Precision Chemistry最新文献

The electrochemical properties of 2D materials, particularly transition metal dichalcogenides (TMDs), hinge on their structural and chemical characteristics. To be practically viable, achieving large-scale, high-yield production is crucial, ensuring both quality and electrochemical suitability for applications in energy storage, electrocatalysis, and potential-based ionic sieving membranes. A prerequisite for success is a deep understanding of the synthesis process, forming a critical link between materials synthesis and electrochemical performance. This review extensively examines the liquid-phase exfoliation technique, providing insights into potential advancements and strategies to optimize the TMDs nanosheet yield while preserving their electrochemical attributes. The primary goal is to compile techniques for enhancing TMDs nanosheet yield through direct liquid-phase exfoliation, considering parameters like solvents, surfactants, centrifugation, and sonication dynamics. Beyond addressing the exfoliation yield, the review emphasizes the potential impact of these parameters on the structural and chemical properties of TMD nanosheets, highlighting their pivotal role in electrochemical applications. Acknowledging evolving research methodologies, the review explores integrating machine learning and data science as tools for understanding relationships and key characteristics. Envisioned to advance 2D material research, including the optimization of graphene, MXenes, and TMDs synthesis for electrochemical applications, this compilation charts a course toward data-driven techniques. By bridging experimental and machine learning approaches, it promises to reshape the landscape of knowledge in electrochemistry, offering a transformative resource for the academic community.

Surface modification of metallic nanocatalysts with organic ligands has emerged as an effective strategy to enhance catalytic selectivity, although often at the expense of catalytic activity. In this study, we demonstrate a compelling approach by surface modifying Pd₄S nanocrystals with PPh₃ ligands, resulting in a catalyst with excellent catalytic activity and durable selectivity for the semi-hydrogenation of terminal alkynes. Experimental and theoretical investigations reveal that the presence of S sites on the Pd surface directs PPh₃ ligands to preferentially form covalent bonds with S, creating distinctive surface S═PPh₃ motifs. This configuration induces a partial positive charge on Pd, facilitating hydrogen transfer and thus promoting catalytic activity. Furthermore, the covalent bond between the ligand and catalyst surface forms a robust network, ensuring ligand stability and increasing the hydrogenation energy barrier of olefins. Consequently, the Pd₄S@PPh₃ catalyst exhibits an improved catalytic selectivity with durability in terminal alkyne semi-hydrogenation. This study introduces an effective strategy for designing selective hydrogenation catalysts with an enhanced performance.

Propane dehydrogenation (PDH), an atom-economic reaction to produce high-value-added propylene and hydrogen with high efficiency, has recently attracted extensive attention. The severe deactivation of Pt-based catalysts through sintering and coking remains a major challenge in this high-temperature reaction. The introduction of Sn as a promoter has been widely applied to improve the stability and selectivity of the catalysts. However, the selectivity and stability of PtSn catalysts have been found to vary considerably with synthesis methods, and the role of Sn is still far from fully understanding. To gain in-depth insights into this issue, we synthesized a series of PtSn/SiO₂ and SnPt/SiO₂ catalysts by varying the deposition sequence and Pt:Sn ratios using atomic layer deposition with precise control. We found that PtSn/SiO₂ catalysts fabricated by the deposition of SnO_x first and then Pt, exhibited much better propylene selectivity and stability than the SnPt/SiO₂ catalysts synthesized the other way around. We demonstrate that the presence of Sn species at the Pt-SiO₂ interface is of essential importance for not only the stabilization of PtSn clusters against sintering under reaction conditions but also the promotion of charge transfers to Pt for high selectivity. Besides the above, the precise regulation of the Sn content is also pivotal for high performance, and the excess amount of Sn might generate additional acidic sites, which could decrease the propylene selectivity and lead to heavy coke formation. These findings provide deep insight into the design of highly selective and stable PDH catalysts.

A class of side-chain type ferrocene macrocycles with a radially conjugated system is introduced in this study. The stereo configurations of these ferrocene rings were determined through single-crystal X-ray diffraction analysis. Notably, in the solid state, the ferrocene rings exhibit a distinctive herringbone stacking pattern imposed by a ferrocene-to-ring host–guest interaction. Through UV–vis absorption spectroscopy, electrochemical measurements, and theoretical calculations, valuable insights into the electronic properties of these rings were obtained. In addition, the single crystal of macrocycle A₂B demonstrates a second-order nonlinear optical response. As a class of organometallic nanorings, this work holds great potential for further exploration in the fields of organometallic chemistry, molecular electronics, and host–guest chemistry.

