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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, we report an investigation of supported cobalt, which is known for its hydrocarbon production and 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 undergo hydrogenation to methanol than the C‒O dissociation associated with hydrocarbon formation. Cobalt catalysts in this class offer appealing opportunities for optimizing selectivity in CO2 hydrogenation and producing high-grade methanol. By identifying this function of silica, we provide support for rationally controlling these reaction pathways.

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. [ABSTRACT FROM AUTHOR]

Surface nanostructures serve as an essential role in determining intrinsic physical features and device performance in solid materials. Here, this work systematically investigates the surface dynamical evolution at the nanoscale on Au(111) induced by a "tip-to-surface" external electric field through a scanning tunneling microscope (STM). The Au(111) steps exhibit a "compact to fractal" reconstruction under a relatively high electric field, in which the transition is strengthened with increasing the applied electric field. Inversely, a "fractal to compact" morphological transition enables to be self-triggered at Au(111) surface steps upon a normal STM imaging electric field (very low). These two reversible structural changes are attributed to the diffusion-limited aggregation mechanism where the diffusion barriers were quantified as 0.64–0.75 eV varied with the regularity in step edges. In addition, we further simulate a "terrace-edge-kink" model to trace the effect of atomic coordination on structural transition, determining the surface step edge stability. This study presents insight into morphological and structural transformation at surface steps induced by variant external electric fields, establishing a deep understanding in the nature of surface evolution dynamics. [ABSTRACT FROM AUTHOR]

Actual chemical states of single-atom metal on reducible supports remain a fiercely debated topic under reactive environments. Herein, we demonstrate that the single-atom Pt on Co3O4 surface undergoes an in-situ reconstruction to form isolated Pt-Co bimetallic sites via reducing coordination number of Pt—O in the presence of hydrogen from both simulations and in-situ X-ray photoelectron spectroscopy. The modified chemical states of Pt greatly promoted H2 activation, thus delivering a significantly high turnover frequency of 7,448 h−1 (19.5 times over Pt nanoparticles on Co3O4) for hydrogenation of cinnamaldehyde. The satisfactory selectivity of 95.2% towards cinnamyl alcohol was ascribed to a tilted adsorption configuration of reactant on the catalyst surface via aldehyde group. We anticipate that the recognitions on in-situ reconstruction of single-atom catalysts (SACs) under the reducing conditions benefit the design of highly-performed hydrogenation catalysts. [ABSTRACT FROM AUTHOR]

Long‐term stability has become the major obstacle for the successful large‐scale application of perovskites devices. Owing to the ionic nature of metal‐halide perovskites, the interfacial ion diffusion can induce irreversible degradation under operational conditions, which presents a great challenge to realize stable perovskite solar modules. Here, a diphenylphosphine oxide compound, ethane‐1,2‐diylbis(diphenylphosphine oxide) (DPPO) is introduced to coordinate with lead iodide and form a cross‐linked 1D Pb3I6‐DPPO (1D‐PbI2) complex. These judiciously designed cross‐linked nonionic low‐dimensional lead halide/organic adducts can passivate the defects of perovskite while acting as a robust ion diffusion barrier, thus significantly improving the electronic quality and intrinsic stability of perovskite films. As a result, high‐performance inverted (p‐i‐n) solar modules with a champion efficiency approaching 19% (a certified stabilized efficiency of 17.8%) for active device areas above 17 cm2 without the use of antisolvents, accompanied by outstanding operational stability under heat stress and continuous illumination are achieved. [ABSTRACT FROM AUTHOR]