystals

Strongly coupled phonon polaritons in patterned polar dielectric nano-resonators give rise to the formation of hybridized energy states with intriguing properties. However, direct observation of mode coupling in these periodic nanostructures is still challenging for momentum-matching-required far-field spectroscopies. Here, we explore the near-field response of strong coupling between propagating and localized polariton modes sustained in SiC phonon polaritonic crystals (PhPCs) to reveal the evolution of Rabi splittings with the change of lattice constant in the near-field perspective. The near-field nano-spectra of PhPCs show distinct Rabi splitting near the forbidden bands of ∼16 cm−1 in the band structures. In particular, an exotic three-polariton-coupling effect is observed with three splitting peaks in the nano-spectra induced by the interaction between local monopolar modes in nano-pillars and zone-folded phonon polaritons. Furthermore, sharp dips indicating weak near-field scatterings appear in nano-spectra at the intrinsic frequencies of the monopolar modes with strong local-field enhancement, which are estimated to be bright scattering peaks intuitively. These results would inspire the dispersion engineering and characterization of coupled phononic nano-resonators for diverse nanophotonic applications