The past few years have witnessed prominent progress in two-dimensional (2D) van der Waals heterostructures. Vertically assembled in an artificial manner, these atomically thin layers possess distinctive electronic, magnetic, and other properties, which have provided a versatile platform for both fundamental exploration and practical applications in condensed matter physics and materials science. Within various potential combinations, a particular set of van der Waals superconductor (SC) heterostructures, which is realized by stacking fabrication based on two-dimensional SCs, is currently attracting intense attention. For example, the Josephson junction, a specific structure in which a nonsuperconducting barrier is inserted between two proximity-coupled SCs, shows phenomena and outstanding properties with atomic-scale thickness. In this Perspective, we first review this emerging research area of van der Waals SC heterostructures, especially progress on the 2D van der Waals Josephson junctions, from the aspects of preparation, performance, and application, and also propose our vision for the future direction and potential innovation opportunities.

A hydrogen storage system was developed via heterogeneous catalysis, employing the dehydrogenative coupling of methanol and N,N′-dimethylethylenediamine to efficiently produce high-purity H₂. In this process, the Cu/ZnO/Al₂O₃ catalyst displayed superior activity in hydrogen production, with Cu⁺ identified as the major active site through comprehensive characterization.

Supported metal clusters with the integrated advantages of single-atom catalysts and conventional nanoparticles held great promise in the electrocatalytic carbon dioxide reduction (ECO₂R) operated at low overpotential and high current density. However, its precise synthesis and the understanding of synergistically catalytic effects remain challenging. Herein, we report a facile method to synthesize the bimetallic Cu and Ni clusters anchored on porous carbon (Cu/Ni–NC) and achieve an enhanced ECO₂R. The aberration-corrected high-angle annular dark-field scanning transmission electron microscopy and synchrotron X-ray absorption spectroscopy were employed to verify the metal dispersion and the coordination of Cu/Ni clusters on NC. As a result of this route, the target Cu/Ni–NC exhibits excellent electrocatalytic performance including a stable 30 h electrolysis at 200 mA cm^–2 with carbon monoxide Faradaic efficiency of ∼95.1% using a membrane electrode assembly electrolysis cell. Combined with the in situ analysis of the surface-enhanced Fourier transform infrared spectroelectrochemistry, we propose that the synergistic effects between Ni and Cu can effectively promote the H₂O dissociation, thereby accelerate the hydrogenation of CO₂ to *COOH and the overall reaction process.

Copper (Cu) is considered to be the most effective catalyst for electrochemical conversion of carbon dioxide (CO₂) into value-added hydrocarbons, but its stability still faces considerable challenge. Here, we report the poisoning effect of carbon deposition during CO₂ reduction on the active sites of Cu electrode─a critical deactivation factor that is often overlooked. We find that, *C, an intermediate toward methane formation, could desorb on the electrode surface to form carbon species. We reveal a strong correlation between the formation of methane and the carbon deposition, and the reaction conditions favoring methane production result in more carbon deposition. The deposited carbon blocks the active sites and consequently causes rapid deterioration of the catalytic performance. We further demonstrate that the carbon deposition can be mitigated by increasing the roughness of the electrode and increasing the pH of the electrolyte. This work offers a new guidance for designing more stable catalysts for CO₂ reduction.

Metal–nitrogen double bonds have been commonly reported for conventional metal complexes, but the coexistence of both transition metal–nitrogen and lanthanide–nitrogen double bonds bridged by nitrogen within one compound has never been reported. Herein, by encapsulating a ternary transition metal-lanthanide heteronuclear dimetallic nitride into a C₈₄ fullerene cage, transition metal–nitrogen and lanthanide-nitrogen double bonds are costabilized simultaneously within the as-formed clusterfullerene TiCeN@C₁(12)-C₈₄, which is a representative heteronuclear dimetallic nitride clusterfullerene. Its molecular structure was unambiguously determined by single-crystal X-ray diffraction, revealing a slightly bent μ₂-bridged nitride cluster with short Ti–N (1.761 Å) and Ce–N (2.109 Å) bond lengths, which are comparable to the corresponding Ti═N and Ce═N double bonds of reported metal complexes and consistent with the theoretically predicted values, confirming their coexistence within TiCeN@C₁(12)-C₈₄. Density functional theory (DFT) calculations unveil three-center two-electron (3c-2e) bonds delocalized over the entire TiCeN cluster, which are responsible for costabilization of Ti═N and Ce═N double bonds. An electronic configuration of Ti⁴⁺Ce³⁺N^3–@C₈₄^4– is proposed featuring an intramolecular four-electron transfer, drastically different from the analogous actinide dimetallic nitride clusterfullerene (U₂)⁹⁺N^3–@C₈₀^6– and trimetallic nitride clusterfullerene (Sc₂)⁶⁺Ti³⁺N^3–@C₈₀^6–, indicating the peculiarity of 4-fold negatively charged fullerene cage in stabilizing the heteronuclear dimetallic nitride cluster.